I’m currently working on a design that involves a CD4066. This has a max power supply voltage of 20 Volts Vdd referenced to Vss. In a eurorack (+12 … -12 V) world, that range is not wide enough. I was thinking of lowering the modules input voltage by using a string of diodes. Maybe not a very elegant solution, but still… Anyone have a suggestion to do this in another way (I’m hooked on de 4066, so exchanging that is not an option I want to pursue right now).
typically the 4066 would be placed between GND and +12V, not -12V and +12V. You’ll then have to bias your signal to lie within that range. This makes more sense wrt to the control side of the circuit. Trigger signals are referenced to GND, not to -12V
In my experience when I connect the 4066 to GND the switches do not work well on negative input voltages (the ones I want to switch to an output). They seem to only switch the positive part of the signal as if they respond as diodes so to speak. They do respond well to negative input voltages if I give them a negative Vss. Am I missing something?
You are correct, they cannot switch voltages outside of their supply range. That’s why the signals are usually scaled and biased to fall within 0-12V. Then scaled back again afterwards. Two opamps and a handfull of resistors per channel should do the job.
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Ah, ok, thx! Well I’m going to try the diode way first and see how far this gets me before I add scaling.
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true and yes to that fact
I managed to get the voltages down using a few LEDs. I will post a schematic and some more details in the near future.
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Thx for the reference. I knew about the DG409D and other 30V types, but wanted to try it with the 4066 anyway.
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