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i'm on a roll... the kgsshv


kevin gilmore

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its getting pretty tight...

 

http://gilmore.chem.northwestern.edu/kgsshvcarbon.jpg

 

laying the rest of them horizontal is going to be a bit of trouble.

 

For those who still have c2240 and c2705, are the newer pzta part subs better?

 

Also, if one used the 1486 would it need to be heatsinked given your comments on the stn9360?

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you can get your own one-off done, won't break the bank

 

I think JoaMat is the only one with a working unit at this point, maybe Kevin? Beta tests are open, register at http://gilmore.chem.northwestern.edu/boards/

 

I have a set of the boards prior to these upgrades if you're interested. I think it's equivalent to the version that Birgir posted earlier in this thread

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Mine are ready for testing but other stuff has taken over for a while.  Might even be pushed back further for the new Megatron PCB. 

 

As for SMD, if you want resistors that are equal to the RN60D's then they are 1$ each or even more.  SMD was never designed for HV in mind... 

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Just checking the board/schematic around the servo.  Looks good.

 

You can change the label for PZTA28 to PZTA06 (same pin out) or some other NPN.  Keeping the MJF15030 part is a good idea.

 

Also, the 5K pot should probably go down to a 1K (or 2K) POT and also change the 20K to a 24K (TBD) resistor.  Varying by 400 ohms moves the output about 6 - 8 volts.  It's just a matter of making it have enough range, but not being too sensitive.

 

The last thing is that I currently have 2pF caps across both legs of the 2 x 1M resistors on the KGST build.  I'm not sure if this helps or hurts.  I'll try pulling them out this weekend.  I'm hoping the 220pF cap can manage any possible oscillation.

 

I'll confirm the rest of the board then built the LTSpice model next.

Edited by Kerry
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certainly can replace the reference with a to92, current datasheet does not list the pinouts.

 

I did trim the emitter resistors to 25 ohms, so there is still about 9v on the servo.

 

But will change values to the final parts when we all decide what those are.

 

also added a pot in series with the 20k resistor to adjust the dc to exactly zero.

 

the 25 ohms decreases the thd a significant amount at 20khz because of the

added gain.

 

let me know which parts and values to change.

Edited by kevin gilmore
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