Piggybacking NPN Transistors
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- เผยแพร่เมื่อ 17 ก.ค. 2020
- When working with a guitar pedal circuit that requires low gain transistors and you don't have Germanium ones sitting around, this little trick might give you what you need. Good for Fuzz Face and Tonebender style fuzzes.
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I’m glad the information wasn’t completely lost to time. Somebody has been needing to do a video on this technique for years! Bravo :D
Sweet! Your videos are getting better by the day. Excellent!
Would love to see more videos like this. Thanks for the great content
Very cool! The 2n3904 is such a great transistor, I feel like it's often underappreciated in diy fuzzboxes
They are used to great effect in the woolly mammoth and shoe pixel fuzz.
BASS player here, WOOW!!! Sounds like germanium. I have a Oner ( brazilian hm-2 ) love the silicon diodes, more like deep frying, quite different to those popular germaniums.
Thanks for all the info.
Sounds very interesting. I may try this once I finish my EZ fuzz circuit.
2n3904 pairs with its compliment 2n3906 and most have a complimentary NPN PNP pair with exact specs to make Complimentary Darlington. Piggybacking is using a high gain to make low gain.. The opposite idea.. Might be useful if you want to make an HFE of 6.
When running a Sziklai theres a resistor used similarly I think I last used 1k. Putting a variable resistor there would help driving a Germanium paired Sziklai..
I like the way your taking this.
Neat trick! Thanks for sharing!
This is gold. Thank you so much
El sonido me encanto. Excelente.
Hello Kevin, Really good tutorial, demo and explanations. I'm glad to say I have been a sub for many years and have always enjoyed the channel, plus learning a lot about pedals. I hope Australia and especially the animals are recovering from the devastating wild fires, it was heart breaking to see. Say hey to Paul. Great content, channel. All the best from Oregon, USA, Cass.
Who is Kevin?
Hi Erik, Sorry, I got the name wrong, Kevin was supposed to be you. Be good, C.
Great vid! Keep going!
Nice one
Dear DIY Pedals, I just found your youtube channel and I am hooked. Thanks for that! Reason I found your website is because I am trying to make something but I'm not sure if its possible or how to do that. I currently have one expression pedal with a trs output. I have multiple pedals with expression functions which take an trs input. So far so good. What I want to build is some sort of signal splitter with 1 input and 3 outputs (and corresponding leds) so I can decide which effect i can stear with the expression pedal. So when I stomp switch one effect 1 will be steered by the expression pedal. When I also stomp switch 2 effect 2 will also be steered. etc etc. Can you give me some advise or tips?
Thank you. I have much fun inspeared by your videos. I build this kind of fuzz with bc109b and compare with existing germanium pedal with germanium transistor fuzz face i build from salvaged parts (unmached transistors, hfe ~105 and 110, average leakage, but good sounding for my needs). I did not like "cleaning", so i switch 100p to 170p film caps, silicon fuzz is a bit softer in "cleaning" than germanium circuit. "Right" value could be in between?
Hi. This video is great. As I understand it, the first circuit is the piggybacked transistor 'tester' circuit. Is that correct and R1 and R2 are ommited in the FF circuit as they are not needed. Have you experimented with simulating leakage at all. I found a comment on a forum from RG Kean saying to add a germanium diode between the new collector and base (where you have the high-roll-off cap). Have you explored this at all?
A vIdeo about amz diodes warp would be Nice
Cool video. I say just build a Marshall Supa Fuzz and call it a day.😂
I'm going to try this idea with a Big Muff circuit.
I realize I'm late to the party but this is very helpful. I've breadboarded a few different Fuzzes and trying to decide on transistors, All I've got are higher hfe BC108s and 9s and 3904s. In this videos the breadboard set up is to test combinations. Essentially you fidd a resistance value and join the 2 transistors at the base and put resistor value between the 2 emitters? thats it ?
Could you do a video on how to read the schematic and put it onto a breadboard? I'm new to building and I'm quite confused on how to read it well
He already made this video
Great vid, more experiments in the field of fuzz. I bought the unshaven fuzz pcb with footswitch pcb, in a deal you had. I don't play guitar, I make Industrial Dub and run an open mic night for ambient. The pedal has synth like tone and breaks up horribly, I love it, I did manage to squeeze it into the smaller enclosure, just, lol. I've messed around with the 7min fuzz, your design, and others, with various transistors, this Bazz Fuss, doesn't seem to do anything. Does this only work with guitar tones and impedance? Or should it be useable with most sound sources? Keep up the good work.
Usually, the Bazz Fuss is more of a lower gain fuzz due to it only having the one stage and typically with only a single moderate gain transistor. Also, with its single diode, it does have some good level of stability, and so it isn't as "splatty" as the Unshaven was designed to be. If gain is what you are looking for, changing the NPN transistor to an NPN darlington transistor of significantly higher gain, will help with that. Another trick is to just place two bazz fuss circuits back to back. If you look at the Unshaven, you can see this idea expanded upon. Basically, it's 3 Bazz Fuss circuits back to back, with the diode removed from each and in its place, a large value resistor.
@@erikvincent5846 cheers Erik, I'll have a look at that, thanks. I have a load of modified LM386 pre-amps, that I sell with high response contact mics, electromagnetic field "sniffers" and cables. These tend to clip in a gnarly way, I'm looking at softening and expanding on this for my low gain "devices".
Hey curious to know. Where would one measure the variable gain after removing the 2.472k and 2.2M resistors?
Maybe off the 33k and Q2 bias trim?
Thanks for the video. This is cool.
Great video! Thank you! What software are you using for analysis?
I was using Fritzing for the breadboard design and EAGLE for the circuit design. Though I didn't use it here in the video, I do use LTSpice a lot.
OMG this sustian is amanzing
The BC108C would work on this circuit too? I'm trying to measure the gain but the DMM shows 8.5v. With a 1M resistor on the place of the 100k pot I get the same 8.5v. On diode testing I get 0.764 on B-E reading, but on B-C I don't get a reading or short.
Watching this while checking gain on NPN germanium transistor that I just bought in bulk, damn, I should save all my money, from 100pcs I only manage to get 13 transistor on the range of 80-130, mostly under 30 which I'm not sure what should I do with them, lol.
I actually have same experience with PNP, barely 5% from the lot is usable.
How would i adjust the schematic to use this principle on PNP transistors? Just put them in watching B/C/E is correct?
Please how do i connect the 2 jacks and the stompswitch, please i am a begginner. Many thanks!
Cool trick now do it with a moog transistor ladder filter.
That's going to get really messy, really quick.
Just getting started... Right now the only transistor I have on hand is 2N3906 (PNP). Am I reading the datasheet correctly in that it has a gain of greater than 250 Mhz?
You would be looking for hfe
Gain is the ratio IC/IB or hfe.The frequency range of transistor is the bandwidth.
Thanks for this vid and all the hard work! Question: Is this what is called a "Push-Pull" design? or would that involve Both an NPN AND a PNP transistor?
A Sziklai Pair is more of a complementary feedback design. So in a generic way of looking at it, the base of the two transistors (NPN and PNP) are not tied together and the pair together control both the tops and bottom of the sine wave. A Push-Pull, like in a Class B amplifier, has the bases of both transistors tied together. Further, the NPN transistor only controls the positive half of the sine wave, while the PNP transistor only controls the negative half of the sine wave.
@@erikvincent5846 Ahh thanks. This appears to be simpler and very clever way to use low gain transistors. Just found you yesterday, great stuff tho right off the bat, as they say. Thanks!
@@Bob-Whiting Welcome to the channel. If you have any other suggestions or questions, let us know and we'll see what we can do.
I have a crap pile of old germanium transistors that a dying engineer gave me because he knew I was a builder. Main problem is that they are ancient. Should I even bother trying to use them, as they are all probably whiskered up, or should I give them a shot?
You also have me wondering what an old Radio Shack pack of 2N3904s or 2N2222s would sound like as well. The HFE on those transistors were all over the place :D.
Most likely shot. Best to box them up and send them to me! 😅
Aren't the 2N2222 noisy?
As for the Germanium's, I'd say, try them...It's not like you're trying to get HiFi performance out of them. Might be worth adding an adjustable bias control as that can have quite an effect sometimes.
Well, if you have NPN, usually they did okay, as far as germanium leaking is concerned, but their HFE are usually "too low to be used for anything meaningful". I would disagree, as if the leakage is low, either in a pair of them, or a silicon/germanium pair, you can make Darlington pairs that might be pretty cool. If you have PNP germanium, then I'd suggest pairing them with low HFE silicon NPN transistors (or a piggyback set) and make a Sziklai pair. That way, it becomes a "NPN" transistor that retains the germanium sound, but takes on more of the silicons characteristics and low leakage.
@@Bishka100 Exactly what I was thinking, Bishka. Also, since this is a Fuzz application, I wonder if it would even matter if they were noisy? Maybe it will add to the "fuzz" or something :D.
I thought about going really overboard and adding a bit of tone adjustment, doing so by reverse biasing a diode to act as a varicap. Hey, one more adjustment can't hurt :D. An actual varicap would probably work best, but I'm thinking about just trying various diodes and see how she plays.
@@erikvincent5846 Man, that is a great idea. What I'm really looking for is maximum flexibility while testing, and maybe I'll be able to dial in something that might sound appealing in certain situations -- or maybe not :D .
I also watch Shango066 here on TH-cam. He does a lot of old TV and radio repair. He has a video or 3 on using Russian germanium transistors that you can get for a decent price, and they even look to be old milspec components. If I remember correctly, he bulk orders them on e-Bay.
Definitely worth checking out his videos, and he's very entertaining, plus he's a great trouble-shooter.