Moog Music Forum

Hello!!
Need one of these but im not able to find one for a resonable price in europe(sweden). So im looking for a little less pricey alternative.
would a Hosa gpp-419 work? or maybe somone knows how to make one yourself?

Magnus

How do you want to trigger/clock the MuRF? The simplest way would be to solder a TRS cable to 2*TS plugs or sockets, with the sleeve wired to both. You could also adapt your footswitch or a special cable to be wired on the ring terminal instead.

Another way is to buy a 1/4" stereo plug to 2* mono sockets adaptor, ensuring that the T and R positions are indeed separate.

I Would like to be able to trigger it step by step with a gate signal.

I noticed as well, that both tip and ring on the tap/step input is sending positive voltage (somewhere around 3,2v). is it supposed to do that?

It's been a while, but I'm pretty sure the MuRF uses an "S-trig" for the tap/step jack. This means it triggers on the falling edge of a clock or gate, or is done with a normally closed (push to open) footswitch.

If this behaviour is unwanted, you could also build in the infamous S-trig converter using a resistor and NPN (with an optional diode).

Oh! of course its a S-trigger, didnt realise they where still used.

Presumably you have a positive 0-> 5V gate, so if I'm getting this right, the MuRF would step 180 degrees out of phase or as the gate signal was released.

Here's the circuit to convert V gates into S trigs:

http://www.retrosynth.com/docs/trigger/ ... onvert.jpg

Should also work to run the signal through an inverter.

I might have the footswitch mode wrong though, best to check. What I remember from years ago, is that the step would occur when I released what I think was a normal footswitch that closed when pressed.