Input Voltage Handling for Projects--How do you figure it out?

[Myramyd]

Hello all,

On any of the projects here or in general, how do you tell what voltage the project can handle? (i.e. 9V, 12V, 18V)

Is this just determined by the specs of the ICs and/or Transistors used in the project? This is assuming most of the other parts (resistors, caps, etc.) can handle the voltage too. Or do you have to know what the voltage is doing at various points in the circuit where it meets those components? This is also assuming the project doesn't already have a charge pump in the circuit (Fatpants, etc.)

I'm sure it gets annoying with people always asking "Will XX handle 18V?" all the time. So I wanted to know how you calculate it for yourself.

Thanks!
J

[madbean]

Most transistors and ICs can handle more than 9v. Almost any overdrive or boost can be run at 12, 15 or 18v provided that the capacitors used are rated appropriately. It's a good idea to just use at least 25v rated caps all the time.

One thing to be aware of: for ICs, it's necessary to check the corresponding datasheet to see what voltage rating it has. The TCL2272, for example, has a 10v rating (although I've run them over that).

Some specialized components will not handle 18v. You would not want to plug 18v in a Pork Barrel chorus. But, 15v regulated would be okay, IIRC.

[stecykmi]

most transistors fail due to current rather than voltage. opamps are a little more fragile, but are still more sensitive to current than voltage. this isn't usually a problem when changing supply voltage.

it's usually the electrolytic caps and special purpose IC's, as well as the cmos IC's (CD4xxx is 15v and 74xxx is 9v I think).

[bigmufffuzzwizz]

so I could run my muffs at 12v, 15v, or even 18v?

[jkokura]

As long as your parts can handle the voltage you can. Will it sound good? I don't know.

Jacob

[bigmufffuzzwizz]

As long as your parts can handle the voltage you can. Will it sound good? I don't know.

Jacob

Yea of course that is the question. I'll have to get back to whether I can really hear a difference. If it means headroom I really don't mind my fuzz pedals nasty and noisy..

[stecykmi]

most people have better luck running fuzzes below normal supply voltage.

[bigmufffuzzwizz]

most people have better luck running fuzzes below normal supply voltage.

Right thus the bias knob. I've still yet to experiment with that.