Secondary heater voltage question

I recently bought a used dob. The secondary has a heater wired in it. Coming out of the secondary housing is a wire with a transistor on it that I assume is a temperature sensor or something, an LED, and power wires that terminate in a 9V battery type connector.

Any thoughts as to the proper voltage for this? E.g., can I connect to it using another 9V-type connector but use my standard 12v supply battery or do I need to step down the 12v to 9v for this? (I don't want to burn it out by accident).


Thanks.
- Mitch

Mitch,
That sounds like an Astrosystems dew remover and they opperate between 9-15v.
http://www.astrosystems.biz/dewgrd.htm
Got to this site for more info.
As for converting it, go to Radio Shack and buy a 9v battery clip (connector for 9v battery) and just plug it in like a battery and then route and attach the two wires to your 12v battery, simple.

hi Mitch

It sounds like it might be a custom secondary heater you have there. Are there any sort of numbers or markings on the 'transistor'?

Hopefully the system wasn't designed for 9V only (9V batteries have quite low amp-hour ratings). The power put out by the heater will be determined by the equation:

Power = (Volts^2)/Resistance

This means that if you increase the voltage from 9 to 12 volts, you increase the power by a factor of 1.78 (or more, since most 12V batteries sit at 14V when fully charged). Depending on the design of the heater, this might be a problem. If the heating elements are resistors, this might put them over their power rating - meaning they will get too hot and burn out. Are you able to see any of the heating elements, or are they hidden within the secondary holder?

Hope this helps...

Steve