[SOLVED] Voltage Level Range Converter Shifter

[erikl]

I had thought about using the inhibit on the 4051 and tying that to the same switch that I am using for the 4066, so when I switch the 4066 for external CV in I am disabling the 4051.

Sure, this is fine, if you don't need the other 3 CV Channels [234] at the same time as the external CV.

BTW, I forgot to mention: For the 4066 pull down (R24) a 100kΩ resistor is sufficient.

Cheers, erikl

 

[apprenticemart2]

Hi erikl,
I won't need the other CV channels as I will be trying to replace them all with external signals, so the voltage shifter and 4066 switch circuit will be x4.
I couldn't decide between 10K and 100K. 100K sounds like it is the correct option but I wasn't sure.

Thanks for your advice
Martin

 

[apprenticemart2]

I'm updating this in case anyone else wants to mod their SX-400.

For some reason I got a faint high pitched sound in the background when I tried to use the inhibit on the 4051 so I decided not to use that.

I had to send the pull-down resistor for the 4066 to -5v. It wasn't working going to GND.

I left off the 100 ohm input resistors that the original single CV in had. The 4066 on resistance and the wires etc add up to around 40-60ohm anyway.

The whole system seems to work fine. I added a switch and LED to disable the internal circuits.

 

[erikl]

I had to send the pull-down resistor for the 4066 to -5v. It wasn't working going to GND.

Yes, that's absolutely correct.

Thank you for your feedback!

 

[apprenticemart2]

Thanks to everyone who helped. I couldn't have done this without you.

I will post the schematic for the Gate signals that trigger the playing of a note as well, when I get it finished.

 

[apprenticemart2]

Gate In schematic. Remember, you will need to insert dummy jacks into the original CV/Gate socket to disable the internal circuits.