RG's CD4053 Bypass Question - Bi Polar Supply

[MarshallPlexi]

I'm building RG's CD4053 bypass and I have a question. I'll be using a bi polar supply +/-9V. It's my understanding that in order to turn the switch on I have to supply a voltage to the control pins that is >2/3 of supply and to turn it off I need to supply <1/3 of supply.

So that would mean I need to send >3V to turn the device on and <-3V to turn it off. I'll be using a microprocessor to turn it ON/OFF so using 5V via a digital pin out will be no problem turning it on but the thing that is puzzling me is how to turn it off? I can't tie the control pin to a negative supply via a pull down resistor or I will kill the microprocessors digital pin.

Any ideas here? Would a logic shifter work?

[PRR]

> >2/3 of supply and to turn it off I need to supply <1/3 of supply.

No; the '4053 has a level shifter IN it. You will be fine.

[MarshallPlexi]

What do you know!!! You're right! I just got the chips and fired it up and it works with a 0V to 5V supply!!!

Thanks for the info!

[PRR]

I would say "read the datasheet!" but the current TI sheet does not make this obvious.

The secret clue is that '4053 takes *three* supply voltages. The audio can swing + and - of a center voltage. The logic goes by positive voltage _re_ that center voltage.

[MarshallPlexi]

I would say "read the datasheet!" but the current TI sheet does not make this obvious.

The secret clue is that '4053 takes *three* supply voltages. The audio can swing + and - of a center voltage. The logic goes by positive voltage _re_ that center voltage.

I PROMISE I read it!

I did find out something interesting today. Was using a power supply for the 5V logic signal and this power supply only had a 4.5V tap for some reason and it wouldn't flip over for anything! I got my better power supply out and slowly cranked it from 4.5 to 5V and right at 4.7V it flipped over!

Thanks so much for the kind reply.

[PRR]

> right at 4.7V it flipped over!

OK.

Run the '4053 on +5V, not +9V. You don't need 9V peaks in guitar-cord work. Obviously the internal trigger is "about half" the Positive supply. So at +9V it could be 3V or 6V, as you noted. Your 4.7V is just good luck. With 5V supply the nominal is 2.5V and the extremes about 1.5V-3.0V, within range for 5V or even 3.3V CPU control.