After noticing Exfso's artificial star I thought some IISers might be interested in a cheapo dew heater controller. I bought my dew strap from scopestuff in the US to save the hassle of making one as they were only $35 US. Dew controllers however are much more expensive so I opted (for power efficiency reasons) to make a simple PWM controller which I found on the following website. http://www.backyard-astro.com/equipm...l#Anchor-49575
For those interested on the site there is also a simple (and elegant) dew heater using nichrome wire and a piece of silicone tube. I used veroboard rather than making a PCB and put together the beasty in a couple of hours. The unit switches slowly to minimise interference with tracking electronics and is about as simple as it gets. I'm not really sure of the exact cost as I already had the jiffy box, knob and power socket, but it cost me well under $10 for the bits I had to buy. I used a 2.2 microfarad cap in lieu of the 1.5 and a BD681 in lieu of the TIP120....Next project is a multi port model.....
For those who want to build a Pulse Width Modulated power supply without creating there own printed circuit board or mucking around with veroboard, **** Smith sell a Motor Speed Control kit for about $24 (Catalogue no is K3072). The intended application is to drive 12V motors but it works just as well as a Dew Zapper controller. All components and a printed circuit board are included.
The power controller kit is available from ****SmithElectronics.
The same kit is also available from Jaycar electronics - both kits are based on an article from an Electronics mag called Silicon Chip. If you buy 5 or more kits from Jaycar you get a couple of dollars discount.
Looks good Phil. 
L.
