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- Another use for Bob's ESR meter
- Phil Allison
August 29, 2011, 2:54 am
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** Hi all,
one of the most useful gadgets a service tech can own is Bob Parker's famous
ESR meter. Not only will it check the ESR of nearly any electro * IN
CIRCUIT * - it also reads resistors from about 0.1 ohms up to 99 ohms.
It will not generally matter if the particular resistor has an inductor ( ie
in a speaker crossover network ) or transformer winding in parallel - as
the test signal is a 100 kHz pulse wave.
Bob's meter will also check the ESR of cells and batteries, from the tiniest
lithium button cells up to NiCd and NiMH packs. Along with a simple voltage
test, it tells you a lot about the condition and state of charge of such
One more use is when servicing SMPS - often a MOSFET or high speed diode
will have a switching transformer winding in parallel making it test *dead
short* with an ohm meter.
Instead cutting leads to isolate the part so you can test it, just use Bob's
You will soon see if it really is shorted or not.
Re: Another use for Bob's ESR meter
** See schem of Mk 2 version:
In theory - up to 50 volts DC, providing C6 is rated for that.
In practice - any DC voltage you like IF you use an electro cap of about
100uF to isolate DC to the meter.
Zero the ESR meter with the electro in series.
Charge the electro across the DC voltage source.
Connect the electro and ESR meter across the DC source in series.
Don't let the voltage source or the electro BITE you !!