Midimuso cv-12 Pitch bend problem

Are pins 13 and 14 of U5 joined together?

You mean bridged with soldering?

I mean they should be joined on the PCB, 13 and 14 are joined to form a voltage follower, if they are not connected then I don’t know what the results will be, just meter the pins on the chip when its in the socket and see if they are shorted together 0 ohms.

Yes, they are indeed , 0 ohms on the multimeter

Then I’m at a bit of a loss, next thing up the chain is the PIC chip itself. I guess unless you have a scope then looking at the PWM output is not easy.

Hi Craigyb, you were right!!! one of my LM324N is defective, new chips arrive monday…

Have a good day

Thanks for your help



Glad to hear it, I couldn’t really get my head around the fault other than being the lm324 or possibly the level converter. I built a similar design as a test shortly afterwards with 28 channels and it works perfectly with 4504 and lm324.

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I really appreciate all the help

Have a great day Craigyb ( Greg is my brother :rofl: )

See you


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the level converter is the 4504? Right?

Correct, converts 5v to 10.6v that allows headroom for 0-10v PWM to send to the RC filter and then to the follower input of the lm324.

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Ok thanks! I’ll wait for the new chips and I’ll come back with the results…

Kind regards


WOW! 28? that is quite a big number of channels indeed!!! :star_struck:

Well it is 8 channel polyphonic, so that’s 8 pitch CV and 8 velocity CV channels, plus 4 dedicated to pitch bend, modulation, aftertouch and breath control. Then there are 8 gate outputs, the polyphony can be reduced and if you do that each note frees up two outputs and a gate output to be used for other CV controls and drum triggers etc. it’s still in development, but I’m happy so far.

Well, I just love what I just heard so far. Quite an impressive beast. Keep on the good work​:wink::+1: