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Entry  Thu Oct 1 13:12:41 2009, Koji, Update, MZ, MZ Work from 13:00- 
    Reply  Thu Oct 1 19:04:05 2009, Koji, Update, MZ, MZ work done (Re: MZ Work from 13:00-) MZ_PZT.pdf
Message ID: 2038     Entry time: Thu Oct 1 19:04:05 2009     In reply to: 2035
Author: Koji 
Type: Update 
Category: MZ 
Subject: MZ work done (Re: MZ Work from 13:00-) 

MZ work has been done. I did not change anything on the circuit.

Recently we observed that the MZ PZT output was sticking at a certain voltage. I found the reason.
Shortly to say "we must return the PZT Ramp offset to 0, after the lock"

I am going to write a MZ auto lock script someday, to do it automatically.


According to the resister values used in the circuit, the PZT HV output voltage is determined by the following formula:

V_PZT = 150 - 12 V_ctrl - 24 Vramp

Here the ramp voltage Vramp moves from -10V to +10V, the feedback control voltage V_ctrl moves from -13V to +13V.
The baseline offset of 150V is provided in the circuit board.

When V_ramp is 0, V_PZT runs from 0 to 300. This is just enough for the full scale of the actual V_PZT range,
that is 0V~280V.

If any Vramp offset is given, V_PZT rails at either side of the edges. This limits the actual range of the PZT out.

This is not nice, but is what happened recently.

Quote:

I will investigate the MZ board. I will unlock MZ (and MC).

 

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