CVpal and Moog Source

Hi there,

I successfully built a CVpal, and now I’d like to use it with my vintage Moog Source. So I bought a Doepfer Gate->S-Trigger converter cable and connected the Moog’s S-Trigger input to the CVpal’s gate output, and of course also the CV (the CVpal is connected to an iPod Touch) - but the Moog doesn’t get triggered properly. It mostly plays a constant tone and reacts to the trigger/gate messages only very rarely.
Does anybody have an explanation for this?
And maybe any idea how to change the Gate outputs of the CVpal to S-Trigger?
Thanks in advance

"The CV output is in the 0 … 4V range – so a tessitura of 4 octaves is covered. The CVpal does not support V/Hz conversion; only V/Oct.
The Gate output uses V-trig, has a 5V high level, and a direct polarity (note on = 5V, note off = 0V). Most Eurorack modules use a trigger level below 2.5V and can thus be triggered by the CVpal. If a module or synth requires a higher level, a level conversion circuit such as the CD4504 can be used. Polarity inversion can be implement with a CD4049 or with a software hack. S-trig conversion can be implement with a few parts."
Straight form the manual.

Can’t tell you much else, Since I don’t own any moog synths :confused:
(Check what trigger voltage the moog needs?)

Maybe you’d need an extra inverter stage before the S-Trigger converter?

cannot find out anything about the trigger voltages. I’ve posted in another forum, too, maybe somebody there has an idea.

S-Trigger means that the quantity to be considered is not voltage but whether the circuit is opened or not. What would have to be known is whether open circuit = gate on / closed circuit = gate off ; or the opposite…

all I can say is that I use a Doepfer converter cable which is described here:
http://www.doepfer.de/faq/gen_faq.htm#S-Trig

Did you buy the cable from Doepfer or did you build it yourself?

Do you have a multimeter to check that there’s continuity between the two terminals of the cable when a note is held on the CVpal (ie, when the signal on the gate output is +5V).

I bought it from Doepfer. I will check with the Multimeter and let you know

I didn’t check with the multimeter yet, but I have now tried the Moog with a different MIDI-CV-Interface: the gate works perfectly with the Doepfer cable - but the CV doesn’t… But this could be due to the fact that the Source’s CV input needs a stereo jack with “Tip = not connected / Ring = CV input signal” and I don’t have an appropriate cable at the moment. I will try to get one eventually.
Still it’s strange that I don’t get the Moog triggered with the CVpal…
Anyway - thanks for all your help!