Try a capacitor dropper, rather than the resistor to feed your zener - you'll get less heat. Chris ----- Original Message ----- From: "Peter Homann" To: Sent: Friday, November 29, 2002 1:07 AM Subject: Re: [EE]: Generating an isolated 0-10Vdc voltage > Thanks for the reply, > > The 2nd option sounds OK. I'll still need to create a 12Vdc supply for the > filter circuit and opamp buffer. > > Any other suggestions for generating the 12V supply from the 120Vac input. > My plan is to use a Zener and series power resistor to drop the voltage. > > > Peter Homann > mailto:Peter.Homann@adacel.com > Adacel Technologies Limited, > 250 Bay St, BRIGHTON, 3186, AUSTRALIA > 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 Wouter van Ooijen > Sent: Friday, 29 November 2002 11:54 AM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]: Generating an isolated 0-10Vdc voltage > > > > 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. > > Use a dual optocoupler. I don't know what the term is for this circuit, > but the second coupler is put in the feedback loop on the HV side to > make the transfer independent of the coupler's characteristic, provided > that the two couplers have the same characteristic. > > Or (avoid the problem instead of solving it) put the PWM signal through > an optocoupler (or trafo), do the filtering on the HV side. > > Wouter van Ooijen > > -- ------------------------------------------- > Van Ooijen Technische Informatica: www.voti.nl > consultancy, development, PICmicro products > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics