The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Switch PCBs have arrived.
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- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
First prototype is built. No labels yet... this one is to make sure everything fits as designed and to figure out the drilling pattern.
All good. Sounds exactly like the bread-board prototype. It is a "different" type of OD - I don't think you will have an overdrive quite like this one...
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All good. Sounds exactly like the bread-board prototype. It is a "different" type of OD - I don't think you will have an overdrive quite like this one...
. .
- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Here is an electrical engineering design trick... Sometimes a high-gain output signal wire must be run near the input wire - the wires from the main PCB to the switch PCB do this. The input and output both have to be on the switch PCB to enable true-bypass.
If those wires run too close together there can be cross-talk (inductive/capacitive coupling) that will cause the circuit to oscillate.
So, how I always manage this is to use ribbon cable, with the input wire sandwiched between the ground wire (needed for the LED) and the +9V wire (also needed for the LED). This effectively puts a shield around the input wire and this stops any potential oscillations.
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If those wires run too close together there can be cross-talk (inductive/capacitive coupling) that will cause the circuit to oscillate.
So, how I always manage this is to use ribbon cable, with the input wire sandwiched between the ground wire (needed for the LED) and the +9V wire (also needed for the LED). This effectively puts a shield around the input wire and this stops any potential oscillations.
. .
- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
A tiny production line...
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
that 3.2 second clip sounds pretty fulsome and grunty - i'd be pretty pleased with that. was that with zero clean?
Jerem, Jeremy on BAF and SBZ
- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
YepLuke Drifter wrote: ↑Mon May 03, 2021 2:49 pmthat 3.2 second clip sounds pretty fulsome and grunty - i'd be pretty pleased with that. was that with zero clean?
There is one left in this batch if you would like one?
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
yes please
Jerem, Jeremy on BAF and SBZ
- laurie
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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Switches are mounted on the switch PCBs and connected to the main PCB with ribbon cable.
Next step is drilling the boxes.
This is the process:
1) Mark and punch the drill sites.
2) Drill (carefully!). The 0.5" hole for the footswitch is done with a step-drill. Drilling with a 0.5" drill bit is possible, but the large drill-bit can "wander", the step-drill does not.
3) Sand with 600 grit sandpaper.
4) Apply front label.
5) Spray (carefully!) the entire box and lid with satin clear-coat to "fix" the label and give consistent finish.
6) Allow to dry for at least one week so the clear-coat hardens before final assembly.
7) Final assembly and testing.
Next step is drilling the boxes.
This is the process:
1) Mark and punch the drill sites.
2) Drill (carefully!). The 0.5" hole for the footswitch is done with a step-drill. Drilling with a 0.5" drill bit is possible, but the large drill-bit can "wander", the step-drill does not.
3) Sand with 600 grit sandpaper.
4) Apply front label.
5) Spray (carefully!) the entire box and lid with satin clear-coat to "fix" the label and give consistent finish.
6) Allow to dry for at least one week so the clear-coat hardens before final assembly.
7) Final assembly and testing.