Isolating an analog signal is more challenging because opto-isolators are
not linear.  Motorola used to have a linear opto coupler, HP has some
circuitry for making a linear opto.  A V/F converter with and opto isolator
to a F/V converter will do just fine. Buffer the output with an op amp,
i.e., 0p07, 0p37, and so on.  Pretty simple to implement.  Another way is a
simple charge pump with a 555 buffered output with LM324.    I do not know
what design constraints you have.  That will be your starting point.

Good luck,
Rich
----- Original Message -----
From: "Peter Homann" <peter.homann@ADACEL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, November 28, 2002 8:00 PM
Subject: Re: Generating an isolated 0-10Vdc voltage


> The 0-10Vdvc is only a control voltage. 2-3mA would be sufficient.
> Regulation, I'm not sure, probably 10 - 50mV would be OK.
>
>
> Peter Homann
> mailto:Peter.Homann@adacel.com
> Adacel Technologies Limited,
> 250 Bay St, BRIGHTON, 3186, AUSTRALIA
> http://www.adacel.com <http://www.adacel.com>
> Telephone +61 (3) 8530 7777, Facsimile +61 (3) 9596 2960
> Mobile 0421-601 665
>
>
> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Rich
> Sent: Friday, 29 November 2002 11:54 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Generating an isolated 0-10Vdc voltage
>
>
> What is the power delivered to the load, what is the regulation and
> accuracy?
>
> ----- Original Message -----
> From: "Peter Homann" <peter.homann@ADACEL.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Thursday, November 28, 2002 7:41 PM
> Subject: [EE]: Generating an isolated 0-10Vdc voltage
>
>
> > Hi,
> >
> > I'm planning to generate a 0-10V analog voltage using the PIC PWM, RC
> > filter, and op-amp.
> >
> > The question is how do I isolate the output voltage. The voltage is to
> drive
> > a 90V DC motor controller where the controller ground is live.
> >
> > One solution is to opto-isolate the inputs to the PIC and have the whole
> > circuit live. I would have to power the PIC circuit via a 12V zener and
> > resistor.
> >
> > The other option is to isolate the 10V signal via a transformer. Does
> anyone
> > have experience with this or other alternatives?
> >
> > Thanks,
> >
> >
> > Peter Homann
> > mailto:Peter.Homann@adacel.com
> > Adacel Technologies Limited,
> > 250 Bay St, BRIGHTON, 3186, AUSTRALIA
> > http://www.adacel.com <http://www.adacel.com>
> > Telephone +61 (3) 8530 7777, Facsimile +61 (3) 9596 2960
> > Mobile 0421-601 665
> >
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