# Sandspur Transistors



## Billyhank (Jan 7, 2021)

Hi!
Im getting set to build a sandspur and had a question about the transistors. I know with the Sunflower the transistor hFe is important but I’m not 100% how important the BC108 hFe is in the sandspur circuit.
I don’t want to have to swap transistors if I can avoid it.
Anyone have any advice or knowledge about this?
Thanks!


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## Mcknib (Jan 7, 2021)

I don't think it's critical with zero leakage silicon transistors the man himself uses the BC108 and BC109 A,B and C

C being the highest hFE 

A Group 125-260
B Group 240-500
C Group 450-900


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## Billyhank (Jan 7, 2021)

Awesome. Thanks! I messed up a couple of the Sunflowers because I was new and didn’t know what I was doing. Lol. Just wanted to make sure I didn’t do it again.


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## Doppler (Jan 9, 2021)

Hi 

I'm looking to Sunfaces circuits for a while, I played a bit on breadboard with it, but never had the luck to get a proper Sunface in my hand to compare, also I'm a beginner and still don't have a scope for indepth analysis. ^^'  So take this with some salt, sources I'm referring to looks solid to me but, I'm no expert... (thanks to correct me if I'm wrong)

Usually you need a lower hFe in Q1. For instance first germanium Sunfaces (like legendary NKT275) had Q1 70 / Q2 90 for smooth ones, to Q1 100 Q2 130 for fuzzier ones (and lot of in between). SIlicon versions went of course beyound these levels. But like with the Fuzz Faces it is not just about hFe, the whole component equilibrium is important. Whatever transistor you want, you need to to get the right amount of voltage on each transistor collector (depending on each specific characteristic of employed transistors), witch implies to adapt resistors. That's because of the "voltage feedback biasing" on witch Fuzz Faces are very dependent. Sunface helps a lot with the bias pot, but still, important optimization can be done understanding what is going on.

It looks like a simple pedal at first glance, but it is in fact a rabbit hole. Breadboarding quite a bunch, and/or building the PCB with strategic sockets to allow useful easy swaps (transistors, bias pot and resistors) is very, very, important to find great sounds (and also learn a lot on the way for future projects). And only then, if you really need a soldered unit to feel safe during chaotic gigs, transfer your favorite recipe into an other dedicated board.

A good introduction :








						Coda Effects: Analogman Sunface Build
					

Learn more about electric guitar related electronics: DIY guitar pedals, from fuzz faces to delays and reverb, cables and circuits theory




					www.coda-effects.com
				




Fuzz Face Bible :


			The Technology of the Fuzz Face


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## spi (Jan 10, 2021)

I've built a couple of silicon fuzz faces, and experimented with a few combinations of transistors.   The favorite combo is 2n2369 in Q1 and 2n2222 in Q2.  



Billyhank said:


> I don’t want to have to swap transistors if I can avoid it.



I recommend socketing them if you can, then it's easy to swap if you want to experiment.  
If not you can breadboard the circuit to audition different combos.


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## uranium_jones (May 8, 2021)

Hey, I'm going to resurrect this thread instead of posting my own nearly identical thread... I'm specifically after that piercing "Time" solo tone, so I am thinking of either using B109Cs for both, B108s for both, or a mix of the two. Do I care about the hFE values for these since they're silicon? What about the ratio between Q1 and Q2? I just bought some sockets so I can swap things around, but I would like to know how different electrical aspects should affect sound as well, rather than taking wild shots in the dark.


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## fig (May 8, 2021)

Yeah, Q1 feeds the base of Q2, so gains are critical, whereas leakage is null.

Check the ranges above from @Mcknib . Those are what you're affer


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