Re: Another H1812 source

Joe Bachmann wrote:

> The HV diode can be tested with a DC power supply (even a wall adapter of
> at least 12 or 15 V output), series resistor (to limit current), and your
> multimeter. This will determine proper behavior, at least at low
> voltages.
> The following is the schematic of a simple HV diode tester:
> 240 ohms, 1 W
> + o-----------/\/\---------+------------o +
> |
> __|__ HV Good: 6 to 10 V
> 15 VDC _\_/_ diode Shorted: 0 to 2 V
> | Open or reversed: 15 V
> |
> - o------------------------+------------o -
> The voltage drop in the forward direction should be at least 6 V with
> a few
> mA of current but may be somewhat higher (8 V or more) with a few
> hundred mA.
> If your DMM or VOM has a resistance scale operated off a battery of at
> least
> 6 V, you may get a reading in one direction (but only one) without the
> need
> for an external power supply.

Yikes! Maximum RMS current is 4.6 mA and maximum voltage drop with 5 mA
current is speced at 85 volts for the H1812.

Your conditions would work for something like a microwave oven diode,
which can actually handle "a few hundred mA".

Let's try something else (if this doesn't look right highlight the
entire email and select "fixed width font"):

                                       ___
                    _ 33 Kohms / Ø \ NE-83 or NE-2
                ___| \ ___/\/\/\_____/_| |_\_________
                   | \ \ | | /
        115 volts | ) \___/ To diode
Wide prong --> ___| /______________________________
                   |_/
                                     

The "wide prong" of the plug should be the neutral (closest thing to
ground to come out of the wall outlet), but please only connect or
disconnect the diode with the power disconnected..

The resistor limits maximum current to protect both the neon bulb and
the diode. An NE-83 will be more sensitive, but any version of an NE-2
should work, especially if not kept totally in the dark.

A good diode will cause only one electrode in the bulb to light. If
both electrodes light the diode is either leaky or shorted. I'm not
thinking the bulb is going to light very bright while testing a HV
diode, but should still give an indication.

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Received on Sat Jul 20 22:07:33 2002