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ID Date Author Type Category Subject
12856   Tue Feb 28 18:25:22 2017 ranaUpdatePEMETMX damping recovered

Huh? So should we ask them to put the container back? Or do you have some other theory about ETMX tripping that is not garbage related?

 Quote: ETMX sus damping recovered. Note: The giant metal garbage container was moved from the south west corner of CES months ago.

12884   Mon Mar 13 16:47:41 2017 SteveUpdatePEMY-arm air conditon belts replaced

The east end AC unit is arching over and running rough at CES. Called for mechanic.......

Both belts were replaced and the unit is running happily.

12895   Mon Mar 20 17:12:08 2017 steveUpdatePEMparticle counter inside of PSL enclousure

The logging script is multiplying by 100 instead of 10 !

 Quote: The MET#1 particle counter was moved from CES wall at ITMX to PSL enclousure south west corner at 11am. The HEPA filter speed at the Variac was turned down to 20V from 40 This counter pumps air for 1 minute in every 20 minutes. Soft foam in bags used to minimize this shaking as it is clamped.

Attachment 1: enclousure_partical_count.png
12908   Mon Mar 27 15:36:27 2017 SteveUpdatePEMparticle counter inside of PSL enclousure

Quote:

The logging script is multiplying by 100 instead of 10 !

 Quote: The MET#1 particle counter was moved from CES wall at ITMX to PSL enclousure south west corner at 11am. The HEPA filter speed at the Variac was turned down to 20V from 40 This counter pumps air for 1 minute in every 20 minutes. Soft foam in bags used to minimize this shaking as it is clamped.

Some one turned up the PSL HEPA rotation voltage from 20 V to 33 ( 120V Variac ) and  X-arm AC set temp lowered to 68F

Effects at 12" height from optical table :

1.0, 0.5 & 0.3 micron particle count  goes to zero and temperature fluctuaion increased

Rotation speed voltage was set to 30V

Attachment 1: HEPA_flow_effects.png
12909   Mon Mar 27 16:01:55 2017 SteveUpdatePEMX arm AC set to 68F

The X arm air conditioner was not regulating properly. The arm temp was warmer than usual. I requested thermistor calibration.

The mechanic reset the thermostate to 68F last week.  It was 70-71F before.

The ETMX oplev laser now running 4 C lower at 30 C inside the enclousure.

The ETMX optical table top is 5 C cooler  at 21 C

The ETMX concrete wall temp 20 C at 9am with flow bench on.

ETMY conrete wall  temp 23 C at 9am

12930   Thu Apr 6 15:35:44 2017 SteveUpdatePEM envioirmental noise

Building:         Central Engineering Services

Date:             Monday, 04/10/17

Time:             7:00 AM TO 9:00 AM

Contact:          Ben Smith, X-4190 Brad Nielsen, X-8751

Contractors will be removing the large vaporizer located on the South

side of CES. Vehicle access will be restricted due to crane placement

and operation, but there will be a single traffic lane available. This

work may create minor noise and vibrations.

13046   Wed Jun 7 10:07:00 2017 SteveUpdatePEMair condition thermostate

The Y arm ac thermostate was calibrated after cooling water relay replacement by Mike.... yesterday. The set temp is remaind to be 70F

The east end south wall temp is reading 22C

13183   Thu Aug 10 14:13:23 2017 KiraSummaryPEMtemperature sensor

Goal is to build a temperature sensor accurate to 1 mK. Schematic is shown below. This does not take into account the DC gain that occurs.

Parts that would be used for this: LM317 regulator, AD592 temperature transducer, OP amp (low input noise and high impedance), 100K (or maybe 10k) resistor. This is what is currently proposed, but the exact parts we use could be changed to better fit the sensor. The resistor and the OP amp will be decided depending on the output of the AD592.

Once this is built, I would like to create a few copies of it and put them into an insulated container and measure the output from each one. This would allow us to calculate the temperature noise of the circuit, as we can take out the variations due to temperature changes inside the container by comparing the outputs.

I can also model the noise in the circuit to see how much noise there is before building it. There are three terms to the noise that we have, and we need to decide which one dominates at low frequencies.

Our final goal is to create an additional circuit that could cancel out the DC gain. I have attached an additional schematic proposed by Rana that would help with this issue. I will leave this second half for when the first part works.

Attachment 1: IMG_20170810_121637~2.jpg
Attachment 2: IMG_20170810_134422~2.jpg
13184   Thu Aug 10 14:14:17 2017 KiraUpdatePEMpreviously built temp sensor

I decided to see what was inside the sensor that had been previously made. According to elog 1102, the temperature sensor is LM34, the specs of which can be found here:

The wiring of this sensor confused me, as it appears that the +Vs end (white) connects to the input, but both the ground (left) and the Vout (middle) pins are connected to the box itself. I don't see how the signal can be read.

Attachment 1: IMG_20170810_112315.jpg
13188   Thu Aug 10 21:22:06 2017 ranaSummaryPEMtemperature sensor
• Should we use the AD590 or the AD592? They're sort of the same, but have slightly different packages and specs.
• Given the sensitivity of the AD590 to power supply drift, I would recommend using a precision voltage reference like the AD581 or AD587. Take a look at the datasheets and order a few different varieties so we can see what works best for us. I believe that the voltage regulators have too much drift to use for precision temperature control.
• The AD590 datasheet has a few example circuits showing how we can subtract off the offset which comes the 1 uA/K coefficient of the AD590 (i.e. we would have 295 uA at room temperature, trying to stabilize to +/- 0.1 K)
• For the first prototypes its fine to use some solderable protoboard assembly, but we will eventually have to figure out how to package this thing and interface it with our Acromag slow controls system.

also, I've attached some temperature noise spectra from the LISA group at the AEI in Hannover. It will be interesting to see if we get the same results.

Attachment 1: tempsensnoise2.pdf
Attachment 2: tempnoise_final.pdf
13190   Fri Aug 11 10:27:49 2017 KiraUpdatePEMtemperature sensor

Since there seems to be little difference between AD590 and AD592, I guess we could just go with the AD590. The temperature noise spectrum in the first graph are for the AD590, so if we want to reproduce those results, we should use AD590.

For the AD581/AD587, we could go with a few varieties that have the least output voltage drift, although I am not sure what precision we will need. So maybe we could try AD587U and AD581L. We could also try AD587K and AD581K and see if those work as well.

We will also need to calibrate the sensor, as it takes an input of 5V, but the AD581/AD587 provides 10V, which will give about a 1 degree error according to the datasheet. It does state that this is only a calibration error, so it shouldn't be too much of an issue.

I will figure out the packaging once I construct the sensor and verify that it works. Maybe we could use a box similar to the existing sensor, but it depends on the size of the finished circuit.

13191   Fri Aug 11 10:48:39 2017 KiraUpdatePEMtemperature sensor

Quick update: we actually have AD587KRZ and AD592, so we could start by using that and seeing how it works.

13193   Fri Aug 11 11:56:02 2017 ranaUpdatePEMtemperature sensor

Might as well order several of a few different varieties today. Its good to have some extra in stock; we don't always want to have to wait days for parts to show up. If you give Steve a list of parts to buy he can order them today or Monday.

There should also be some precision 5V sources (e.g. AD586) that you can try.

13194   Fri Aug 11 12:27:25 2017 KiraUpdatePEMtemperature sensor

Used AD592CNZ and AD586 (5V output) to create a circuit that works and is responsive to temperature changes. At room temp, using ~1K resistor, it showed ~0.3V across it, as expected. The voltage went up when we heated it with a heating gun. Next step will be to add in an OP amp and design some experiments to check to see how accurate it is. Thanks to Gautam for helping me with it!

I have attached the working circuit and a close up of the connections.

Attachment 1: IMG_20170811_121608.jpg
Attachment 2: IMG_20170811_121619.jpg
13202   Mon Aug 14 09:49:18 2017 KiraUpdatePEMtemperature sensor

Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating.

I've attached a few pictures showing the circuit.

Attachment 1: IMG_20170814_092452.jpg
Attachment 2: IMG_20170814_092513.jpg
13203   Mon Aug 14 12:52:33 2017 KiraUpdatePEMtemperature sensor

I didn't realize that the LT1012 needed an additional input to function. I added in +15V and -15V to pins 7 and 4, respectively and placed a 10k resistor and the numbers make more sense now. The voltage showed a negative value, but it became more negative as I heated it up (it's negative due to how a transimpedance amplifier works).

I have attached the new setup and the value it shows (~-3V). It became more negative by about 0.4V, which translates to about a 40K increase in temperature, which makes sense.

In addition, I have attached an updated sketch of the circuit. I will need to do more testing to determine how accurate this is. The next step would be to calculate how much noise there is currently and figure out how to remove this circuit from the breadboard and use a PCB or something like that for final testing in an insulated container.

The reason I chose AD743 initially for the OP amp is because at low frequencies (which is what we are working with), a FET amp such as AD743 will have a low current noise at high impedance, which is what we have in this case. While a FET amp has high voltage noise compared to other OP amps, the current noise becomes more important at high impedance, so it will work better. According to Zach's graphs, the AD743 is best at high impedances, followed by LT1012.

 Quote: Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating. I've attached a few pictures showing the circuit.

Attachment 1: IMG_20170814_121131.jpg
Attachment 2: IMG_20170814_121139.jpg
Attachment 3: IMG_20170814_121758~2.jpg
13209   Tue Aug 15 11:50:21 2017 KiraSummaryPEMtemp sensor packaging/mount

For the final packaging/mounting of the sensor to the seismometer, I have thought of two options.

1. Attach circuit to a PCB board and place it inside the can, while leaving the AD590 open to the air inside the can.

• This makes sure that the sensor gets a direct measurement of the temperature of the air in the can, as it is exposed to the air.
• But, it takes a limited area of measurement, so it could be the case that the area we place it in happens to be a hot or cold pocket, and the measurement would be inaccurate.
• This can be solved by placing multiple copies of the circuit in various places of the can and averaging the values.

2. Attach the AD590 to a copper plate with thermal paste and put it into a pomona box.

• This solves the problem of having a limited sample area the first option had, as the copper plate should have a uniform temp distribution, thus we are sampling the temp of that whole area.
• Need to make sure that the response time to the temperature variations of copper is less than the frequency that we are measuring.
• This can be calculated using equations for heat transfer (listed below).

If anyone has input on which method is preferred or any additional options that we may have, I would appreciate it.

Heat transfer:

q = k A dT / s

• k = thermal conductivity
• A = area
• s = thickness

For copper, k = 401 W/mK, x = 1.27 mm, A = 2.66x10^-3 m^2 (for the particular copper plate I measured), dT = 1K (assume). Thus the heat transfer will be 839 J/s.

I'm not completely sure what to do with this yet, but it could help us decide whether the copper plate option will be useful for us.

13210   Tue Aug 15 13:32:38 2017 KiraUpdatePEMtemperature sensor

Tested to make sure that even when only the AD586 was heated that there was no change in the reading. I did so by placing the AD586 away from the rest of the circuit and blowing hot air only on it. There was, in fact, no change.

Quote:

I didn't realize that the LT1012 needed an additional input to function. I added in +15V and -15V to pins 7 and 4, respectively and placed a 10k resistor and the numbers make more sense now. The voltage showed a negative value, but it became more negative as I heated it up (it's negative due to how a transimpedance amplifier works).

I have attached the new setup and the value it shows (~-3V). It became more negative by about 0.4V, which translates to about a 40K increase in temperature, which makes sense.

In addition, I have attached an updated sketch of the circuit. I will need to do more testing to determine how accurate this is. The next step would be to calculate how much noise there is currently and figure out how to remove this circuit from the breadboard and use a PCB or something like that for final testing in an insulated container.

The reason I chose AD743 initially for the OP amp is because at low frequencies (which is what we are working with), a FET amp such as AD743 will have a low current noise at high impedance, which is what we have in this case. While a FET amp has high voltage noise compared to other OP amps, the current noise becomes more important at high impedance, so it will work better. According to Zach's graphs, the AD743 is best at high impedances, followed by LT1012.

 Quote: Decided to try adding in an OP amp just to see if it would work. Added LT1012 and a 100k resistor to the circuit (I originally wanted to do AD743 as it seems to be the best choice according to Zach's elog here, but it said that they are very precious so I went with LT1012 for testing purposes). When heating it with a heating gun, the output voltage went down by a few 0.01V. The maximum voltage was 0.686V. Similar thing happened when I switched to a 10k resistor, where the maximum was 0.705V and it also went down by a few 0.01V upon heating. I've attached a few pictures showing the circuit.

13214   Wed Aug 16 16:05:53 2017 KiraUpdatePEMtemp sensor PCB

Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well.

Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is.

Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170816_154514.jpg
Attachment 2: IMG_20170816_154541.jpg
13224   Thu Aug 17 10:41:58 2017 KiraUpdatePEMtemp sensor PCB

Got it to work. One of the connections was faulty. I decided to check the temperature measured against a thermometer. The sensor showed 26.1 C, but the thermometer showed 25.8 C after I let them both cool down after heating them up. The temperature of the thermometer was dropping at the time of measurement, but the temperature of the sensor was not. This is still a rough version of the final sensor, so I'm not sure what exactly causes this discrepancy.

 Quote: Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well. Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is. Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170817_095917.jpg
13232   Mon Aug 21 13:07:08 2017 KiraUpdatePEMtemp sensor PCB

On Friday, I cleaned up the circuit so that there are only three connections needed (+15V, -15V, GND) and a BNC connector for reading the output. Today, I added in bypass capacitors. The small yellow ones are 0.1 microF ceramic, and the large ones are 100 microF electrolytic. They are used to stabilize the +15V and -15V inputs to the OP amp and minimize fluctuations, since it doesn't have a regulator for stability. I have also attached the circuit diagram for the OP amp only, where 1 are the electrolytic and 2 are the ceramic. The temperature is still about 2 degrees off, but if that difference is constant for all temperatures in our range we can just calibrate it later.

Here is a helpful link on bypass capacitors (thanks to Kevin for sending it to me).

As a note, the electrolytic capacitors do have a polarity, so it is important to place them correctly (the negative side is towards the lower voltage potential, and not always towards ground).

Quote:

Got it to work. One of the connections was faulty. I decided to check the temperature measured against a thermometer. The sensor showed 26.1 C, but the thermometer showed 25.8 C after I let them both cool down after heating them up. The temperature of the thermometer was dropping at the time of measurement, but the temperature of the sensor was not. This is still a rough version of the final sensor, so I'm not sure what exactly causes this discrepancy.

 Quote: Tried taking the circuit from the breadboard to the PCB. I attached all the components to adapters that would allow them to be connected to the PCB. From the first picture, the first component is AD586, the second is AD590, and the third is LT1012, along with a resistor across it. I then soldered the connections between the components, as can be seen in the second picture. When I tested out this version of the circuit by hooking it up to the DC source, I got a reading of ~-15V. I will have to check all the connections to make sure there is contact where there should be one, and no contact where there shouldn't be. I had issues attaching the tiny AD590 and LT1012 to its adaptor, so the issue may lie there as well. I'll also check that each component is in working order as well. Once I figure out where my error is, my plan is to build two more of these and place a metal object such that it contacts only the surface of the AD590s. This would allow me to compare the three values to the actual temperature of the metal, which would then tell me how accurate this setup is. Note on the resistor: I measured all the resistors and chose three that had exactly 10.00k Ohm. The voltage detected is dependent on the resistor, so if we are to take three identical copies, I ensured that there would be no error due to the resistors being a little different.

Attachment 1: IMG_20170821_124121.jpg
Attachment 2: IMG_20170821_124429~2.jpg
Attachment 3: IMG_20170821_124108.jpg
13269   Tue Aug 29 15:41:17 2017 KiraSummaryPEMheater circuit

I worked with Kevin and Gautam to create a heater circuit. The first attachment is Kevin's schematic of the circuit. The OP amp connects to the gate of the power MOSFET, and the power supply connects to the drain, while the source goes into the heater. We set the power supply voltage to 22V and varied the voltage of the input to the OP amp. At 6V to the OP amp, we got a current of 0.35A flowing through the heater and resistor. This was the peak current we got due to the OP amp being saturated (an increase in either of the power supplies did not change the current), but when we increased the voltage of the supply rails of the OP amp from 15V to 20V, we got a current of 0.5A. We would want a higher current than this, so we will need to get a different OP amp with a higher max voltage rating, and a resistor that can take more power than this one (it currently takes 5W of power, and is the best one we could find).

Kevin and I created a simulation of this circuit using CircuitLab to understand why the current was so low (second attachment). The horizontal axis is the voltage we supply to the OP amp. The blue line shows the voltage at the point between the output of the OP amp and the gate of the MOSFET. The orange line is the voltage at the point between the source of the MOSFET and the heater. The brown line is the voltage at the point between the heater and resistor. Thus, we can see that saturation occurs at about 2.1V. At that point, the gate-source voltage is the difference between the blue curve and the orange curve, which is about 4V, which is what we measured. Likewise, the voltage across the heater is the difference between the orange curve and the brown curve, which comes out to around 8V, which is also what we measured. Lastly, the voltage across the resistor is the brown curve, which is about 2V, which matches our observations. The circuit works as it should, but saturates too soon to get a high enough current out of it.

Gautam noted that it is important to measure the current correctly. We can't just use an ammeter and place it across the resistor or heater, because the internal resistance of the ammeter (~0.5 ohm) is comparable to the resistance we want to measure, so the current gets split between the circuit and the ammeter and we get an equivalent resistance of 1/R = 1/R0 + 1/Ra, where R0 is the resistance of the part we want to measure the current across, and Ra is the ammeter resistance. Thus, the new resistance will be lower and the ammeter will show a higher current value than what is actually there. So to accurately measure the current, we must place the ammeter in series with the part we want to measure. We initially got a 1A reading on the heater, which was not correct, and our setup did not heat up at all basically. When we placed the ammeter in series with the heater, we got only 0.35A.

The last two images are the setup for testing of the heater. We wrapped it around an aluminum piece and covered it with a few layers of insulating material. We can stick a thermometer in between the insulation and heater to see the temperature change. In later tests, we may insulate the whole piece so that less heat gets dissipated. In addition, we used a heat sink and thermal paste to secure the MOSFET to it, as it got very hot.

Our next steps will be to get a resistor and an OP amp that are better suited for our purposes. We will also run simulations with components that we choose to make sure that it can provide the desired current of 1A (the maximum output of the power supply is 24V, and the heater is 24 ohm, so max current is 1A). Kevin is working on that now.

Attachment 1: heater_circuit.pdf
Attachment 2: simulation.png
Attachment 3: heater_setup.jpg
Attachment 4: IMG_20170829_131126.jpg
13272   Wed Aug 30 06:45:32 2017 KevinSummaryPEMNew Heater Circuit

I changed the heater circuit described in this elog to a current sink. The new and old circuits are shown in the attachment. The heater is $R_h$ and is currently 24Ω; the sense resistor $R$ is currently 6Ω. The op-amp is still an OP27 and the MOSFET is still an IRF630.

The current through the old circuit was saturating because the gate voltage on the MOSFET was saturating at the op-amp supply rails. This is because the source voltage is relatively high: $V_S = I(R + R_h)$.

In the new circuit the source voltage is lower and the op-amp can thus drive a large enough $V_{GS}$ to draw more current (until the power supply saturates at 25V/30Ω = 0.8A in this case). The source and DAC voltages are equal in this case$V_{\mathrm{DAC}} = V_S$ and so the current is $I = V_{\mathrm{DAC}}/R$. Since this is the same current through the heater, the drain voltage is $V_D = V_{cc} - IR_h$. I observed this behavior in this circuit until the power supply saturated at 0.8A. Note that when this happens $V_D = V_S$ and the gate voltage saturates at the supply rails in an attempt to supply the necessary current.

Attachment 1: circuit.pdf
13285   Fri Sep 1 15:46:12 2017 KiraUpdatePEMtemp sensor update

I took off the AD590 and attached it to two long wires leading out from the board. This will allow us to attach the sensor to a metal block and not have to stick the whole board to it. I have also completed three identical copies of this and it's pretty much ready to be tested. According to Craig and Andrew's elog here, the sensor is very noisy and they added in a low pass filter to fix that, so that's something to consider for the final version of the circuit. I'll test what I have so far and see how that goes. We still need to figure out how to get readings from the sensors.

To attach the sensor to the metal block, I'll use some thermal paste and fasteners. I'll also put a thermometer on the block to record the actual temperature. I'll then wrap it in some insulation we have in the lab and have only some wires leading out of it to make measurements. I'll leave this setup overnight and record the outputs for about a full day. The fluctuations between the sensors will then indicate the noise of each individual sensor.

Attachment 1: IMG_20170901_144729.jpg
13292   Tue Sep 5 09:47:34 2017 KiraSummaryPEMheater circuit calculations

I decided to calculate the fluctuation in power that we will have in the heater circuit. The resistors we ordered have 50 ppm/C and it would be useful to know what kind of fluctuation we would expect. For this, I assumed that the heater itself is an ideal resistor that has no temperature variation. The circuit diagram is found in Kevin's elog here. At saturation, the total resistance (we will have a $1\Omega$ resistor instead of $6\Omega$ for our new design) will be $R_{tot}=R+R_{h}=1\Omega +24\Omega =25\Omega$. Therefore, with a 24V input, the saturation current should be $I=\frac{V_{in}}{R_{tot}}=\frac{24V}{25\Omega}=0.96A$.  Therefore, the power in the heater should be (in the ideal case) $P=I^2R{_{h}}=22.1184W$

Now, in the case where the resistor is not ideal, let's assume the temperature of the resistor changes by 10C (which is about how much we would like to heat the whole thing). Therefore, the resistor will have a new value of $R_{new}=R+50ppm/C\times 10C\times 10^{-6}=1.0005\Omega$. The new current will then be $I_{new}=\frac{V_{in}}{R_{new}}=0.95998A$ and the new power will be $P_{new}=I_{new}^{2}R_{h}=22.1175W$. So the difference in power going through the heater is about 0.00088W.

We can use this power difference to calculate how much the temperature of the metal can we wish to heat up will change. $\Delta T=\Delta P\times (1/\kappa) /x$ where $\kappa$ is the thermal conductivity and x is the thickness of the material. For our seismometer, I calculated it to be 0.012K.

13295   Tue Sep 5 17:18:17 2017 KiraUpdatePEMtemp sensor update

Today, I stuck on the sensors to a metal block using a flag, rubber bands, and some thermal paste (1st attachment). I then wrapped the whole thing in about 4 layers of insulation and a lot of tape (2nd attachment). The only things leading out of the box were the three connections to the sensors and a thermometer. I then connected the wires to their respective places on the board of the sensor. To get the readings out we would need to use an ADC. Gautam and I checked to make sure the ADC we have inside the lab goes from -10V to 10V so that it would be able to measure the 3V value the sensor typically measures. We then tried to connect all three sensors to a DC source simultaneously, but unfortunately one of them seems to have disconnected somewhere during the process, as it only showed 1.2V instead of 3V. I plan to fix this tomorrow morning so that we can hopefully set this up soon.

 Quote: I took off the AD590 and attached it to two long wires leading out from the board. This will allow us to attach the sensor to a metal block and not have to stick the whole board to it. I have also completed three identical copies of this and it's pretty much ready to be tested. According to Craig and Andrew's elog here, the sensor is very noisy and they added in a low pass filter to fix that, so that's something to consider for the final version of the circuit. I'll test what I have so far and see how that goes. We still need to figure out how to get readings from the sensors. To attach the sensor to the metal block, I'll use some thermal paste and fasteners. I'll also put a thermometer on the block to record the actual temperature. I'll then wrap it in some insulation we have in the lab and have only some wires leading out of it to make measurements. I'll leave this setup overnight and record the outputs for about a full day. The fluctuations between the sensors will then indicate the noise of each individual sensor.

Attachment 1: IMG_20170905_144924.jpg
Attachment 2: IMG_20170905_165042.jpg
13296   Tue Sep 5 17:52:06 2017 KiraUpdatePEMtemp sensor update

to get the sensors to read the same values they have to be in direct thermal contact with the metal block - there can't be any adapter board in-between

for the 2nd attempt, I also recommend encasing it in a metal block rather than just one side. You can drill some 7-10 mm diameter holes in an aluminum or copper block. Then put the sensors in there and plug it up with some thermal paste.

13302   Fri Sep 8 07:54:04 2017 SteveUpdatePEMM8.1 eq

Nothing tripped. No obvious damage.

Attachment 1: M8.1.png
13303   Fri Sep 8 10:22:30 2017 SteveUpdatePEMtemp sensor update

The weight of SS can with copper liner  is 12.2 kg

Is 1 Amp for the heating jacket going to be enough? We should have some headroom.

 Quote: to get the sensors to read the same values they have to be in direct thermal contact with the metal block - there can't be any adapter board in-between for the 2nd attempt, I also recommend encasing it in a metal block rather than just one side. You can drill some 7-10 mm diameter holes in an aluminum or copper block. Then put the sensors in there and plug it up with some thermal paste.

13309   Mon Sep 11 16:46:09 2017 SteveUpdatePEMearthquakes
 Quote: I was trying to get a lossmap measurement over the weekend but had some trouble first with the IMC and then with the PMC. For the IMC: It was a bit too misaligned to catch and maintain lock, but I had a hard time improving the alignment by hand. Fortunately, turning on the WFS quickly once it was locked restored the transmission to nominal levels and made it maintain the lock for longer, but only for several minutes, not enough for a lossmap scan (can take up to an hour). Using the WFS information I manually realigned the IMC, which made locking easier but wouldn't help with staying locked. For the PMC: The PZT feedback signal had railed and the PMC had been unlocked for 8+ hours. The PMC medm screen controls were generally responsive (I could see the modes on the CCDs changing) but I just couldn't get it locked. c1psl was responding to ping but refusing telnet so I keyed the crate, followed by a burt restore and finally it worked. After the PMC came back the IMC has already maintained lock for more than an hour, so I'm now running the first lossmap measurements.

Southern Mexio is still shaking..... so as we

Attachment 1: M5.4eq.png
13311   Tue Sep 12 11:44:16 2017 KiraUpdatePEMtemp sensor update

Got it to work. A cable was broken and the AD586 also broke at the same time so it took a while to find the problem. I had to create a makeshift cable out of three parts so once I replace it for an actual cable, it will be good to go for a test.

Quote:

Today, I stuck on the sensors to a metal block using a flag, rubber bands, and some thermal paste (1st attachment). I then wrapped the whole thing in about 4 layers of insulation and a lot of tape (2nd attachment). The only things leading out of the box were the three connections to the sensors and a thermometer. I then connected the wires to their respective places on the board of the sensor. To get the readings out we would need to use an ADC. Gautam and I checked to make sure the ADC we have inside the lab goes from -10V to 10V so that it would be able to measure the 3V value the sensor typically measures. We then tried to connect all three sensors to a DC source simultaneously, but unfortunately one of them seems to have disconnected somewhere during the process, as it only showed 1.2V instead of 3V. I plan to fix this tomorrow morning so that we can hopefully set this up soon.

 Quote: I took off the AD590 and attached it to two long wires leading out from the board. This will allow us to attach the sensor to a metal block and not have to stick the whole board to it. I have also completed three identical copies of this and it's pretty much ready to be tested. According to Craig and Andrew's elog here, the sensor is very noisy and they added in a low pass filter to fix that, so that's something to consider for the final version of the circuit. I'll test what I have so far and see how that goes. We still need to figure out how to get readings from the sensors. To attach the sensor to the metal block, I'll use some thermal paste and fasteners. I'll also put a thermometer on the block to record the actual temperature. I'll then wrap it in some insulation we have in the lab and have only some wires leading out of it to make measurements. I'll leave this setup overnight and record the outputs for about a full day. The fluctuations between the sensors will then indicate the noise of each individual sensor.

13322   Tue Sep 19 14:00:41 2017 SteveUpdatePEMearthquakes

No sus tripped. Seimometers do not see the 5.3M  ?

 Quote: Southern Mexio is still shaking..... so as we

Attachment 1: 7.1MX5.3J.png
13397   Mon Oct 23 09:17:41 2017 SteveUpdatePEMants alart

Do not leave organic trash or food boxes in the 40m to attrack ants !

Attachment 1: ants.jpg
Attachment 2: ants2.jpg
13402   Fri Oct 27 09:34:20 2017 SteveUpdatePEMearthquakes

Lompoc 4.3M and 3.7M Avalon

Attachment 1: recentEQs.png
13419   Wed Nov 8 16:39:24 2017 KiraUpdatePEMADC noise measurement

Gautam and I measured the noise of the ADC for channels 17, 18, and 19. We plan to use those channels for measuring the noise of the temperature sensors, and we need to figure out whether or not we will need whitening and if so, how much. The figure below shows the actual measurements (red, green and blue lines), and a rough fit. I used Gautam's elog here and used the same function, $\sqrt{a^{2}(\frac{b}{f^{2}})+c^{2}}$ (with units of nV/sqrt(Hz)) to fit our results. I used a = 1, b = 1e6, c = 2000. Since we are interested in measuring at lower frequencies, we must whiten the signal from the temperature sensors enough to have the ADC noise be negligible.

We want to be able to measure to $\inline 1mK/\sqrt{Hz}$ accuracy at 1Hz, which translates to about $\inline 1nA/\sqrt{Hz}$ current from the AD590 (because it gives $\inline 1\mu A/K$). Since we have a 10K resistor and V=IR, the voltage accuracy we want to measure will be $\inline 10^{-5}V/\sqrt{Hz}$. We would need whitening for lower frequencies to see such fluctuations.

To do the measurements, we put a $\inline 50\Omega$ BNC end cap on the channels we wanted to measure, then took measurements from 0-900Hz with a bandwidth of 0.001Hz. This setup is shown in the last two attachments. We used the ADC in 1X7.

Attachment 2: IMG_20171108_162532.jpg
Attachment 3: IMG_20171108_162556.jpg
13424   Fri Nov 10 13:46:26 2017 SteveUpdatePEMM3.1 local earthquake

BOOM SHAKA-LAKA

Attachment 1: 3.1M_local_EQ.png
13427   Tue Nov 14 16:02:43 2017 KiraSummaryPEMseismometer can testing

I made a model for our seismometer can using actual data so that we know approximately what the time constant should be when we test it out. I used the appendix in Megan Kelley's report to make a relation for the temperature in terms of time.

$\frac{dQ}{dt}=mc\frac{dT(t)}{dt}$ so $T(t)=\frac{1}{mc}\int \frac{dQ}{dt}dt=\frac{1}{mc}\int P_{net}dt$ and $P_{net}=P_{in}-P_{out}$

In our case, we will heat the can to a certain temerature and wait for it to cool on its own so $\inline P_{in}=0$

We know that $\inline P_{out}=\frac{kA\Delta T}{d}$ where k is the k-factor of the insulation we are using, A is the area of the surface through which heat is flowing, $\inline \Delta T$ is the change in temperature, d is the thickness of the insulation.

Therefore,

$T(t)=\frac{1}{mc}\int_{0}^{t}\frac{kA}{d}[T_{lab}-T(t')]dt'=\frac{kA}{mcd}(T_{lab}t-\int_{0}^{t}T(t')dt')$

We can take the derivative of this to get

$T'(t)=\frac{kAT_{lab}}{mcd}-\frac{kA}{mcd}T(t)$, or $T'(t)=B-CT(t)$

We can guess the solution to be

$T(t)=C_{1}e^{-t/\tau}+C_{2}$ where tau is the time constant, which we would like to find.

The boundary conditions are $\inline T(0)=40$ and $\inline T(\infty)=T_{lab}=24$. I assumed we would heat up the can to 40 celcius while the room temp is about 24. Plugging this into our equations,

$\inline C_{1}+C_{2}=40, C_{2}=24$, so $\inline C_{1}=16$

We can plug everything back into the derivative T'(t)

$T'(t)=-\frac{16}{\tau}e^{-t/\tau}=B-C[16e^{-t/\tau}+24]$

Equating the exponential terms on both sides, we can solve for tau

$\frac{16}{\tau}e^{-t/\tau}=16Be^{-t/\tau}, \frac{1}{\tau}=B, \tau=\frac{1}{B}=\frac{mcd}{kA}$

Plugging in the values that we have, m = 12.2 kg, c = 500 J/kg*k (stainless steel), d = 0.1 m, k = 0.26 W/(m^2*K), A = 2 m^2, we get that the time constant is 0.326hr. I have attached the plot that I made using these values. I would expect to see something similar to this when I actually do the test.

To set up the experiment, I removed the can (with Steve's help) and will place a few heating pads on the outside and wrap the whole thing in a few layers of insulation to make the total thickness 0.1m. Then, we will attach the heaters to a DC source and heat the can up to 40 celcius. We will wait for it to cool on its own and monitor the temperature to create a plot and find the experimental time constant. Later, we can use the heatng circuit we used for the PSL lab and modify the parts as needed to drive a few amps through the circuit. I calculated that we'd need about 6A to get the can to 50 celcius using the setup we used previously, but we could drive a smaller current by using a higher heater resistance.

Attachment 1: time_const.png
13438   Tue Nov 21 16:00:05 2017 KiraUpdatePEMseismometer can testing

I performed a test with the can last week with one layer of insulation to see how well it worked. First, I soldered two heaters together in series so that the total resistance was 48.6 ohms. I placed the heaters on the sides of the can and secured them. Then I wrapped the sides and top of the can in insulation and sealed the edges with tape, only leavng the handles open. I didn't insulate the bottom. I connected the two ends of the heater directly into the DC source and drove the current as high as possible (around 0.6A). I let the can heat up to a final value of 37.5C, turned off the current and manually measured the temperature, recoding the time every half degree. I then plotted the results, along with a fit. The intersection of the red line with the data marks the time constant and the temperature at which we get the time constant. This came out to be about 1.6 hours, much longer than expected considering that onle one layer instead of four was used. With only one layer, we would expect the time constant to be about 13 min, while for 4 layers it should be 53 min (the area A is 0.74 m^2 and not 2 m^2).

 Quote: I made a model for our seismometer can using actual data so that we know approximately what the time constant should be when we test it out. I used the appendix in Megan Kelley's report to make a relation for the temperature in terms of time. $\frac{dQ}{dt}=mc\frac{dT(t)}{dt}$ so $T(t)=\frac{1}{mc}\int \frac{dQ}{dt}dt=\frac{1}{mc}\int P_{net}dt$ and $P_{net}=P_{in}-P_{out}$ In our case, we will heat the can to a certain temerature and wait for it to cool on its own so $\inline P_{in}=0$ We know that $\inline P_{out}=\frac{kA\Delta T}{d}$ where k is the k-factor of the insulation we are using, A is the area of the surface through which heat is flowing, $\inline \Delta T$ is the change in temperature, d is the thickness of the insulation. Therefore, $T(t)=\frac{1}{mc}\int_{0}^{t}\frac{kA}{d}[T_{lab}-T(t')]dt'=\frac{kA}{mcd}(T_{lab}t-\int_{0}^{t}T(t')dt')$ We can take the derivative of this to get $T'(t)=\frac{kAT_{lab}}{mcd}-\frac{kA}{mcd}T(t)$, or $T'(t)=B-CT(t)$  We can guess the solution to be $T(t)=C_{1}e^{-t/\tau}+C_{2}$ where tau is the time constant, which we would like to find. The boundary conditions are $\inline T(0)=40$ and $\inline T(\infty)=T_{lab}=24$. I assumed we would heat up the can to 40 celcius while the room temp is about 24. Plugging this into our equations, $\inline C_{1}+C_{2}=40, C_{2}=24$, so $\inline C_{1}=16$ We can plug everything back into the derivative T'(t) $T'(t)=-\frac{16}{\tau}e^{-t/\tau}=B-C[16e^{-t/\tau}+24]$ Equating the exponential terms on both sides, we can solve for tau $\frac{16}{\tau}e^{-t/\tau}=16Be^{-t/\tau}, \frac{1}{\tau}=B, \tau=\frac{1}{B}=\frac{mcd}{kA}$ Plugging in the values that we have, m = 12.2 kg, c = 500 J/kg*k (stainless steel), d = 0.1 m, k = 0.26 W/(m^2*K), A = 2 m^2, we get that the time constant is 0.326hr. I have attached the plot that I made using these values. I would expect to see something similar to this when I actually do the test. To set up the experiment, I removed the can (with Steve's help) and will place a few heating pads on the outside and wrap the whole thing in a few layers of insulation to make the total thickness 0.1m. Then, we will attach the heaters to a DC source and heat the can up to 40 celcius. We will wait for it to cool on its own and monitor the temperature to create a plot and find the experimental time constant. Later, we can use the heatng circuit we used for the PSL lab and modify the parts as needed to drive a few amps through the circuit. I calculated that we'd need about 6A to get the can to 50 celcius using the setup we used previously, but we could drive a smaller current by using a higher heater resistance.

Attachment 1: cooling_fit.png
Attachment 2: IMG_20171121_164835.jpg
13446   Wed Nov 22 12:13:15 2017 KiraUpdatePEMseismometer can testing

Updated some values, most importantly, the k-factor. I had assumed that it was in the correct units already, but when converting it to 0.046 W/(m^2*K) from 0.26 BTU/(h*ft^2*F), I got the following plot. The time constant is still a bit larger than what we'd expect, but it's much better with these adjustments.

For our next steps, I will measure the time constant of the heater without any insulation and then decide how many layers of it we will need. I'll need to construct and calibrate a temperature sensor like the ones I've made before and use it to record the values more accurately.

Quote:

I performed a test with the can last week with one layer of insulation to see how well it worked. First, I soldered two heaters together in series so that the total resistance was 48.6 ohms. I placed the heaters on the sides of the can and secured them. Then I wrapped the sides and top of the can in insulation and sealed the edges with tape, only leavng the handles open. I didn't insulate the bottom. I connected the two ends of the heater directly into the DC source and drove the current as high as possible (around 0.6A). I let the can heat up to a final value of 37.5C, turned off the current and manually measured the temperature, recoding the time every half degree. I then plotted the results, along with a fit. The intersection of the red line with the data marks the time constant and the temperature at which we get the time constant. This came out to be about 1.6 hours, much longer than expected considering that onle one layer instead of four was used. With only one layer, we would expect the time constant to be about 13 min, while for 4 layers it should be 53 min (the area A is 0.74 m^2 and not 2 m^2).

 Quote: I made a model for our seismometer can using actual data so that we know approximately what the time constant should be when we test it out. I used the appendix in Megan Kelley's report to make a relation for the temperature in terms of time. $\frac{dQ}{dt}=mc\frac{dT(t)}{dt}$ so $T(t)=\frac{1}{mc}\int \frac{dQ}{dt}dt=\frac{1}{mc}\int P_{net}dt$ and $P_{net}=P_{in}-P_{out}$ In our case, we will heat the can to a certain temerature and wait for it to cool on its own so $\inline P_{in}=0$ We know that $\inline P_{out}=\frac{kA\Delta T}{d}$ where k is the k-factor of the insulation we are using, A is the area of the surface through which heat is flowing, $\inline \Delta T$ is the change in temperature, d is the thickness of the insulation. Therefore, $T(t)=\frac{1}{mc}\int_{0}^{t}\frac{kA}{d}[T_{lab}-T(t')]dt'=\frac{kA}{mcd}(T_{lab}t-\int_{0}^{t}T(t')dt')$ We can take the derivative of this to get $T'(t)=\frac{kAT_{lab}}{mcd}-\frac{kA}{mcd}T(t)$, or $T'(t)=B-CT(t)$  We can guess the solution to be $T(t)=C_{1}e^{-t/\tau}+C_{2}$ where tau is the time constant, which we would like to find. The boundary conditions are $\inline T(0)=40$ and $\inline T(\infty)=T_{lab}=24$. I assumed we would heat up the can to 40 celcius while the room temp is about 24. Plugging this into our equations, $\inline C_{1}+C_{2}=40, C_{2}=24$, so $\inline C_{1}=16$ We can plug everything back into the derivative T'(t) $T'(t)=-\frac{16}{\tau}e^{-t/\tau}=B-C[16e^{-t/\tau}+24]$ Equating the exponential terms on both sides, we can solve for tau $\frac{16}{\tau}e^{-t/\tau}=16Be^{-t/\tau}, \frac{1}{\tau}=B, \tau=\frac{1}{B}=\frac{mcd}{kA}$ Plugging in the values that we have, m = 12.2 kg, c = 500 J/kg*k (stainless steel), d = 0.1 m, k = 0.26 W/(m^2*K), A = 2 m^2, we get that the time constant is 0.326hr. I have attached the plot that I made using these values. I would expect to see something similar to this when I actually do the test. To set up the experiment, I removed the can (with Steve's help) and will place a few heating pads on the outside and wrap the whole thing in a few layers of insulation to make the total thickness 0.1m. Then, we will attach the heaters to a DC source and heat the can up to 40 celcius. We will wait for it to cool on its own and monitor the temperature to create a plot and find the experimental time constant. Later, we can use the heatng circuit we used for the PSL lab and modify the parts as needed to drive a few amps through the circuit. I calculated that we'd need about 6A to get the can to 50 celcius using the setup we used previously, but we could drive a smaller current by using a higher heater resistance.

Attachment 1: cooling_fit_1.png
13447   Wed Nov 22 14:47:03 2017 KiraUpdatePEMseismometer can testing

For the insulation, I have decided to use this one (Buna-N/PVC Foam Insulation Sheets). We will need 3 of the 1 inch plain backing ones (9349K4) to wrap a few layers around it. I'll try two layers for now, since the insulation seems to be doing quite well according to initial testing.

 Quote: Updated some values, most importantly, the k-factor. I had assumed that it was in the correct units already, but when converting it to 0.046 W/(m^2*K) from 0.26 BTU/(h*ft^2*F), I got the following plot. The time constant is still a bit larger than what we'd expect, but it's much better with these adjustments. For our next steps, I will measure the time constant of the heater without any insulation and then decide how many layers of it we will need. I'll need to construct and calibrate a temperature sensor like the ones I've made before and use it to record the values more accurately.

13455   Tue Nov 28 16:02:32 2017 ranaUpdatePEMseismometer can testing

I've ordered 4 of these from McMaster. Should be delivered to the 40m by noon tomorrow.

 Quote: For the insulation, I have decided to use this one (Buna-N/PVC Foam Insulation Sheets). We will need 3 of the 1 inch plain backing ones (9349K4) to wrap a few layers around it. I'll try two layers for now, since the insulation seems to be doing quite well according to initial testing.

Kira and I also discussed the issiue. It would be good if someone can hunt aroun on the web and get some free samples of non-shedding foam with R~4.

13482   Fri Dec 15 17:05:55 2017 gautamUpdatePEMTrillium seismometer DC offset

Yesterday, while we were bringing the CDS system back online, we noticed that the control room wall StripTool traces for the seismic BLRMS signals did not come back to the levels we are used to seeing even after restarting the PEM model. There are no red lights on the CDS overview screen indicative of DAQ problems. Trending the DQ-ed seismometer signals (these are the calibrated (?) seismometer signals, not the BLRMS) over the last 30 days, it looks like

1. On ~1st December, the signals all went to 0 - this is consistent with signals in the other models, I think this is when the DAQ processes crashed.
2. On ~8 December, all the signals picked up a DC offset of a few 100s (counts? or um/s? this number is after a cts2vel calibration filter). I couldn't find anything in the elog on 8 December that may be related to this problem.

I poked around at the electronics rack (1X5/1X6) which houses the 1U interface box for these signals - on its front panel, there is a switch that has selectable positions "UVW" and "XYZ". It is currently set to the latter. I am assuming the former refers to velocities in the xyz directions, and the latter is displacement in these directions. Is this the nominal state? I didn't spend too much time debugging the signal further for now.

Attachment 1: Trillium.png
13483   Fri Dec 15 18:23:03 2017 ranaUpdatePEMTrillium seismometer DC offset

UVW refers to the 3 internal, orthogonal velocity sensors which are not aligned with the vertical or horizontal directions. XYZ refers to the linear combinations of UVW which correspond to north, east, and up.

13521   Wed Jan 10 09:49:28 2018 SteveUpdatePEMthe rat is back

Five mechcanical traps set inside of boxes. Red-white warning tape on top of each.

 Quote: Last jump at rack Y2.

13575   Wed Jan 24 13:55:04 2018 KiraSummaryPEMSeismometer can insulation test

Gautam and I set up the insulated seismometer can in the lab today. I had previously wired up the two heaters I placed onto the sides of the can in parallel to get a total resistance of 12.5 ohms and then I wrapped the whole can in 3 layers of insulation (k-factor 0.25). We placed it on a large sheet of insulation as to not crush the wires leading out the bottom of the can. I stuck on one of my AD590 sensors to the inside of the can onto the copper lining using duct tape, though this is only a temporary solution. In the future, it would be nice to have some sort of thermal clamp to secure the sensor to the can. To provide power to the heater circuit board and the temperature sensor board, we got a powerstrip and plugged in two power supplies and a function generator into it. The heater circuit (attachment 3) is powered by one of the power supplies and the function generator, while the temperature sensor (attachment 5) is stuck to the side of the can and is powered by the second power supply. The heater circuit's MOSFET (IRF640, attachment 4) is placed on a metal block and sandwiched between two more to make sure it doesn't move around. The temperature sensor is connected by a long BNC cable to the channels in attachment 6.

gautam: we plugged the BNC output of Kira's temperature sensor circuit to J7 on the AA input chassis in 1X2 - this corresponds to ADC1 input 12 in c1ioo. I then made a "PEM" namespace block inside the c1als model, and placed a single CDS filter module inside it (this can be used for calibration purposes). The filter module is named "C1:PEM-SEIS_EX_TEMP", and has the usual CDSfilt channels available. I DQ'ed the output of the filter module (@256 Hz, probably too high, but I'm holding off on a recompile for now). Recompilation and model restart of c1als went smoothly.

2 bench power supplies are being used for this test, we can think of a more permanent solution later.

**25 Jan noon: Added another filter module, "C1:PEM-SEIS_EX_TEMP", to which Kira is hooking up a second temperature sensor, which will serve as a monitor of the "Ambient" lab temperature. Added DQ channel for the output of this filter module, fixed sampling to 32Hz. Compile and restart went smooth.

Attachment 1: IMG_20180124_124209.jpg
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Attachment 6: IMG_20180124_124156.jpg
13581   Thu Jan 25 08:27:25 2018 SteveUpdatePEMearthquakes

M4 local earthquake at 10:10 UTC    There is no sign of damage.

....here is an other one.........M5.8 Ferndale, CA at 16:40 UTC

Attachment 1: M4_local_eq.png
Attachment 2: M4.png
Attachment 3: M5.8Ferndale_CA.png
13582   Thu Jan 25 12:41:18 2018 KiraUpdatePEMSeismometer can insulation test

We started the actual heating test today and it seems to be working so far. Hoping to heat it to about 40C. We also set up another temperature sensor to measure the lab temperature and connected it to J7, bottom.

13584   Thu Jan 25 14:58:20 2018 KiraUpdatePEMSeismometer can insulation test

After almost 3 hours the temperature rose by about 3.5C. Seems a bit slow, but we can drive it more if necssary. The heating curve itself is exponentiial, which is a good sign.

 Quote: We started the actual heating test today and it seems to be working so far. Hoping to heat it to about 40C. We also set up another temperature sensor to measure the lab temperature and connected it to J7, bottom.

13585   Thu Jan 25 16:39:09 2018 KiraUpdatePEMSeismometer can insulation test

The final temperature reached in about 4.5 hours is 30.5C, while the starting temperature is about 24C. I can't seem to screenshot the data for some reason.

Also, I will calibrate the lab temperature sensor to Celcius in the near future so that we would have a working sensor inside the lab.

Quote:

After almost 3 hours the temperature rose by about 3.5C. Seems a bit slow, but we can drive it more if necssary. The heating curve itself is exponentiial, which is a good sign.

 Quote: We started the actual heating test today and it seems to be working so far. Hoping to heat it to about 40C. We also set up another temperature sensor to measure the lab temperature and connected it to J7, bottom.

Attachment 1: HeaterTest.png
13598   Thu Feb 1 16:09:13 2018 KiraUpdatePEMSeismometer can insulation test

After taking the measurements, calibrating them (approximately), and filterting them, I created the following plot. The exponential fit is quite good, as the error is not more than 0.03 C. I used the python function curve_fit in order to get this, and it gave me the time constant as well, which came out to 0.357 hr. From my previous calculations here, I plugged in the values we have (m = 12.2 kg, c = 500 J/kg*k, d = 0.0762 m, k = 0.26 W/(m^2*K), A = 1 m^2), and got that

$\tau = \frac{mcd}{kA}=0.496hr$

This is a bit off, but it's probably due to the parameters not being exactly what I supposed them to be, and heat losses through the bottom of the can.

Attachment 1: cooling_fit.png
ELOG V3.1.3-