Telescope Dew Controllers and 12v Power Supplies

Posted by XTSee on 29th January , 2012

I did some research a while back for best options for controlling dew on my Celestron C6 SCT scope, and also recently a friend asked for some advice.

These are sites I like generally, I buy from them and they often have good deals….
and of course always worth checking Amazon/Ebay.

Some links to dew controller bands and control boxes.

Dew heater tapes….

8inch is £38.50 (you can shop around but I don’t think you’ll find a much better price)
They have other sizes for finder scopes, eyepieces, binoviewers, etc
I got a simple 2 port dew controller box from Ebay….
These were originally priced at £27, then I bought mine at £29, now they’ve gone up to £35, bloomin cheek!
FLO also do same one, but at £39

Single port (bit pointless, might as well pay extra for 2 or more ports)…

Or a 4-port on ebay
when at home and with extension lead this decent mains unit gives up to 5Amps (dew controllers draw a lot of current)…
or you can get one of the myriad cheap 12v battery units off Ebay for around £25
generally they have 17Ah lead acid batteries ie. 1amp will be supplied for 17hours, 2amps for 8.5hrs, and considering dew controllers eat power up when you’re using several dew controllers at once, mine use about 3amps, your power might go in 4 or 5 hours. Units with higher Ah rating and more features really jump up in price, e.g £70-£300!!
Maplin also do all kinds of very nice looking power units (with meters, USB sockets, lights, cooling fans, posh looking), which are tempting but I think its much better to go for the simpler option of buying 2 x £25 units than one £99 unit!

Because …..I’ve had problems where my scope and dew controllers were plugged into just one battery unit. Problem is that as the battery drains, the voltage drops a bit, and although the scope doesn’t require much amperage, the drop in voltage can cause the scopes motor control electronics to pack in/reset, at which point you can say bye bye to an observing session, because your star alignment has gone.
So I have got 2 battery packs, one dedicated to scope, etc, and one solely for dew control.
If your dew control battery runs out, well you still have maybe half hour or more before dew starts forming again and meanwhile the scope keeps running ok.
Otherwise when at home I use the Maplin 240v to 12v unit for uninterrupted power.
I’ve also got one of these for rapid dew removal (all around £12 - £14, but watch the postage cost too) …

Hope this gives some ideas.

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