Re: 0-5vdc converted to 0-10vdc on the cheap

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

> Fred Smith wrote:
>
> >I have a control signal that varies from 0-5vdc and want to use it

on

> >another device that needs 0-10vdc. Fast control response is not
> >required.
> >
> >Available power is 5vdc and 12vdc both regulated.
> >
> >A solution that fits home-hobbyists budgets is required.
> >
> >What kinds of solutions can be used?
> >
> >An LM317 variable voltage regulator might be a possible solution
> >(certainly cheap).
> >
> >Is there a ready to go solution already available?
> >
> >
> I think this would be difficult with just a regulator chip. An OP

Amp

> is the tool of choice. Use a rail-to-rail op amp if you really

need to

> go all the way to zero. Or, power the op amp from +12 and -5 or -

12 V,

> so it can deliver zero volts when needed.
>
> The circuit would be to connect the 0-5 V input to the + input of

the

> op amp. Connect a 10 K resistor from the output to the - input.
> Connect another 10K resistor from the - input to the signal ground.
> The output will now swing from 0-10 V as the input goes from 0-5.
> You may need a small capacitor, say 100 pF in parallel from output
> to - input to stabilize the op amp.
>
> Jon

If you can get the rail to rail from Radio Shack, you can use a small
perf board and get it put together in short order.

If not, a 15 volt transformer with center tap would offer the ability
to get enough voltage spread for a 741 op-amp. it uses the negative
to get below zero and Forrest Mimms has a small booklet on op-amps
with circuits at radio shack.

still all fit on a perf board from RS

Dave