Need help with zener diode

[SirEgno]

Hi all,
I'm building a preamp pedal based on sunn O))) beta bass.
My idea is to use different input voltage (9 or 18v), so I'm planning to use this schematic as "power section":


I tested the circuit without any chip, and with 18v input the DMM shows 17,8 volts.
Am I doing something wrong?

[cooder]

Where did you source the zener diode? I think I recently had some funky ones from Tayda... ordering those values form Mouser now.

[SirEgno]

I bought them from musikding.
Is there a way to test a zener diode?

[Scruffie]

CLR, a zener isn't a regulator.

[SirEgno]

I don't remember the source, but I read that the 5817 should act as a resistor.
in fact the DMM shows about 50 ohms. Is it not correct?

I've seen this schematic used in many project. That's why I omitted the CLR.

[cooder]

I don't remember the source, but I read that the 5817 should act as a resistor.
in fact the DMM shows about 50 ohms. Is it not correct?

I've seen this schematic used in many project. That's why I omitted the CLR.

It certainly has a bit of voltage drop that matches what you read with DMM.

[Scruffie]

They do act as a resistor... under the right conditions, the resistance will vary with voltage and current across it.

[SirEgno]

Got it. the zener is not the best solution, better a 7815 and "passa la paura".
BUT... I have only one 7815 and it doesn't work. It became hot and in output I measure 0.peanuts volts.