I would like to use CV Pal with my Roland SH-09 wich has a gate input that works at +7.5 Volt.
In the manual there is a point about that:
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.
Could you please help me doing this mod?
How do you plan to get the extra voltage?
doepfer has a simple non-audio amplifier (A-183-3), why not simply use this? Or build something equivalent. In either case, you would need a small extra power supply, the CVpal is powerd by USB.
Maybe better to mod the SH-09 with an adjustable gate amplifier, then you could use it with eurogear other than the CVpal also?
Sorry guys but if in the CVPAL manual it’s stated that it’s possible to use a CD4504 to have a higher voltage output i would like to know how to made this mod. Otherwise why it’s been written on it?
The CD4504 is a voltage level translation chip. It needs to be powered by a voltage corresponding to the required output voltage (there’s no magic, we can’t just make higher voltages out of nothing…). So if you want your output to be, for example 0V (low) and 15V (high), you need to power the chip with 15V.
Hence my question: where do you plan to get the +15V from?
Hence morcego’s suggestion to build the mod inside the SH-09 so that you could use its internal +15V supply.
Will a DC-DC step up converter like this work?
Yes, that would be a good solution if you want to keep everything USB powered. 12V output would cross the 7.5V threshold of the SH-09.
Ok, got it. I will do with the DC-DC converter
No, the DC-DC converter don’t work. It seems that the current is too low to drive it. Any other ideas?
Assuming the gate output is 0.05 mA, the DC-DC converter isn’t able to work and just output 3V.
I’m trying to find a solution without having to mod the SH 09. Any advice?
Wow, what you have done is really crazy! This is not how a DC-DC converter should be used - this is not a part for shifting up signals. It needs to be powered on continuously from a strong power rail ; not by a weak digital signal that goes on and off.
First of all, check that you have not destroyed the ATTiny. The DC-DC converter is quite a heavy load!
When I told you this part would work, it was for the following arrangement:
+5V USB supply from CVpal to DC-DC converter.
+15V from DC-DC converter and +5V from CVpal to level shifting IC.
+5V gate to input level shifting IC.
Probably yes, it’s crazy, that’s why i’ve asked for some help before doing it.
So i neel a level shifting IC and wire it as described?
Yes. And the power for the level shifting IC comes from the DC-DC converter, which gets a continuous supply of current from the CVpal’s +5V rail.
i have the same need.
i think, it can work with a simple level shifter like that :
of course i need an external voltage. But its small enough to be fited in the synth i want to control. Will try…