On Sat, 23 Jan 1999 14:10:01 -0700, you wrote:

>Gerry Cox wrote:
>
>>I am using a PIC as a controller for TEC (peltier) devices. I monitor
>>various temperatures and adjust a constant DC current to achieve the
>>required results. Eight (identical) peltier devices are assembled to a 'cold
>>plate' thermally in parallel. Electrically they are in series and they draw
>>approx 2A from the 12V supply.
>
>Sounds fine to me.  I did some research into the application of peltier
>devices used as generators several years back and don't remember any such
>problems that your co-worker mentioned.  The only thing that I found
>non-intuitive was that TE coolers do NOT like PWM power - I always found
>better efficiency if the PWM was smoothed to DC first.
Could this be due to them acting as a generator when off ? Would
shorting the pins during the 'off' cycle help?