Chris Bacon wrote:
On 15/05/2021 01:02, Paul wrote:
Is it possible the diode is actually made of diodes in series ?
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CL01-12 Diode Microwave Oven High Voltage 12kV 350MA
12kV repetitive peak reverse
350mA average output forward
30A surge, 8.3msec, forward
Vf 12V max at 350mA --- about 12 diodes in series or so
at roughly 1V drop on each,
cannot be
checked on "diode" range of
multimeter
2 to 50ua reverse leakage
You would need to make up a little test circuit
to verify the forward characteristic.
No idea. It's a CL04-12 if that makes a difference. I don't know what a
test circuit would be.
To be applied only with the diode out of the circuit.
(+) band
+18V (two 9V battery) -------- R1 ------ diode ----+
|
GND -----------------------------------------------+
Itest = 18V - 12V / R1 = 6 / R1 [Very approximate equation]
R1 = 100K Itest = 60uA
R1 = 10K Itest = 600uA
R1 = 1K Itest = 6mA
V_across_diode + Plotting the diode
| X forward characteristic
|
| X
| X
+-------------------- Itest
Now, reverse the diode so it is reverse biased. No current should
flow. But we know that the diode does have some reverse leakage.
2uA * 100K = 0.2V , Vdiode = 17.8V, 0.2V across R1. The only
effect from changing R1, is to change the drop voltage value.
So across R1, we get the "reverse leakage" while a piddly 18V
is applied. When there is 12kV across the diode, that's when the
real leakage level is realized.
That's an example of building a test circuit, when your meter
is poorly suited to the task. The meter assumes on "diode" range,
that the diode is a single junction, with a 0.7 to 1.0V Vf value.
A TV repairman, spins in his swivel chair, reaches for the Tektronics
curve tracer, throws the diode on it, and traces the diode characteristic
to 100V or so applied voltage. Which would be acceptable for this
task. Curve tracers are good to that sort of test magnitude, somewhere
around 100-150V or so. And likely with fine controls, because if
you were curve tracing one of the mosfets with dual gates, the
ones that are "static sensitive", the gate on those blows out
at 40V, and you'd be very careful to adjust the sweep parameters.
In this little experiment, we're not pushing the diode to avalanche,
as that requires too much test voltage. And would blow out our multimeter :-)
We're manually tracing just a portion of the curve. The nine volt batteries
in the example, can't supply 350mA to "test at rated spec".
http://www.learningaboutelectronics....tics-curve.png
But we can at least see a little bit of "front to back" behavior,
with our higher-voltage power source for test. The meter doesn't
have 18V to apply to our device. I limited my experiment to 6mA,
so the batteries would last.
Paul