[Radio1950]

Here's my Meter Checker made last year to give me confidence, if I get an unusual measurement.

Made around an AD584 Voltage Reference and Dale 0.1% resistors, all sourced from Mouser, and one extrapolated accuracy resistor.
Used with a 20 volt 5 amp DC supply input, or lower current requirement if the 1.0 amp range is not needed.

It gives-

2.5, 5.0, 10.0 volts
1.0A, 0.1A, 0.01A, 1mA, 50uA, provision for custom, current into 0.0 ohms with 10.0 volts selected. It is proportionately lower if 5.0 or 2.5 volts is selected.
200K, 10K, 1K, 100R, 10R, provision for custom, ohms.

If used to check meters on current scale, you have to allow for meter resistance, and make a mathematical estimate of error.
But it will give a very close result.

Designed for 1.0 % checks, and I probably get 2.0% results or better, which is fine for me. It is only a checker, not a calibrator.

The AD584 has a double tiered darlington type boost circuit to give the 1.0 amp output at 10.0 volts, and all fed from a current boosted 7812 regulated 12 volts. It is good to about 1.5 amp at 10 volts before any noticeable voltage sag. I wanted a simple circuit without feedback current control.

Now, back to my reading about Wurzburg.
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