Hammond organ foot pedal controller conversion

[kdmr]

Stumbled upon a set of bass pedals from an old hammond in the junk pile. I've had my eye out for a long while for a set to make into a v/oct controller. I searched around for a bit and couldn't find a whole lot by way of other folks doing the conversion so I figured I'd post a build doc as I work on it. Stay tuned if that's your thing.

[Minimoog56]

Cool. I had a BV organ with a complete set of pedals, bench and Leslie251. Organ is gone but those pedals were dangerous. The metal contact strips were sharp. Gotta watch out. Also very heavy and bulky. Be careful.

[kdmr]

Cool. I had a BV organ with a complete set of pedals, bench and Leslie251. Organ is gone but those pedals were dangerous. The metal contact strips were sharp. Gotta watch out. Also very heavy and bulky. Be careful.

I've already gone through and cleaned and repaired some of the mechanicals. Definitely not something I'd want to do under my normal soldering conditions (full of beers). I'll be posting some pictures and tips for that in a bit.

[kdmr]

This is the unit I snagged. Luckily most of the mechanical bits were working as they should.

[kdmr]

First repair. There is a small plastic strip that throws each switch. One of these was snapped at the top, preventing the switch contacts from shorting. Normal operation is illustrated in the pictures(C= closed, O= open). The plastic strip is situated between the pedal assembly and the switch contact, so that when the pedal is pressed the strip travels upward and creates the closed state.

[kdmr]

The strip is about 2 inches long, give or take (couldn't get a proper measurement since it was snapped), 4 mm wide and about 1 mm thick. I tried a few really bad mends (one pictured) and the realized that I had some decently stiff plastic stock in the form of LP dividers filed into my record collection. These are not the exact ones I have but should work: https://www.bagsunlimited.com/product/2 ... ne-plastic
This alternative seems to work great. I did have to kind of ballpark the length but around 2 inches did the trick and the material is WAY less brittle than whatever Hammond was using. I may end up replacing all of them as a preventative.

[KSS]

Looks like the light blue O and C labels are backwards? The triple contact fingers on the O photo are contacting the leaf below while in the C pic they're clearly bent away from it?

[Slowpoke101]

You may find the following article of interest;

https://www.instructables.com/Arduino-MIDI-Bass-Pedals

The author used a very similar Hammond pedal unit and described some of its mechanics quite well.

[JimY]

Do you only get single-action normally open contact, one per note on those things? If so, you might look at Moog Taurus schematics. I think they impose a high-frequency signal on the CV output that is detected to provide trigger/gate for the pitch CV S&H. The HF signal is easily filtered out of the CV.

[kdmr]

Looks like the light blue O and C labels are backwards? The triple contact fingers on the O photo are contacting the leaf below while in the C pic they're clearly bent away from it?

I think you're looking at the wrong piece

[kdmr]

Do you only get single-action normally open contact, one per note on those things? If so, you might look at Moog Taurus schematics. I think they impose a high-frequency signal on the CV output that is detected to provide trigger/gate for the pitch CV S&H. The HF signal is easily filtered out of the CV.

I'm using Ray's single buss controlled pcb. I've had one for years kicking around it different arrangements but the end goal was always to put it in a set of pedals

[KSS]

I think you're looking at the wrong piece

Am I? You do realize these are normally closed switches? The three tines to the u-shaped piece in the wafer stack are the contacts.

[kdmr]

I think you're looking at the wrong piece

Am I? You do realize these are normally closed switches? The three tines to the u-shaped piece in the wafer stack are the contacts.

Yes, they are NC and yes I mislabelled them but I WON'T APOLOGIZE

[Grumble]

I to got an old organ with foot pedal and I just removed all the original switches that were allmost gone and instead I bought micro switches and used these on the pedal.
Here my brother using this foot pedal on Protools.

[kdmr]

Got her working last night. Ended up opting for a set of DG411 to deal with the NC switches. I need to redesign the board...left pulldown resistors off the first version mostly because I am an idiot so I have an extra stripboard shoved in to accommodate. Will post some more pictures of the switch busses and stripboard layout once I get a reasonably clean layout confirmed.