EHX - Clockworks EH5385  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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JuliaDee
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my favorite amplifier: 2N5088
Completed builds: Invented and designed: EH-8000 Guitar Synth, E-H Space Drum, Super Space Drum, Crash Pad, Sequencer Drum, Clockworks. Designed: Zildjian Gen-16 Acoustic-Electric Cymbal System.
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Post by JuliaDee »

Glad you got it working! EBC is the standard pinout, as shown at the left side of your attachment.

The clock needs to be buffered for both sourcing and sinking of current because it's the _falling_ edge that triggers the reset comparator through the 10NF cap. You can probably use a complementary buffer on the 40106, although you'd have diode drops with emitter follower buffers.

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ruebezahl
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Post by ruebezahl »

Ah, thanks, that makes sense!

Yeah, the left side is right, but the numbering is not identical with the right side :D So i got confused. Anyway, it is working now.

I might do another PCB layout, since the one by the other user is eagle format and i use KiCAD. If i happen to finish it i will also share it here, i am actually still trying to add some functions while i am at it ;) I wonder if anyone ever made this one?

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photon
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Post by photon »

I was planning on making a board from the original trace art. I’ve been cleaning it up and making a component side view for use as a part placement guide. However, the posted art seems to deviate from the schematic in a few places. For instance, the 4 NPN transistors (that I presume are driving the LEDs) are missing, as are the 4 100K trimmers. There are other differences, as well.
Did anyone else notice this?

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JuliaDee
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my favorite amplifier: 2N5088
Completed builds: Invented and designed: EH-8000 Guitar Synth, E-H Space Drum, Super Space Drum, Crash Pad, Sequencer Drum, Clockworks. Designed: Zildjian Gen-16 Acoustic-Electric Cymbal System.
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Post by JuliaDee »

I think you're right - I don't see those NPNs or the trimpots either. No idea, maybe the layout I posted was before the final version. The NPNs are required not just for driving the LEDs, but basically for driving anything from the LM339, since its output is open-collector. Best would be to start over with a fresh 4-layer layout in KiCAD. Don't know if you can get those slide pots anymore anyway.

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photon
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Post by photon »

Wow, that was fast!
I was planning on updating with the foot print for modern slide pots once I verified the layout. If I continue, I’ll probably have to manually lay it out, as I don’t have KiCAD or Eagle.
Thanks for the reply. I appreciate it.

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JuliaDee
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Joined: 18 Feb 2011, 17:51
my favorite amplifier: 2N5088
Completed builds: Invented and designed: EH-8000 Guitar Synth, E-H Space Drum, Super Space Drum, Crash Pad, Sequencer Drum, Clockworks. Designed: Zildjian Gen-16 Acoustic-Electric Cymbal System.
Location: Connecticut
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Post by JuliaDee »

Well, KiCAD is free, good, and pretty easy to use (or at least v5 was, I think they're on 6 or 7 now). Eagle not so much, imo :) Good luck!

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photon
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Post by photon »

What's the recommended replacement for the 2N6111 & 2N6290 Bi-polar transistors?
Edit….Never mind I just grabbed some NOS. :D

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