Rechargeable Battery Powered Dew Heater Controller for DSLR Lenses

[Psychobilly]

I decided to add a Standalone Dew Heater Controller to my mobile Wide-field DSLR kit...

The units are "surplus" from a product we used to make and have a 6x2400 mAH NimH packs (protected by a 2A auto resetting polyfuse) They also contain an adjustable ultra low dropout voltage regulator that can be preset using multi turn pot on the PCB.

Currently at 6.5V output the unit is maintaining the body of the front of the lens around 8C above ambient and at this level would run the dew heater for 8 hours continously...

The unit fits inside a nylon pouch and is recharged using the wallwart and Charger module in a max of about 5-6 hours from dead flat..

I also use a similar unit (more cells) to run the DSLR's (get about 8 hours shutter open out of them as well) , the Synguider (set to 6.5V) and can even run the mount for a couple of hours from a 10 cell one set to 12.5V...

Peter...

[Psychobilly]

Comandeered the fridge and let a canon 18-55mm lens cool to 4C over about an hour giving a delta of Zero between the temperatures lens and the air...

With the output set to 4.5V (which is about 0.75W into the 4" Astrozap) the dew heater brought the Delta up to 7.5C after 30 mins

Need to try it in anger outside now...

Peter...