Diode in TS808

[samrsmiley]

I have a schematic from http://www.schematicheaven.com/effects/ggg_ibanez_ts-808_truebypass.pdf and am trying to build this pedal.  What is D5?  I think that's in the power section-making a bias voltage, or the 4.5v source, and guessing that diode filters AC?  Maybe not-I'm pretty new still.  What kind of diode does it need there?  I have 1N914s and LEDs, will those work?  Thanks for the help guys!

[Jimmy-H]

D5 is just a protection.
If you have a reversed powersupply, this diode will protect the circuit.
Once it has done his job, you have to replace it!

1N914 will do fine!

[cpm]

If you have a reversed powersupply, this diode will protect the circuit.
Once it has done his job, you have to replace it!

so it is supposed to eat all current from the reversed power so it doesnt get to the main circuit, right?

what happens if the power is much higher that the usual 9v? it would burn out and current will flow into the main circuit, i guess.
I've seen some circuits also include a low value resistance in series right from the main V+, which can act as a fuse. When it blows up there is no power anywhere in the circuit. Look at the RAT schematic as one of many examples.

[Jimmy-H]

so it is supposed to eat all current from the reversed power so it doesn't get to the main circuit, right?

Yep!

what happens if the power is much higher that the usual 9v? it would burn out and current will flow into the main circuit, i guess.
I've seen some circuits also include a low value resistance in series right from the main V+, which can act as a fuse. When it blows up there is no power anywhere in the circuit. Look at the RAT schematic as one of many examples.

The circuit can have much higher power (12 volt for instance)
It depends on the electrolyte capacitor's limit it can have.
The Chip can have approximately 18 volt.
So any higher and it will blow your chip.

And the resistor is probably a part of a filter.
You will probally find an electrolyte right behind it.

For higher protection, you could use a zener diode.

[cpm]

i once put by accident -24v into a RAT, the diode did its work but that resistor (47ohm) got burned.
I thought it was made that way on purpouse.