Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Preamps and Effects => Topic started by: LJN on January 05, 2016, 11:03:40 PM

Title: Are these AC128s useable?
Post by: LJN on January 05, 2016, 11:03:40 PM
Hi, everyone. I recently purchased a bunch of AC128 transistors on eBay and I was wondering which fuzz circuits should sound good with them. The hfe on them varies. The lowest is 58 and I believe the highest is 75. The leakage on most of them is 0.06 ma with some having 0.12 ma. I used some in my Tone Bender mk. II clone, but it sounds too smooth. I also used them in a Tone Bender mk. 1.5 with slightly better results. I can't seem to get any of them to work in a fuzzrite circuit, though. I'm wondering if they're useable or if I just wasted my money. Thanks.
Title: Re: Are these AC128s useable?
Post by: J M Fahey on January 06, 2016, 09:46:42 AM
What you measure sounds reasonable, they should work.

Please post the fuzzrite schematic .

Title: Re: Are these AC128s useable?
Post by: LJN on January 06, 2016, 05:03:38 PM
I don't have any way of posting schematics. I tried every one of those transistors and the most I got from it was a very low output with a short, gated, fatty decay.
Title: Re: Are these AC128s useable?
Post by: J M Fahey on January 07, 2016, 10:13:53 AM
Well, first you google and open it, copy the link/page address, click the "smiling yellow TV screen"  on the toolbar above and paste the link, then the schematic opens in this page and we can all see and discuss it.

Otherwise it's a guessing game.
Title: Re: Are these AC128s useable?
Post by: LJN on January 07, 2016, 02:39:49 PM
Okay. I'll see if I can do that.
Title: Re: Are these AC128s useable?
Post by: LJN on January 07, 2016, 03:17:07 PM
The schematic is on the mosrite forum. I can't get my phone to post it.
Title: Re: Are these AC128s useable?
Post by: DrGonz78 on January 08, 2016, 12:03:36 AM
Most of the Mosrite Fuzzrite schematics appear to use NPN type transistors. I did find one I am attaching on the mosriteforum.com website.

Also I am posting the link to Fuzz Central, which shares the ssguitar in the web address. Plenty of Fuzz schematics there...
http://fuzzcentral.ssguitar.com/schematics.php
Title: Re: Are these AC128s useable?
Post by: LJN on January 08, 2016, 01:33:15 AM
Yes, that's the one. I was wanting to build it because it's the circuit that was used by Iron Butterfly.
Title: Re: Are these AC128s useable?
Post by: LJN on January 22, 2016, 03:29:04 AM
Hi, everyone. Well, after some debugging of a few wiring mistakes (not sure how that happened) , I now have a wicked sounding germanium Fuzzrite. It's sporting two of those AC128 transistors. Q1 read as having a hfe of 193 and I believe Q2 is around 60. The only part that's missing is the power filter cap, but the pedal works just fine without it. It nails the "Psychotic Reaction" Tone perfectly!
Title: Re: Are these AC128s useable?
Post by: LJN on March 03, 2016, 07:36:42 PM
Would it be possible to make a tremolo circuit with some of these low gain germanium trannies?
Title: Re: Are these AC128s useable?
Post by: Enzo on March 04, 2016, 04:14:43 AM
They are just transistors, you can make any transistor circuit you want with them.
Title: Re: Are these AC128s useable?
Post by: LJN on March 04, 2016, 04:44:07 AM
Be for I try any experimentation with my remaining stock, I'm gonna try to get one of those solderless breadboards. That way I won't go through so much solder. Thanks.