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. Look at it this way. Standard coolers manufactured by Melcor consist of (IIRC) 128 elements connected in series electrically but connected in parallel thermally. Come to think of it - the only problem I can see is if the modules are somewhat different and do not drop the same voltage. This will cause the higher resistance modules to dissipate more power than the lower. You should be able to easily measure to see if this occurs and if it is a problem. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (403) 489-3199 voice (403) 487-6397 fax