Mosfet boost , first pedal

[jeff_e]

It's an AMZ mosfet booster circuit with parts I had on hand, in kind of a huge box , but it's been sitting on my shelf. Set up for battery power only, some of the resistors are 1 watt(not required) and the crappiest (paper and glue?) perf board. But it works well, and has a chicken head knob from my grandpa's old parts stash. I found a good diagram for the switch, the input is grounded when the boost is switched out.

 

[guitar_paul1]

What MOSFET did you wind up using? I love the old knob and the substantial orange box.

 

[jeff_e]

Thanks .
I did have a BS170 around.

 

[ahiddentableau]

Nice work. How are you liking the circuit?

 

[ping-ping-clicka]

It's an AMZ mosfet booster circuit with parts I had on hand, in kind of a huge box , but it's been sitting on my shelf. Set up for battery power only, some of the resistors are 1 watt(not required) and the crappiest (paper and glue?) perf board. But it works well, and has a chicken head knob from my grandpa's old parts stash. I found a good diagram for the switch, the input is grounded when the boost is switched out.

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whoop-whoopie! nice work ,very good presentation! yes sir-re-bob do it again with tape tempo and a reverse switch button.

 

[jeff_e]

Nice work. How are you liking the circuit?

Thanks. It's cool to get that overdrive sound earlier. It only starts to amplify above 5 on the gain pot, maybe because the pot is the wrong value.. I hooked up my USB scope and it puts out about 6 volts peak to peak before clipping, which seems to be plenty

whoop-whoopie! nice work ,very good presentation! yes sir-re-bob do it again with tape tempo and a reverse switch button.

Thanks, I'll definitely build another, I bought a 5 pack of stomp switches.

 

[ping-ping-clicka]

Thanks. It's cool to get that overdrive sound earlier. It only starts to amplify above 5 on the gain pot, maybe because the pot is the wrong value.. I hooked up my USB scope and it puts out about 6 volts peak to peak before clipping, which seems to be plenty



Thanks, I'll definitely build another, I bought a 5 pack of stomp switches.

 

[ping-ping-clicka]

further and further

 

[Kungpow!]

Good job

But... what does the toggle do?

 

[jeff_e]

Good job

But... what does the toggle do?

Thanks. Just a power switch

 

[zippofan]

The cool thing about that circuit is you can fit it into a tiny enclosure too, check out Delyk PCB's for a 1590LB version. I used a BS170:




MOD Kits makes the Piledriver which is a point to point version of the SHO:

 

[jeff_e]

The cool thing about that circuit is you can fit it into a tiny enclosure too, check out Delyk PCB's for a 1590LB version. I used a BS170:

MOD Kits makes the Piledriver which is a point to point version of the SHO:

Oh yeah, that is teeny. He's got quite a selection of pcb's.

Did you have to try different resistors to get the bias voltage correct? Mine has the most symmetric gain with 6.5v at point 'A', which is out of the suggested range (4.5 to 5.5). I don't know enough about mosfets to know if this is a problem. I think I ended up with 100k and 72k -ish for R1 and R2.

 

[zippofan]

Oh yeah, that is teeny. He's got quite a selection of pcb's.

Did you have to try different resistors to get the bias voltage correct? Mine has the most symmetric gain with 6.5v at point 'A', which is out of the suggested range (4.5 to 5.5). I don't know enough about mosfets to know if this is a problem. I think I ended up with 100k and 72k -ish for R1 and R2.

I just used the schematic values for the AMZ circuit, which is pretty much the same as the SHO in the MOD Kit pedal. I don't use enough MOSFETs to say, I know JFETs need the right bias, which can be a pain when trying different devices.
The Delyk PCB's are a fun challenge, but too nerve wracking when drilling for me to make any more. I'll be sticking to 1590B and bigger in the future

 

[jeff_e]

I just used the schematic values for the AMZ circuit, which is pretty much the same as the SHO in the MOD Kit pedal. I don't use enough MOSFETs to say, I know JFETs need the right bias, which can be a pain when trying different devices.
The Delyk PCB's are a fun challenge, but too nerve wracking when drilling for me to make any more. I'll be sticking to 1590B and bigger in the future

I'm going to add a 1590b to my next digikey order..
I think I'll try an opamp boost with switchable distortion diodes