[Prev][Next][Index][Thread]
High Voltage Diodes
----------
From: Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
Sent: Sunday, March 01, 1998 9:56 PM
To: Tesla List
Subject: Re: High Voltage Diodes
>
> ----------
> From: RODERICK MAXWELL [SMTP:tank-at-magnolia-dot-net]
> Sent: Saturday, February 28, 1998 12:15 PM
> To: tesla-at-pupman-dot-com
> Subject: High Voltage Diodes
>
> I have four 15Kv-at-750ma microwave oven diodes that I plan on using in a
> Dc supply for my new tesla coil. When I test them with my ohm meter they
> all read infinite resistance even when I reverse the leads. Is this a
> property of high voltage rectifier diodes???
Internally, those diodes have a number of lower voltage diodes in series
(it varies a lot how many, depending on mfr). Say there are 15 diodes, each
at 1 kV each (for example only, typically they would have a bit of margin).
The forward drop of each diode is around 0.6 Volts, so 15 would have a
total forward drop of 9 Volts. Your DVM probably uses a lot less to measure
the resistance (200 mV or so, unless you are on the diode checking
setting).
Try hooking them up with a 24 V dc power supply and a 2.2 K resistor in
series (to limit the current to around 5-10 mA). Then measure the forward
voltage drop when forward biased. My microwave oven diodes measure a Vf of
around 14 volts. Reverse biased, they should read the full supply
voltage...
BTW, they give the Vf spec in the catalog for the diodes.