I've come across some 30v zeners in my shed (don't ask!). I need some 6.8v and wondered if I could use the ones Ihave in any way? I was thinking could they be used in series/parallel or anything or do those rules not apply to diodes?

Also, I've come across some IN5148 diodes which through Googling I believe are Varactor diodes! Can someone enlighten as to what they are and what I might be able to use them for.

Thanks

 

30V Zeners are 30V Zeners. Series will add the voltages. Parallel won't change anything.
1N5148: http://www.advancedsemiconductor.com/pdf/1n5148.pdf

Ken

 

Hello,

On this page of the EDUCYPEDIA you will also find links on the varactor diode:
http://www.educypedia.be/electronics/composemiconductordiode.htm

Varactor diodes are mainly used in voltage controled RF tuning circuits.
Sometimes they are also used in RF frequency multiplying circuits.

Bertus

 

You would have to put a 30V-6.8V=23.2V potential across the zener; this can be done by either creating a negative voltage source (-23.2V) or by floating your system ground 23.3V above a reference, then using the reference directly for the zener.

 

A varactor is a diode whose capacitance varies with voltage when it is back biased. It is a variable capacitor in other words, popular with autotune features in radios (among other things).

 

Many thanks people. As I have a 1000 of the diodes are they worth anything?

 

Not really worth anything. Do you know what power rating they are? DigiKey marks them up to 50c/ea for singles to ~2c/ea for 10k; 'suppose you could make $10.