Systech - Harmonic Energizer

[D-Day]

Just finished building one on a Madbean 'Karate Shop' PCB. Added a volume control and the suggested by Grizzlydude 1.5u output cap on a switch with the other option being stock. Fun build, nice sound. I built it for an owner of an original so here in a few I get to see how he thinks it stacks up. Can't do a side by side as the original unit is now busted but the owner is a dog eared engineer who used it for lots of rock sessions over the past 20 years.

[D-Day]

Works like a charm! My buddy says it doesn't sound quite exactly the same but it definitely does the same job and he's just tickled pink. We hooked it up to a red knob Fender Concert and I noodled on my SG while he twiddled knobs. This thing is fun and awesome by itself but get a fuzz or a distortion in front of it and let the games begin! Thanks to Joe, Grizzly, Madbean and anybody else that contributed to my ability to give this gift to one of my greatest friends ever.

[terrapin]

Almost a year on and PurplePeopleEater's pcb layout (and Joe's original gut shots) have long gone. Anyone still have them and care to repost them? Pretty please?

[JOHNO]

Systech harmonic energizer.png

[jreeves47]

Some guts

[Nocentelli]

Got this on the breadboard at the moment, sounds good. I used a 2N5457 for the input buffer which works fine, and didn't bother with any of the power related circuitry other than the 10k/10k/10uF volateg divider.

I've also got a switch that puts either one or two pairs of antiparallel 1N4148s across the output opamp's inverting input and output, which makes the higher gain settings a bit smoother: The single pair just clips a bit earlier than two pairs. I'll probably use this when I box it up.

I have one question for anyone who understands this circuit: I'd like to use my EV-5 expression pedal for the frequency pot. It's a 10k, and I'm not at all sure what I'm doing, so I just tried reducing the 20k resistor that leads to the freq control opamp by a factor of 5 to match the pot value decrease. However, I just get squeals (through headphones - ouch). I'll have a go at altering those two 10uF caps, but I'm not sure if they should go up or down in value. Any ideas?

[Mbas974]

Are you using RnFR (page 5) schematic ?

[Nocentelli]

Yep

[grizzlytone]

Got this on the breadboard at the moment, sounds good. I used a 2N5457 for the input buffer which works fine, and didn't bother with any of the power related circuitry other than the 10k/10k/10uF volateg divider.

I've also got a switch that puts either one or two pairs of antiparallel 1N4148s across the output opamp's inverting input and output, which makes the higher gain settings a bit smoother: The single pair just clips a bit earlier than two pairs. I'll probably use this when I box it up.

I have one question for anyone who understands this circuit: I'd like to use my EV-5 expression pedal for the frequency pot. It's a 10k, and I'm not at all sure what I'm doing, so I just tried reducing the 20k resistor that leads to the freq control opamp by a factor of 5 to match the pot value decrease. However, I just get squeals (through headphones - ouch). I'll have a go at altering those two 10uF caps, but I'm not sure if they should go up or down in value. Any ideas?

Try increasing those 10uF caps with a factor of 5 (47uF), it might just work...

/MB

[aishabag23]

Here's a PCB layout for the Harmonic Energizer. You can board mount the pots or run wires, whichever. The PCB size is 3 inches x 1 3/4 inches, so it will easily fit in a Hammond 1590BB sized enclosure. I used a TL074 (as in Grizz' vero layout) instead of using 2 TL022 op amps. It just keeps things neater and the sound difference should be marginal at most. It should be correct (Eagle checks connections), but if you see any errors, please let me know.

I forgot to show the board connections on the bottom of the layout. The layout attached below has them marked.

Greetings,
Any chance you could link me to this? I can't seem to open the attachment (says it no longer exists).

Thank you!
Aisha

[roseblood11]

Does anybody know, how the additional switches in this version work? Would be great to include them.
https://youtu.be/lhNFPsbv2Lk

[Lani]

Thought I would add my layout here as well... Not verified yet but will build it in the next couple of days and let folks know.

[cniers13]

Lani, have you gotten it to work? I'm curious because I like the idea of adding a volume knob, instead of just the three knobs.