DIY dew heater

[Anthonyexmouth]

What would be a safe kinda temp for a homemade, unregulated dew strap? Will sort a controller at some point but just made one and was wondering how hot it should get. 

[wimvb]

If it gets comfortably warm when you hold it in your hand, it won't be too warm when on a scope. The heater only as to be warm enough to prevent dew, not to evaporate it. Obviously a large scope needs a more powerful one than a small scope.

[Anthonyexmouth]

I guess it feels like one of those chemical heat pads, maybe a little warmer but not really hot. Guess I could just put another layer of gaffer tape if it gets too hot

[wimvb]

This is a cheap way to control the power

https://www.amazon.com/Jkl-Components-ZDM-01-Dimmer-Dial/dp/B00R3QQKTY

[Mick J]

Comprehensive guide to making your own here https://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater-bands/

[Paul73]

If you are building your own controller, make sure that you use a PWM type which reduces the power consumption while delivering similar heat. I use resistors in paralel to provide the heat. They are virtually free!

Paul

[Anthonyexmouth]

1 hour ago, Mick J said:

Comprehensive guide to making your own here https://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater-bands/

i saw this site and made the nichrome wire one, the one you posted is a bit easier to read. 

[Anthonyexmouth]

29 minutes ago, Paul73 said:

If you are building your own controller, make sure that you use a PWM type which reduces the power consumption while delivering similar heat. I use resistors in paralel to provide the heat. They are virtually free!

Paul

i went with nichrome wire and masking tape, 10m of wire was only £3 on ebay. got enough to make heat pad to keep under my telescope cover to keep it dry. 

[Paul73]

Can’t argue with £3! Probably easier to work with than the resistors too.

[Anthonyexmouth]

22 minutes ago, Paul73 said:

Can’t argue with £3! Probably easier to work with than the resistors too.

yeah, just lay the gaffer tape down flat and stick the wire to it. i'll do it slightly neater next time but you don't see it when its wrapped anyway. 

[barkis]

Hitecastro do a 4 channel dew  controller which I use myself. 
There is a heat control for each output . A control knob for each one allows you to heat the dew strap to the temp
you want. You can also ake your own straps too, using Nichrome  wire. the wire comes  in differing resistance,  per foot
so you can workout how much current will  flow  from a 12 volt supply using Ohms Law. You can set a maximum limit, which can be reduced  by the controller  knobs
Bit of a Faff I know, that's why most folks buy ready made.

Ron.

[Anthonyexmouth]

Just now, barkis said:

Hitecastro do a 4 channel dew  controller which I use myself. 
There is a heat control for each output . A control knob for each one allows you to heat the dew strap to the temp
you want. You can also ake your own straps too, using Nichrome  wire. the wire comes  in differing resistance,  per foot
so you can workout how much current will  flow  from a 12 volt supply using Ohms Law. You can set a maximum limit, which can be reduced  by the controller  knobs
Bit of a Faff I know, that's why most folks buy ready made.

Ron.

made a couple of nichrome wire/masking tape bands yesterday. need to pick up some supple silicone wire tomorrow, will run them unregulated at first and then build a controller later.