[Renato1 (Renato)]

I used to have resistors attached inside my dewshield of my SCT. It worked okay, but I still had the problem of eyepieces, finderscope and Telrad dewing over, on which I was using a 12 volt hairdryer plugged into a power pack.

I don't do astrophotography, so nowadays I just use a 12 volt hairdryer plugged into my Projecta battery starter and blow the dew off all of them. Obviously, I have to do it more frequently on more dewy nights.

Only problem I rang into was that some power packs wouldn't power the hair dryer through their 12 Volt sockets, so back then had to rig the wires of a 12 volt socket extension lead to jumper cables.

Mine is not an elgant solution - but it's quick - and the 12 volt hairdryers don't cost much on Ebay.
Regards,
Renato