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Subject: Re: LED Amp meter
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 16 Sep 2002 04:39:58 GMT
NNTP-Posting-Date: Mon, 16 Sep 2002 06:39:58 MET DST
"Mike Poulton" schrieb im Newsbeitrag
> On 15 Sep 2002, The.Central.Scrutinizer.firstname.lastname@example.org said:
> > In article ,
> > email@example.com wrote:
> >>Does anyone know of a circuit to build a DC Amp meter? 0-5 amps at a
> >>max of 30 VDC. I could use any DC amperage really, I could just shunt
> >>it. I would like to get .1 amp resolution on it tho. Acuracy isn't
> >>critical, it is just for my bench supply.
> > get a first year electronics book and look up ohm's law.
> I think he's looking specifically for an led display meter circuit, not
> just any meter. He seems to understand the ideas of measuring voltage
> across a shunt. What he deosn't say is what kind of LED display he
> wants to use. Without more information, there isn't much to say.
get a shunt with 100mV at 10A (10mOhm) and place it between the pass
transistor and the voltage sensing resistor. Then buy a LED-meter and use a
separate isolated power supply to power it.
If you want to use the power supply to power it, get a Maxim high side
current sensor, feed the output current into a resistor to gnd and measure
the voltage across that resistor. derive the +5V or whatever the meter needs
from the unregulated DC, be careful and use a high input voltage regulator
or some zener to keep input voltage within specs. You also need a meter with
voltage sensing capability to gnd (more expensive).
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