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Old March 31st 04, 06:31 PM
Tom Bruhns
 
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Scott wrote in message ...
I have a circuit that puts out 0 - 5 volts to drive a meter. However the
meter I want to use accepts 0 - 10 volts. The response is linear, so if
I could just double the voltage, I could make this work. Any simple
devices or circuit that can accomplish this? Thanks, Scott.


An easy way to double the voltage is to use an op amp circuit. If you
use an op amp with rail-to-rail input and output, or at least
including the negative rail, you can get by with a single power
supply. You'd just feed power to the op amp (e.g., 12V or 15V to the
+power pin, and ground/common to the -power pin), connect the input
signal to the (+) op amp input, and connect two equal-value resistors
(say 100kohms each), one from ground/common to the (-) input, and one
from (-) input to output. Meter to output terminal. To find an
appropriate op amp, try searches on web sites like National
Semiconductor, Maxim, Analog Devices, Texas Instruments, Linear
Technology, ... You get the picture...a awful lot of companies make
such parts. Just pick one that suits your needs rail-to-rail
operation and power supply voltage...likely everything else will be
OK...stay with low speed ones for low power and lack of problems with
circuit layout.

But why not make it even simpler? Take the meter apart, and locate
the series resistor. Replace it with a resistor of half the value.
Then you'll have a 0-5V meter, and no power-draining op amp circuit
will be required.

Cheers,
Tom