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Would you please be so kind to assist with a circuit to let the curent feed to a peltier alternate. This is to let the peltier heat up onecside (cold other) for say 10sec and then reverse current so it can go cold (hot other side) for 10sec and so forth.

If memory serves, EFFICIENT Peltier modules have their faces dedicated ( to the cold side or to the warm side) so you would need two modules. A possible solution is to use diodes (assuming the source can supply +12V to -12V)

You can technically use only D1 and D4, removing the two other diodes. You are more likely to reach a "midrange" temperature for all practical purpose, since heat exchange is slow and the whole configuration will act like a PWM does when is applied to a LED: an average is obtained for all practical purposes.

I tha k you for your time, effort and input. Much appriciated. I must just add that I will need to use a 12V DC supply that I wish to alternate in 10sec intervals on only one peltier irrespective of pervormance. Kindest regards.

You have the datasheet/specs of that Peltier module?

From Tec2med (medical equipment site):

"The continuous variation in the heating and cooling action will cause the module to rupture quickly."

That is why I strongly suggest to use 2 modules, each one with a dedicated function (one cooling, one heating).

Ding_Dong---Could you please elaborate a bit (perhaps quite a bit) on what you are doing. In particular tell us the current you expect and the results you are aiming for. My own approach, given what I read between the lines would be to use one of the Arduino controllers and transistor or mosfet switches to get the required current. This has the advantage of simplicity and low cost and would make it easy to add a temperature regulator if this became necessary. But this all depends on what you are doing. I put to-gether a heat control for plastics recycling along these lines and it worked like a charm.

Thank you guys. I came right using a 555 as a timer. (ON/OFF Pulse times can be set with resistors, independently). This feeds a H-Brigde with 2 x N-Type Mosfets and 2 x P-type Mosfets to the peltier (motor, bi-directional). I cant seem to paste the circuit pic here, but this works. I concur with vanderghast that the continuous variation in the heating and cooling action will cause the module to rupture quickly. This I will set to the test though, else use two separate ones, that is not ideal but will work.

Thanks again. j