Need help with components

Fuzz Wizard

Member
Hello, I'm back again to ask for help with sourcing some parts for my next few builds. I was hoping to get some help sourcing / substituting some parts. I wanted to get the order in today to smallbear to make use of the sale. Thanks in advance.

  • For Q2 on the War Scythe, it lists AC176. I can't find this transistor anywhere, and other threads said to swap it out for another NPN transistor. What should I replace it with?
  • For Q4-5 the War Scythe lists 2n1308, but I was thinking about ordering some 2n1306s for replacement. Should this work?
  • The Mofeta Preamp requires some 562k resistors. Where can I find these, and if I can't, what should I replace it with?
  • Tayda is out of the solder lug footswitches, should the through hole work if I'm using the breakout board.=?
 
For mine, I used MP38a in Q4-5. You can use 2N1306. They are lower binned than 2N1308 but they'll work fine. That side isn't too fussy.

For Q2, an NPN Ge with a bit of leakage is better. If there isn't enough leakage, you'll get gating.
 
For germanium transistors the part number is kind of unimportant, but the gain and leakage are what matters. Sometimes it takes some research (to see what range of values works in the circuit) plus some trial and error (to find a set of transistors that sound good to you).

It's also good to learn how to measure gain and leakage so you know what you're working with, because you'll probably need to buy batches of transistors and find what works (such as the one described here www.geofex.com/Article_Folders/ffselect.htm).
 
For germanium transistors the part number is kind of unimportant, but the gain and leakage are what matters. Sometimes it takes some research (to see what range of values works in the circuit) plus some trial and error (to find a set of transistors that sound good to you).

It's also good to learn how to measure gain and leakage so you know what you're working with, because you'll probably need to buy batches of transistors and find what works (such as the one described here www.geofex.com/Article_Folders/ffselect.htm).
So I'm still a little confused about what to order. Are you saying I should just pick a random NPN ge transistor and see if it works? That seems like it would get expensive fast. Should I just buy a random part number and cross my fingers?
 
So I'm still a little confused about what to order. Are you saying I should just pick a random NPN ge transistor and see if it works? That seems like it would get expensive fast. Should I just buy a random part number and cross my fingers?
I'd look at the data sheet to see what the expected gain ranges is, then match it to the circuit you are building. You can piece-meal these transistors or buy 50-100 and measure/sort them yourself. It really depends on how many you think you'll need.
 
I'd look at the data sheet to see what the expected gain ranges is, then match it to the circuit you are building. You can piece-meal these transistors or buy 50-100 and measure/sort them yourself. It really depends on how many you think you'll need.
I probably won’t need many, this is the only project I’ve been looking at that has GE transistors. I’m hoping to find something useable from stompboxparts, but it’s not looking good considering I need something with some leakage.
 
Okay, the DB says I have 20 AC127s on-hand, varying in hfe & leakage. I'd need to verify a particular one....I'm lazy when it comes to updating this 🤣

Pick one out and I'll send it to you.

View attachment 37026
You are truly the greatest of all time. I need something with some leakage, but I’m really not sure how much is too much or too little. Is .199 considered “leaky”? I’m leaning towards the first on the list.
 
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You are truly the greatest of all time. I need something with some leakage, but I’m really not sure how much is too much or too little. Is .199 considered “leaky”? I’m leaning towards the first on the list.
Let me make sure it's still there. I'll also send a few with different measurements as well so you have an idea of how they effect things. I've still got your address so I'll get them mailed. I have a few other things going out tomorrow.
 
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So I'm still a little confused about what to order. Are you saying I should just pick a random NPN ge transistor and see if it works? That seems like it would get expensive fast. Should I just buy a random part number and cross my fingers?
Yes pretty much. Some sellers will sell you ones in measured range so you can be more sure--but they usually cost more if they're presorted. That's the best way to go if you know exactly what you need, and I've done that for a couple of pedals.

More recently, I just ordered some and crossed my fingers: I wanted 3 specific ranges so I ordered 6. 2 came within the range, 1 was close enough to use, and the others will be set aside to try in some future circuits.
 
I picked out a couple of others to try;
A second AC127 w/o heatsink hfe @ 85ß, leakage .049mA
1T404 hfe @ 53ß, leakage .112mA

DopFYbI.jpg
 
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