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Ian Stirling
 
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Default Turn Your Power Supply into an Ohmmeter - It's Free!

In sci.electronics.misc Watson A.Name - 'Watt Sun' wrote:
In article ,
mentioned...
In sci.electronics.misc Watson A.Name - 'Watt Sun' wrote:
I got tired of switching the leads of my DMM. Suddenly if dawned on
me that I can just set the power supply to 10.0V for exaample, and
read the current, and then divide the voltage by the current to find
the resistance. Like I put a resistance on the PS, it reads 10.0V and
the current is .018A, so 10 / .018 gives 555.6 ohms. Must be a 560
ohm resistor.

I turned my PS into an ohmmeter - FREE!

Hee-hee - Work smarter, not harder!

Of course, make sure the current stays low so the resistance doesn't
overheat. For low resistances use a volt or less.


This isn't especially usefull usually.
However, with low ohm resistors, it can be.

Given a constant current of an amp, the $5 meters mentioned elsewhere
can now measure with a resolution of .1mohm.


I bought a few of those $5 DMMs from Futurlec a few months ago,
actually I think they were about $6. 9V vattery included(!)


Very handy indeed.
The ones I bought were 3 pounds 99p, ($6us?) I have around 8.
Soon after buying one, I thought I'd discovered that they have an
overvoltage LED.
However, the smell of burning FR4 soon made me realise otherwise.

It's amazing how many multimeters you can use when you have them free.
I was just discharging a series string of Li-Ion batteries, to measure
capacities.
In the past I would have taken measurements every 5 minutes to ensure
none had approached 3V.

Why bother, just hook up 5 of them, and glance over every once in a while.,

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
Lord, grant me the serenity to accept that I cannot change, the
courage to change what I can, and the wisdom to hide the bodies
of those I had to kill because they ****ed me off. - Random