Fuzzcentral Silicon Axis Face

[Crawf]

Hi, I`m building the Silicon Axis Face and was wondering if other transistors would work apart from the BD139 and PN2369A and if so which would be the best match, i can get the the BD 139`s but the PN2369A`s seem harder to get locally, thanks Crawf.

[petemoore]

  See GEO Technology of the FF, Picking transistors for the FF.
  Also piggybacked FF's.
  Trimpot Q2 collector is a common move, as is socketting both transistors, for first FF, or second, when you wanna tune it, socketting also the input cap.
  Out put cap, that can be re-soldered to the pot, paralleled or seriesed with an additional cap, or just plain socketted too.
  FF's can be messed around with to a very great degree.
  Also you may want more or less R on the gainpot. 1kpot + a less than 1k resistor seriesed between gainpot and ground, may oscillate, depending on everything else including transistor gains. You may like smaller gainpot value with higher gain transistors/vice versa.
  Re-bias Q2 collector to ~1/2v or by ear after every Q swap.

[burnt fingers]

Yu can use 2n3904, 2n5088,2n5089, 2n2222,2n4401 and probably a whole lot of others.  The sound will vary depending on the tranny. 

The 3904 would probably be the best bet but use sockets for the trannys and just use your ears to determine which one is best for you.


Scott

[mojotron]

The pn2369a/pn2369/2n2369 should be easy to find on line - these are ideal because the gain on these is right around 100. I really like the 2n3904 or a 2n5088 in the Si Axis Face. I have used a 2n5088 for Q1 and used a 500-2k source resistor to bring down the gain - a pot works well for this as well.

[Crawf]

Thanks Guys, I completed the Fuzz tonight, made a few basic wiring errors but got there in the end, i tried a few types of transistor but finally ended up using two BD139`s which sound good at home at low volume but i`ll see what it offers at the next gig and if its not what i want i`ll try something else, i`ve socketed them anyway so swaping is no problem.
I`ve only began etching my own boards and this one worked at once so that made it all the more worthwhile,anyway thanks for all your help once again, Crawf.

[brett]

Hi
low gain transistors have substantial advantages in the fuzzface.  I've also found the BD139 is a really good device.  Someone might swap you a 2369A for a 139 or something else so you can try it in Q1.  It'll have even less gain than the BD139 and load yoyr pickups even more.  I'm in Australia, so it's not worth the postage from here, but someone in the US might slip one in an envelope for you ??
cheers