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Tap Tempo LFO module
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Tap Tempo LFO module
I wanted a Tap Tempo LFO module and decided to design one using the Molten Voltage/Pedal Sync MV-55 Tru-Foot LFO chip. I used the "B" version which powers up to the CV inputs rather than the default program. I built the Tap Tempo LFO into a 2U MOTM-style module.

It has both CV inputs and controls for Rate, Ratio, Duty, and Offset. I added level switches for +/-5 volt or 0 to +5 volt outputs. I added an external tap / clock input with an LED to indicate when the LFO is in sync with the external input. LEDs on all three outputs indicate the polarity (red/green for +/-5 volt and green/off for 0 to +5 volt operation).

I used a momentary toggle switch for the tap as I would rather press "down" rather than "into" a module.

The MV-55B does require about 85 mA of 3.3V so I added an option to run the module off of +/-15 volts or +5 and +/-15 volts. I hand wired the board since I was only building one. I have schematics, photos, and a lot of scope images on my Tap Tempo LFO page.

Molten Voltage/Pedal Sync was very quick to respond to all of my emails about the operation of this and their other parts. I have links to both sites on my page.

Very cool. Thanks for sharing.
Dang Dave, that's smooth like silk, like a glass of milk.
Looks great Dave!
Mine died on me eek!

DIY Euro + new cabinet = FUUUCCKKKK!!!

I'm going to build all over though, likely with all bells and whistles like yours'.
Very neat build!
Want to build. Chips are at Smallbear
Any chance Dave of doing a run of PCBs for this, either you or someone else? I'd be down for 1 for sure.
L-1 wrote:
Want to build. Chips are at Smallbear

SmallBear doesn't yet stock MV-55B which is the version Dave used that reads the pots on startup rather than loading program 1 (the chip was designed to also be programmable and MIDI controlled but I made a modified version at Dave's suggestion).

You can email me if you want to order MV-55B at

Great work Dave!

- William

Hey you on here!
Mr. looks like you're using TE headers and connectors. How are these compared to Molex KK MTAs?
keninverse wrote:
Mr. looks like you're using TE headers and connectors. How are these compared to Molex KK MTAs?

I am using the TE headers and connectors. I like them a bit better than the Molex. I'm not sure why exactly but the plastic seems to be a bit softer. I have the crimper for them but I always just press the wires in with a small screwdriver and then solder them for a reliable connection. I'm not a big fan of crimp connectors on wires.

I list the generic parts I use on my Parts page.

Nice alternative to the Tap Tempo LFO from Electric Druid.
Would be nice to have a finished PCB for this (gee, I'm lazy).
this looks great dave!
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