cheap dew heaters

[that_guy]

Hey guys, looking for a cheap solution for dew problems for my ed80 and finder guider. found these on ebay that run off of usb (so using power banks). i know they dont run as hot as dew zappers that are more expensive, but do you think they'll work okay if left on constantly?

http://www.ebay.com.au/itm/2-x-USB-Digital-Camera-Dew-Lens-Heater-Strip-Frame-Heater-Telescope-Cup-Warmer-/292089909562?hash=item4401ea513a:g: 94cAAOSwRUhY9s0q

[Malcolm]

At that price, worth a try.

[AstroApprentice]

Hi, I use the following USB dew heater:
http://www.teleskop-express.de/shop/product_info.php/info/p8570_AST-Optics-USB-Heating-Collar--11-cm-length.html
I originally bought it as it was reasonably priced and no controller needed. Plus I have USB on mount. Works well, but if anything it gets a bit too hot. I've been planning to write a review on it as I have a thermal imager and a couple of thermocouples. Imager shows there are some cold spots, but heat distribution is otherwise pretty good. When Run off 2.1 A USB it gets to 40 C or so, but off 1 A, around 30 C so there is a limited ability to regulate heat.
Still, I'm thinking about upgrading to a USB-focus Dewpoint controller when I upgrade my imaging scope.

[OzEclipse]

The limited regulation is because you are using the current limit on the USB to control. Use the USB output to power a variable voltage power supply and control the power output from that. Cut the power cord off leaving some lead on each. Where you cut depends on where you want to mount the variable voltage controller. Buy a buck converter DC-DC converter like this. The more of these you order, the cheaper they are.

http://www.ebay.com.au/itm/LM2596-Voltage-Regulator-DC-DC-Buck-Converter-Adjustable-Step-Down-Module-/161934554531?var=&hash=item25b40d35a3:m:mJyGflWXlgzVs xe5Xt0xQfw
(http://www.ebay.com.au/itm/LM2596-Voltage-Regulator-DC-DC-Buck-Converter-Adjustable-Step-Down-Module-/161934554531?var=&hash=item25b40d35a3:m:mJyGflWXlgzVs xe5Xt0xQfw)
Input Voltage: 3.2V-40V
Output Voltage: 1.25V-35V
Output Current: rated current is 2A, maximum 3A(additional heat sink is required)
Conversion Efficiency: 92%( highest)

[Wavytone]

I'm wondering if anyone has tried something like these reptile heat packs:

http://www.aquaholicsonline.com.au/nomey-pet-aquarium-retile-shipping-heat-pack-40-hours-10-pack-2-bonus.html

Would suit a larger scope or eyepiece case.

[axle01]

Just ordered 2 worth a try.

Al

[glend]

I have used the hand warmer versions of these. They do get pretty hot quickly but there is obviously no regulation capability if you want it to sit just warm enough to hold a surface above dew point. They do last for an hour or so at peak heat but are one time only use. The ones sold at various Chemists in the winter, including smaller toe warmer pads, are worth investigating.

[that_guy]

nice, let me know how they go.

[stefang]

From the Kendrick website.

POWER SUPPLY AMP HOUR RATINGS
Please bear in mind that when using this chart to determine what size of power supply (as opposed to a battery) to choose, you will need to use the full amperage rating of the heaters in question. The heaters will draw their full amperage when turned on and unlike battery operation, the amperage cannot be averaged by the % of your programmed controller settings.

All figures are in amps

Telrad Heater 0.4
Telrad Finder Heater 0.2
.965" 0.2
1.25" 0.2
2" 0.3
3" 0.8
4" 0.9
5" 1.2
6" 1.4
7-8" 1.5
10" 1.9
11" 2.3
12" 2.6
14-16" 4.1

DIAGONAL MIRROR HEATERS
S2 0.2
S3 0.3
S4 0.7

PRIMARY MIRROR HEATERS
P8 0.8
P10 0.9
P12 2.6
P16 4.5

OTHERS
Control Pad Heater 0.6
Laptop Heater 3.0
Eyepiece box heater 0.8

[kittenshark]

Ditto hand warmers/reptile heater.

Daiso (Japanese discount store) sells hand warmers with an adhesive backing (useful!) for 6 or 8 pieces per pack for $2.80. These don't get as hot as the more expensive ones you find in the pharmacy or pet store so they might be more suitable.

Pros:
-Cheap and very warm and last all night
-useful as a, well, hand warmer.
-you can give them away and make new best friends!
Cons:
-it's disposable so it's gonna cost you every time you use it, and you have to remember to have new ones with you every night.
-might be too hot for your optics' liking and you can't really regulate the heat
-can be too bulky
-have a use-by date

[Windston]

Mate if you like I could make you some 12v nichrome wire dew heaters and send them to you that I know can heat better than those USB ones just based on the pure USB power limit!

I could probs do it for less than or equal to the 30$ shipped as well, all wrapped up in canvas so they look nice etc of course! :thumbsup:

[that_guy]

I would take up that offer in a heartbeat, but alas I'm currently overseas. I'll send you a pm when I get back ~3 weeks if the offer stills stands!

[jak001]

I got one of these, works well it's 12v and has low and high temps. I've only ever used it on high though, low seems useless
http://www.ebay.com.au/itm/272441059653?

[astroron]

I have just received two I ordered,took about two weeks to get them from China but no worries about that
I have not tested them on my Vixon 81mm Binoscope,but wrapped one round my wrist for about 15 minutes"they say they are good for sore wrists etc"
It didn't get very hot,but I think it will be sufficient to keep the dew of the main lens.
It will be interesting how long the power bank will last:question:
It is a Sygnify 12000mAh
Input DC 5V 1A
Output DC 5V= 3A(max)
Seems to me to be OK.
One question:question:
Will I need two powerbanks,or can I use the powerbank with two USB's attached.:question:
Any helpful comments will be much appreciated.
Cheers:thumbsup:

PS, there is no information on what the heaters draw, in fact there is no information at all
about the product,It is nameless. :O

[that_guy]

Yeah, thats what I thought too ron, next to no information regarding the item. Let us know how they perform in the field. I would assume they draw the same amount of power as whatever your powerbank is rated for (i.e. 2A or 1A).

[Weird1]

Found these on the Web, for those who are sick of too many cables
http://www.tech2000astronomy.com/zap/

Cheers Keith :thumbsup:

[astroron]

There is no photo in that link:shrug:
Cheers:thumbsup:

[astroron]

:thanx: Tony.
Cheers:thumbsup:

[Weird1]

Link does work for me using Firefox.
Cheers

[astroron]

I use google chrome and it doesn't work ,no matter you pic shows it all and it really aint for me.
Thanks anyway. :thanx:
Cheers:thumbsup: