Re: 12V Zener

[K3yPr0gg3r]

I'm going to begin work on another discontinued build, the Ghost Note. It calls for a Zener, (1N4742), and while looking through the data sheet/info page on Mouser I noticed it pulls 12V. Just wondering if that's normal or if I need to search for a 9V 1N4742? Not trying to sound ignorant, just getting clairification.

Thanks

[BrianS]

A 1N4742 is a 12v diode.  A 1N4739 is a 9.1v diode. If the build doc says you need a 12v diode then thats what you need. And the question doesn't make you sound ignorant. I'm not real smart on how all this works but I am guessing the diode is boosting the current up to 12v to make the the board work like it is suppose to. 

[midwayfair]

Zener diodes in pedals are almost exclusively used as crude voltage regulators, but using the zener voltage as a ceiling on the voltage seen by certain components. They're commonly used to protect charge pumps but also to set reference voltages for FET when used as variable resistors in something like the phase 45.

Without a schematic I can't really help further, the only ghost note pedal I know is my small modification to the Afterlife, which doesn't use a zener.

EDIT: A diode does not "pull" any voltage. The word "pull" typically relates to current, though it's not exactly a technical term. Also, Brian's response is erroneous in suggesting that it boosts the current up to 12V. Current is measured in Amperes, not voltage; and the way to boost current involves trading -- whether through an active device or a transformer -- higher voltages with sometimes lower currents into lower voltages with higher currents. A buffer is a good example; the transformer in your amp goes the other way (120V with tons of A into 400+V with fewer A).

[Haberdasher]

the ghost note is a transistor fuzz (haunting mids from etcharz paradise) so they are probably just the clipping diodes that were used in the original or something.

[BrianS]

Thanks Jon for correcting my erroneous statement.  I knew someone would pop up and correct or confirm it.

[midwayfair]

the ghost note is a transistor fuzz (haunting mids from etcharz paradise) so they are probably just the clipping diodes that were used in the original or something.

Doh!

Yes, they're just clipping diodes.

Op, Zeners have two voltages (read the wikipedia article). In this configuration, they are just a pair of silicon diodes, because the paired diode will conduct long before the zener voltage is reached. You can use pretty much anything and it won't make much difference.

Jack Orman (muzique.com) has an article on how to actually use Zener diodes as clipping diodes, instead of as a more expensive 1n4148.

[madbean]

I didn't realize Ghost Note had already been used when I picked that name for the fuzz. My bad!

[K3yPr0gg3r]

Thank you all. Just doing some preparatory research before I place my order with Keefe in Oct. after the move.