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Registered Member #1911
Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165
Hello Harry,
In my experience, MO diodes can be run for short periods (less than two minutes) at over 2A, though they tend to get 'quite warm'. The diodes are conservatively rated, obviously, and are usually able to take 15KV peak voltage (I have ran an OBIT rated 10KVRM 23mA through them successfully for extended periods).
It seems that MO diodes have a certain point where they will fail due to too much current; this point seems to be around 6A, even in short pulses. I have ran multiple MO diodes on a current-limited source rated at 36V at 20A, continuous. I ramped the voltage up slowly, and decreased the inductance that caused reactive current-limiting when the voltage was full. When I managed to get the current up to 6A, the poor diode didn't just release its smoke, it exploded in a manner that can only be likened to a miniature glass bottle containing dry ice and water, though the sound could be likened to a firecracker going off on one's shoulder.
I hope this clears things up and reminds you to wear safety glasses when working with these components.
Good luck with whatever project you are pursuing. =)
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Thanks for that, Christopher,
I 've found a UK supplier of MO diodes - which they characterize as "HVR1X7(HVR3H)" - for just £1.60 each (~US$ 2.60) which is very cheap by UK standards. Elsewhere, I found that these diodes are described as "12kV 550mA"
I'm building a C&W unit which is to be epoxy potted, so if any of the components are under-rated and fail, the whole thing will be a costly write-off.
It is a full-wave C&W powered by a 4kV-0-4kV transformer, so the question is whether two MO diodes in series, or three diodes in series, plus anti-surge resistors, are needed for each leg of the multiplier to give a very very low chance of failure even after many hours of continuous operation at low currents (5mA max)
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MO diode data help needed.
