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--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 12:46, 9 December 2014 (CST)
Another day, another crack at circuit debugging..
-tried putting inverter before the lockbox, that doesn't seem to fix it.
-invert fast feedback?
--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 16:01, 8 December 2014 (CST)
Re: circuits One issue is coming into focus: the source of the 10s of kHz noise on the circuit rails, that seems to bleed through into the error signal. It appears that its origin is the heater in the lm399s. I'm going to try running them without the heaters and see what happens. Running without the heaters squelches the kHz level noise and doesn't seem to prevent any ffb locking. Maybe this is the way we should run them.
* Strung together the PDH electronics and it worked! well we could see an error signal anyway. Error signal looks pretty much like the Black paper. Did not have to struggle with the phase-shift in order to get a proper-looking error signal.
* Stuck the lock-box in the set-up. We can turn on the fast feedback and see the central resonance broaden, as we expect, as we zoom in on the peak (i.e. adjust the piezo DC and shrink the ramp), the fast feedback intermittently locks on its own. This is pretty encouraging, so at least the FFB seems to be working. However, when we turn from ramp to lock, it doesn't lock. There is a problem with the slow (piezo) feedback branch. Probably the first thing to look at is the switch.
--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 22:13, 2 December 2014 (CST)
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