Zero Cost Dew Heaters For LX200 Telescopes

Telescopes and dew Introduction

On my other dew page I discuss the problems and solutions to keeping the my telescope dew free with a number of low cost fixes that don't require splashing out wodges of cash on expensive kit.

Lately we have become fed up of dew forming on the corrector plate of our LX200, and on my guidescope and finderscopes. Those frequent trips outside with the hairdrier were beginning to get boring. So we set out to find a solution.

Enter the electric toaster

After some thought we decided to try a very simple approach. A short drive to the local domestic tip produced a free electric toaster of unknown age. After something of a struggle (consisting of Pete hitting it with a hammer until it yielded), we dismantled it, and extracted the heater element wire. We then cut an 80cm length of this wire and attached it to an old PC power supply. At 12volts it draw about 0.5 amps. This corresponds roughly to about 6 watts of heating.

Of course, normally the element in a toaster is run at a much higher voltage - and produces heat conducive to making toast. We are not making toast, we are making a dew heater for a telescope. Hence we can get away with a lot less volts.

I will always take an opportunity to sing the praises of an old PC power supply. This wonderful gadgets are fantastic for DIY astronomy. They provide 12v, 5v and 3.3v with more amps than you care to think about. The best thing is, the older models are not suitable for the newer breed of computers. So the local dump is a great place to find them Take away an old computer case. Remove the power supply, and throw away the case (or use the metal for a project).

Completed Dew Heater for LX200 telescope

The project was completed by running a length of the heater wire around the inside rim of the LX200, just above the corrector plate. The wire was held in place by black electrical tape. Electric supply from the PC power supply was wired in, and the nights observing started. At no point did we have to resort to the hair dryer - the corrector plate stayed clear of dew and moisture all night.

A few shots (click for large version) of the toaster itself, the internal heater wire, and the LX200 with its gaffer tape.

Page last updated 2005-09-20