Firefly UPDATE

[Doug H]

For all the Firefly builders out there:

I updated the Rev 3 schematic. I added an alternate power supply wiring scheme for center-tapped power transformers. Also, check out C12, parallel to the plate resistor in the booster stage. I accidentally left out this mod when I first posted R3. It smooths out the highs a hair when the booster is on.

The schematic can be found on my Firefly page:

http://home.cfl.rr.com/dbhammond/ff.htm

Thanks,

Doug

[Alex C]

Hey Doug (or anyone else who knows what they're doing), I was having the same problems as Paul (voltages reading in the 400-550 range at filter caps-  B+).  I used the 269EX and the configuration shown in the second diagram on your update page, except I switched the center tap to ground with the standby switch as I did with the same transformer on my AX84 P1 http://ax84.com/media/ax84_m37.pdf  

I only had a short time to mess with it this weekend, so I didn't get a chance to thoroughly test things.  I don't see how this is different from the AX84 method or the second diagram on your site.  I am fairly ignorant aobut the things that are basics for you guys, but I've gotta learn somehow.  Thanks for your patience so far.

Alex

[Doug H]

I never noticed stdby wired that way in the P1 before. I would recommend grounding the center tap and putting the standby switch between the rectifier and the filter caps.

Doug