Convert 0 to 5 Volts DC to 0 to 10 volts
 

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.

Scott wrote:

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.

A different meter. Sorry, I couldn't resist.

If you have a 12V supply handy you could use an op-amp to amplify the
0-5V by 2. You'd need one op-amp, a bypass cap or two, and two
equal-value resistors. This is an easy circuit and should be in any
ARRL Handbook after 1970 or so. Even one of those "Engineers
Mini-Notebooks" from Rat-Shack should do, if there's one on op-amps.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Scott wrote:

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.

A different meter. Sorry, I couldn't resist.

If you have a 12V supply handy you could use an op-amp to amplify the
0-5V by 2. You'd need one op-amp, a bypass cap or two, and two
equal-value resistors. This is an easy circuit and should be in any
ARRL Handbook after 1970 or so. Even one of those "Engineers
Mini-Notebooks" from Rat-Shack should do, if there's one on op-amps.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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

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

Tom Bruhns ) writes:

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.

I started to post an answer like that, until I realized that he
didn't specify what kind of meter.

I'd even go further, to point out that while analog meters have
all kinds of scales, they may not even have a resistor built in.
They might just be a current meter and expect an external resistor
in order to read whatever is on the scale. This the more so
if it's just the movement, but obviously not the case if it's an
actual "voltmeter" with the movement in a box etc.

If it's just the meter movement, and does not actually have the
resistor inside, then one has to calculate the resistor value
using ohms law.

Michael VE2BVW

Tom Bruhns ) writes:

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.

I started to post an answer like that, until I realized that he
didn't specify what kind of meter.

I'd even go further, to point out that while analog meters have
all kinds of scales, they may not even have a resistor built in.
They might just be a current meter and expect an external resistor
in order to read whatever is on the scale. This the more so
if it's just the movement, but obviously not the case if it's an
actual "voltmeter" with the movement in a box etc.

If it's just the meter movement, and does not actually have the
resistor inside, then one has to calculate the resistor value
using ohms law.

Michael VE2BVW

Scott wrote:
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.

Open up the meter movement and locate the resistor that is in series
with the meter movement. Using Ohm's Law, calculate what the correct
value is to make the meter's pointer indicate full-scale-deflection
with a 5V EMF applied.

Robert's your mother's brother.
--
Chris Cox, N0UK/G4JEC NIC Handle: CC345
UnitedHealth Technologies, MN013-N300, UNIX Solutions Group
6150 Trenton Lane North, Plymouth, MN 55440 1-763-744-1723
email: (work) (home)
If at first you don't succeed, skydiving is not for you.

Scott wrote:
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.

Open up the meter movement and locate the resistor that is in series
with the meter movement. Using Ohm's Law, calculate what the correct
value is to make the meter's pointer indicate full-scale-deflection
with a 5V EMF applied.

Robert's your mother's brother.
--
Chris Cox, N0UK/G4JEC NIC Handle: CC345
UnitedHealth Technologies, MN013-N300, UNIX Solutions Group
6150 Trenton Lane North, Plymouth, MN 55440 1-763-744-1723
email: (work) (home)
If at first you don't succeed, skydiving is not for you.