Zener Diodes - No !

[sj-bradley]

I have seen several posts on here mentioning zener diodes when you really mean ordinary rectifying diodes.

 

To be clear, I have attached a diagram on what a zener diode does.

 

This zener is rated at 6.2 volts and as you can see the test point is at 6.4 volts from the 9 volt battery supply. But notice that there IS a current flowing at 26 mA.

 

An ordinary diode will NOT allow current to flow in the reverse direction and you are looking for the 1n4000 1 amp series or the 1n5400 3 amp version which only allows current to flo in one direction.

 

You want diodes that are "power rectifiers" and NOT zeners or "signal" or any other type (there are many others, all of which do different things.

 

I hope that helps future builders. AVOID Zener diodes, they are usually NOT what you are looking for.

 

Simon.

Edited May 11, 2015 by Simon B

[Shaft]

My head hurts!

[richyb66]

I thought zener diode was a song by Olivia Newton John and ELO

[Guest Ian & Carole]

In a language we all understand.............

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

"£%%^&& y^&*() ggge$%^&&(_ Z%^^**&__+ v"£!$$^^(( B!")(*&++) H&^%$£*((

 

My head hurts also !!!!

[sj-bradley]

Crumbs.

 

And them's the SIMPLE circuits ...

 

I only wanted to point out that you cannot use Zener diodes instead of ordinary ones ...

 

Simon.

 

Perhaps this will be simpler ... ?

 

[theduck]

Why didnt you say that in the first place? That's much simpler!

[fry61]

You'll be telling us next that current flow is from negative to positive, Simon.

[Guest 2b cruising]

No Norman Please don't.

He was only winding you up so you could baffle us even mooooooooooore.

#+%=bed time for me.

[Snapperpaul]

The Megajolt uses Zener diodes to feed a tachometer signal from a coil pack to a tachometer designed for a distributor type coil

[Grim]

They are NOT the diodes you are looking for.

 

Hey, i thought you were Yoda?

[Guest chris brown]

You'll be telling us next that current flow is from negative to positive, Simon.

No it is holes that flow from positive to negative.

[brumster]

"...but if your diode walked in here, and started prancing about letting current flow in both directions? I'd say....

OI! ZENER! NOOOOO!"

[Guest peter2b2002]

I thought diodes only allowed current to flow one way but a zenner block all one way but let a little flow the other way or am I thinking that's where my money goes to swmbo

peter2b

[sj-bradley]

Correct about diodes letting current flow one way.

 

Zener diodes are designed to breakdown at a certain voltage and start allowing current to flow backwards.

This means that (for car applications) when you have a charging battery from 12.9 to 14 volts say, if a 12 volt zener were used, then the voltage across the zener would remain more or less constant at the 12 volts specified and it allows just enough reverse current to keep this 12 volts a constant figure.

 

It is a cheap voltage regulator, but it has its own drawbacks that I shall not go into here.

 

Let's just say it's a leaky diode that breaks down at a low voltage compared to the diodes you ARE looking for which have break down voltages in the hundreds of volts - even up to 1000 volts.

 

With the correct diodes, the force is strong in them ...

 

Simon.

[Snapperpaul]

Talk me through this

 

I know it works as I had it my hood but want to understand how