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Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Wed Apr 28, 2021 12:18 am
by laurie
Switch PCBs have arrived.
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- Switch_PCB.jpg (34.4 KiB) Viewed 5490 times
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- Switch_PCB2.jpg (16.77 KiB) Viewed 5490 times
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Sun May 02, 2021 2:27 am
by laurie
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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- 32OD_dry_fit1.jpg (50.74 KiB) Viewed 5458 times
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- 32OD_dry_fit2.jpg (14.05 KiB) Viewed 5458 times
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Sun May 02, 2021 2:55 am
by laurie
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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- 32OD ribbon1.jpg (86.48 KiB) Viewed 5455 times
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- 32OD ribbon2.jpg (12.81 KiB) Viewed 5455 times
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Sun May 02, 2021 7:18 am
by Pepe
laurie wrote: ↑Sun May 02, 2021 2:27 am
It is a "different" type of OD - I don't think you will have an overdrive quite like this one...
Very nice to hear!
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Mon May 03, 2021 12:03 pm
by laurie
A tiny production line...
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- 32OD_Production1.jpg (173.55 KiB) Viewed 5439 times
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Mon May 03, 2021 2:49 pm
by Luke Drifter
that 3.2 second clip sounds pretty fulsome and grunty - i'd be pretty pleased with that. was that with zero clean?
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Mon May 03, 2021 3:22 pm
by laurie
Luke Drifter wrote: ↑Mon May 03, 2021 2:49 pm
that 3.2 second clip sounds pretty fulsome and grunty - i'd be pretty pleased with that. was that with zero clean?
Yep
There is one left in this batch if you would like one?
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Tue May 04, 2021 8:57 am
by Luke Drifter
yes please
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Tue May 04, 2021 12:35 pm
by laurie
- 32OD_production2.jpg (147.87 KiB) Viewed 5403 times
Re: The 32 OD Pure Germanium Overdrive pedal - design and build in words and pictures
Posted: Thu May 06, 2021 2:04 am
by laurie
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.