BC183/BC184 Sandspur/Sunface

giovanni

Well-known member
Hey guys, I wonder if I could use the Sandspur board with BC183 or BC184 transistors? Analogman makes both BC109 and BC183 versions of the Sunface and I suspect the rest of the circuitry to be quite similar if not identical (they sound extremely similar). The BC184 is like 8c on Tayda, compared to $1 for the BC109, so you see where I am going with this. I would also consider other alternatives, of course.
 
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Chuck D. Bones

Circuit Wizard
Pay attention the the suffix; the letter denotes HFE grade. A is lower HFE, C is higher HFE. When in doubt, consult the datasheet. HFE influences the tone, particularly Q1 because HFE determines the input impedance & biasing. The CLEAN & SUNDIAL knobs should make it possible to accommodate a wide range of transistors.
 

giovanni

Well-known member
Pay attention the the suffix; the letter denotes HFE grade. A is lower HFE, C is higher HFE. When in doubt, consult the datasheet. HFE influences the tone, particularly Q1 because HFE determines the input impedance & biasing. The CLEAN & SUNDIAL knobs should make it possible to accommodate a wide range of transistors.
BC184 have a crazy minimum hfe of 240. Is that gonna be too much?
 

Chuck D. Bones

Circuit Wizard
Who knows? Try it and see. 240 is not all that high for silicon.

The higher HFE will increase the input impedance and reduce Q2's collector current. Whether it sounds better, worse, or the same is up to your ears.
 

Big Monk

Well-known member
BC184 have a crazy minimum hfe of 240. Is that gonna be too much?

Depends on what you want. What are you going for with this pedal? Germanium Soundalike? Medium gain late 60s/early 70s BC183? Higher gain BC10x?

You can use gain reduction techniques if need be to accommodate basically any hFE.
 

HamishR

Well-known member
BC184 have a crazy minimum hfe of 240. Is that gonna be too much?
What's the hfe of a BC108C? it's probably not that different. I've built one with the BC108 and it didn't knock my socks off. There's no particular mojo with a BC108 as far as I can see. Or hear. Some of my favourite Big Muff style pedals have been made with much lower hfe transistors than specced and I much prefer the sound. A Skreddy P19 with 2N3904s sounds amazing.
 

HamishR

Well-known member
BTW if you do use the BC183 make sure to check the pinout for the ones you're using. I think it's the BC183L which has a different pinout, but it has been a while since I used them.
 

Mcknib

Well-known member
BTW if you do use the BC183 make sure to check the pinout for the ones you're using. I think it's the BC183L which has a different pinout, but it has been a while since I used them.
Yep Tayda have them all in the same listing

I think there were a few troubleshoots where people had ordered the BC183 only to get the 183L which has a completely different pinout with the collector being the centre pin and base an outer pin
 

giovanni

Well-known member
Yep Tayda have them all in the same listing

I think there were a few troubleshoots where people had ordered the BC183 only to get the 183L which has a completely different pinout with the collector being the centre pin and base an outer pin
Good thing I have a transistor tester!
 
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Big Monk

Well-known member
Yep Tayda have them all in the same listing

I think there were a few troubleshoots where people had ordered the BC183 only to get the 183L which has a completely different pinout with the collector being the centre pin and base an outer pin

You’ll notice this is likely the case when you see vintage units with the center lead with a piece of tubing on it and bent over the others.
 

Lowtide

Member
this was one of my first builds - i played around so much with basically every transistor i had that i wore out two sockets. was a good way to see what effect hfe/biasing had on a fuzz face circuit. the germanium version is one of my favs
 
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