Is a Zener Diode the same as a Diode

Hi

Ive been googling a bit, as I need a shunt diode for the attached circuit (ive added a zener where i think should it should go)

Im trying to clamp any spike that go above 12v

Is this right, and if so can anyone suggest a suitable zener for this purpose.

Its a 1Amp 5volt regulator if that makes a difference (probably not a 7805, due to its use in a car, but will be a regulator capable of handling load dump)

Thanks

No a zener isn't the same as a diode, if you really want to add one, try either a 15V or 18V 1.3W zener.

Problem is at 12V with a 1ohm current limiting resistor the zener will have to handle the current being shunted through it when more than 12V is present. At 14.4V (a car when running) you have to have a zener rated for 4.4V/1ohm or 4.4Amps that's a big zener. Besides in a car the spikes can be much higher... You could try a choke on the power feed instead...

A zener diode is a diode which will conduct in a controlled manner at its specified reverse breakdown voltage. A standard diode will breakdown (in an unpredictable fashion) at some voltage above its rated voltage. In the forward direction a zener looks like a regular diode.

Nigel Goodwin said:

No a zener isn't the same as a diode, if you really want to add one, try either a 15V or 18V 1.3W zener.

Click to expand...

Sorry nigel, my brain was working faster than my fingers when i typed the title, i meant to say the same as a 'shunt diode'

Bill, how would I use a choke for this circuit?

I need to get this stable as its the power feed my ECU, so I dont want it dying, frying, or any other nasty sounding nouns.

On a side not, how can i eliminate fuses from my Kit Car, I want to use some kind of circuit that detects a short, or possibly other problems on the powerline and disables the power to the load.

I want it to be a very modern car, with loads of modern toys.

Im thinking that it could mabey disconnect the the load, then check every so often to see if the problem is still there. If the problem is gone then restore power - if not wait a bit (until mabey 5 repeats, that make human interaction needed to reset)

is this doable - i dont mind if i need a uP in the circuit as there will be one there anyway.

Let me know if you think this should be a seperate thread - but they are bother power circuits.

it is better to use big condactivity coil for this (I think) to handle the spikes. I tried it ones and only this helped.