Products > Test Equipment
Multimeter Overclocking
beenai2018:
Hello
I have a "slow as paint drying, " extech ex430A especially on the low ohms range. It's terribly bad and rather unpleasant when a reading takes 6 seconds and the last digit still flickers.
The rest of the meter is not bad floor for my hobbyist purposes.
I would watch with envy as the Anengs would zip about and turn green with jealousy when flukes were fast and settled too in various reviews
I got a ex430A as a warranty replacement so decided to hack my old one. These meters have the 7721 chipset which are not great but they work. The Meters all have a 4 megahertz clock(maximum, apparently, lol) from the data sheet.
Since most multimeters are supposedly ratiometric , increasing the clock should just speed up the measurement(I thought). So went through my assorted junk box of crystals and I had 18, 16, 25, 3.57, 11.05 and 50 MHz.
My theory was any multiplier of four might be the best bet.Started out with the 16 and everything sped up. voltages, resistances were fine and got faster. Capacitances were multiplied by 4 and and currents were off on the amp range.
Since 16 was okay I tried the 25 and the meter still works on volts and resistances and it is zippity fast however currents have a weird issue where the value would lock on the correct value or be incorrect at random.
Some crystals cause a multiplier on currents. Mostly looked like a y=Kx but some looked like a y=Kx+b.
Bottom line was the voltages and resistance is always worked fine however currents had an issue where it was a simple multiplier or at higher frequencies it was randomly off.
Just to give it a shot I tried the 11:05 Crystal and that worked perfectly. Voltages currents and resistances work and match with my other unmodified meter. I tried to test the lowest current ranges by supplying a few microamps and it was spot on. The capacitance has a approximately 3X multiplier. Temperatures measurements match. I'm not sure why an oddball Crystal that is not a multiplier of four works best. But it does and the meter is significantly faster.
I will try a video when I get a chance, but yeah ,same feeling as pressing the turbo button ,lol.
Warning : Modifying testing equipment is dangerous. This can give false readings and a false sense of security. This can harm , maim or kill you.
LazyJack:
How about the power consumption of the meter? I assume that could increase significantly with the clock speed increase.
beenai2018:
Didn't measure the power consumption.Im running off rechargeable 9V which last for awhile.
Given that ,I would take the faster meter any day at the expense of power . Much better than waiting for the value to settle.
coromonadalix:
toss the mete away, i tried on some uni-t models, yes youll get inconsistent measurements on some ranges ... tried many xtal values ... even recalibrate them is no good
Fungus:
It will probably go horribly wrong if you just increase the clock speed. ADCs are designed around capacitances, etc.
Just get a faster meter and be done with it.
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