My (under) $15 Dew Controller...

acropolite (Phil) · #1 12-10-2005, 07:00 PM

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.....

davidpretorius · #2 12-10-2005, 07:06 PM

nice work!

RAJAH235 · #3 13-10-2005, 12:35 AM

& you don't even need a heatsink! Used an Al. cover.

Looks good Phil.

L.
ps. Have made a few for the W.A.A.C.ers.

Hitchhiker · #4 17-10-2005, 05:42 PM

Good work acropolite!

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.

Mine has certainly saved me on many a dewy night!

Hitchhiker · #5 18-10-2005, 02:43 PM

Seems the IceInSpace censor got to my last post!

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.