H-P (now called "Agilent") make some really good "linear" opto-couplers.
These have an LED and TWO photodiodes in the package - you use the second
photodiode to provide linearising feedback in your drive circuit.  HCNR 200
& 201 are the devices you want, and the Agilent website has some goos app
notes which should show you how it's done.

Chris

----- Original Message -----
From: "Peter Homann" <peter.homann@ADACEL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, November 29, 2002 12:41 AM
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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