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Entry  Wed Aug 2 03:35:18 2017, Zach, Electronics, SiFi, Current driver range increased to 200 mA SiFi_current_driver2_coarse_response_8_1_17.pngSiFi_current_driver2_fine_response_8_1_17.pngR31.jpg
    Reply  Wed Aug 2 08:31:58 2017, Johannes, Electronics, SiFi, Current driver range increased to 200 mA 
       Reply  Wed Aug 2 17:23:48 2017, Zach, Electronics, SiFi, Current driver range increased to 200 mA SN104978_PvsI.pdf
    Reply  Thu Aug 3 18:06:05 2017, Zach, Update, SiFi, More system characterization measurements (laser drivers, heads) SiFi_laser_PvsI_8_2_17.png
Message ID: 1652     Entry time: Wed Aug 2 03:35:18 2017     Reply to this: 1653   1658
Author: Zach 
Type: Electronics 
Category: SiFi 
Subject: Current driver range increased to 200 mA 

One of the things I would like to have is a detailed characterization of my setup, both for easy reference and for my thesis. A natural place to start is the laser drivers (D1200719).

In getting ready to take some measurements on them, I remembered I've been wanting to increase the current output range from 100 mA to 200 mA, since the turn-on current for the lasers is relatively high and I could use some more optical power.

All that required was to change R31 from 100 ohms to 50 ohms (which, as seen in the linked schematic on the DCC, is now the standard value for that component). Unfortunately, this resistor is a TO-220 package, high-power unit, which is hard to come by. After a long hunt in Downs, I found exactly two.

Here are the knob -> current responses of current driver #2 (S1500267) after the modification:

 

(The coarse-knob contribution has been subtracted from the fine-knob data)

So... where's #1? Alas, I actually did this mod on #1 on Monday night, but the thing didn't behave properly after it and I'm still looking into it...

 

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