Changing DC level from a sensor

I have a sensor whose output varies from +2.5 volts DC to + 4.5volts DC. I would like to 'shift' this to become 0 - 2volts DC. Presumably with an op-amp? Single supply IC preferable e.g. LM358 Appreciate some advice on how to accomplish this.

JERD

Reply to
JERD
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Put a 2v zener ad a resistor in series across the output and take the reading off the resistors?

Reply to
terryc

simple summing network:

.--R--0V | in --R-o-+\ | >-o--- out 2.5V -R-o--/ | | | `--R--' dunno how close to 0V that'll go, use larger R if necessary.

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Reply to
Jasen Betts

You haven't said anything about the accuracy you require. Backing out 2 volts with a simple zener is likely to result in a fairly unstable zero point, as well as some added source resistance you may be better without. If you want something a bit better you could build a standard diff amp from a single supply opamp such as the one you suggest. Any opamp cookbook website will have a schematic.

Reply to
Noodnik

**Buy yourself a copy of Walt Jung's 'OP Amp Coookbook'. You can work it out for yourself. Alternatively, you can scan the Natsemi datasheets for some common OP amps. There will probably be an application note suitable for your needs.
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Trevor Wilson
www.rageaudio.com.au
Reply to
Trevor Wilson

Does it have to go down to zero?, if not, a resistor divider could work fine.

Reply to
Mark Harriss

Thanks for all replies of assistance.

My preference is for it to go to zero.

I am going to have a try of all of the suggestions and increase my knowledge at the same time. At age 68 the brain doesn't work as well as I would like these days!

JERD

Reply to
JERD

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