Orion Dew Heaters? - Page 2

Matty P (Matt) · #21 12-10-2008, 03:46 PM

Quote:

Originally Posted by AlexN

Matt, that all depends on your specific power requirements... Take a look at everything you intend to run off this power supply, find out their amp draw, add it all up, then add 1/3 of the total to the total....

Ie, if your equipment all totaled to 5A draw, add 1/3, making it 6.5A. That 1/3 allows for any surges by any of the gear etc, and gives you a little bit of head room should you want to power something else...

I know the EQ6 draws 2A, towards 4A during the start of a slew.... Dew heaters are power hungry, although I dont off the top of my head know their ratings.... Personally I'd lean towards the 8A one... Maybe buy a 5A as well just for posterity...

Alex.

Thanks for the info Alex. The 8A sounds like the goods.

I was just wondering how I will power the mount and the dew heaters at the same time as there is only one cigarette lighter adapter available?

AlexN · #22 12-10-2008, 04:30 PM

bintel sell a double adapter... $15...
I have one to run my mount and heaters off my field battery...

Matty P (Matt) · #23 12-10-2008, 04:36 PM

Quote:

Originally Posted by AlexN

bintel sell a double adapter... $15...
I have one to run my mount and heaters off my field battery...

Thanks for your help Alex.

AlexN · #24 12-10-2008, 04:41 PM

no probs mate.. All these things are things I wondered about a few months ago when I got serious about imaging.. So I've looked around a fair bit, and found most everything I've needed... Only thing I still NEEEEEEED is a HGM Titan or a Paramount... Sigh... cash issues.

erick (Eric) · #25 12-10-2008, 06:30 PM

Quote:

Originally Posted by AlexN

bintel sell a double adapter... $15...
I have one to run my mount and heaters off my field battery...

Much the same price in Dick Smith and Jaycar I think - check which store has one. I bought mine from the Dick

peter_4059 (Peter) · #26 12-10-2008, 07:35 PM

Are people having success powering the mount and dew heaters from the same supply? I've heard rumours of the dew heater PWM controller causing noise in the 12V supply which then affects the mount causing erratic slewing etc? I've got an independent supply for my dew heater as a precaution although I've not tried running everything from one supply.

AlexN · #27 12-10-2008, 08:09 PM

I've had no problems running them both of my 12v 17aH jump starter battery.. I've not tried powering them both off the same 240vac transformer though...

Will let you know later in the week.

Starkler (Geoff) · #28 12-10-2008, 08:18 PM

I would personally go for the 8A for $10 more just for the fact it has a cig lighter socket if thats whats needed.

Matty P (Matt) · #29 12-10-2008, 08:57 PM

I've been browsing the Bintel website and I came across the Kendrick Digifire 7 dew heater controller and Kendrick Firefly heaters.

All together the Kendrick heaters are cheaper than the Orion heaters so it might be worth a look. The controller looks very high quality and so do the heaters.

What do you think? Has anyone had any experience with these?

Go to the 3rd page of Telescope Accessories on the Bintel website.

Robbie · #30 13-10-2008, 04:04 PM

I have a set up from bintel regulated power supply/orion dew heater with cig sockets, cost about $150 the lot made up and shipped, It works fine with no hiccups or glitches, the slewing pulls like a train no problem.

shredder · #31 13-10-2008, 04:40 PM

I looked into these a while back when I had my C8 and wanted to drive the dew heater.

What I found was the dew heater would consume a lot of power in a single night (especially if it was cold). On warmer night it still consumed a lot of power but wasnt always needed.

The solution, as is obvious from other commercial products, is to regulate the power, which in turn will extend your battery life. If you look at these simple transformer options from JCar/TrickyDicky etc they are generally without regulation. They will consume power, as will your dew heater and together will consume it even quicker...

There are some options in controlling the power usage, but you have to choose carefully. The simple and cheap option is to use essentially a voltage divider style circuit, thus limiting the voltage (and so power) to the dew heater. The problem with this approach is that the dew heater is designed to operate at a specific voltage level (which translates to current level), without that current it wont heat at all. So by using a voltage divider you essentially go from full power to off with only a minor change in the voltage. The other problem with the voltage divider is that in the other half of the divider you end up consuming the power not used by the dew heater, again saving you nothing.

This is not how the commercial units are built, hence their added cost and complexity.

However their cost is not justified by the complexity of the circuit needed. What you really need is a voltage regulator that doesnt divide the voltage but divides the time its on (there is a technical name for this but it escapes me today). For example for 3 out of 5 sec its on at 12v and for 2 out of 5 sec its off. This allows for full current while on and no current while off. This gives much better heat regulation (provided you dont have the setting on and off in terms of minutes) while achieveing the all important battery life. This is essentially how the better commercial units do it.

In terms of complexity its actually not that difficult to make, and if you are somewhat capable with soldering its something you might like to try making. What you end up developing is a 555 timer circuit that drives the on off state timing, and a transistor that controls the voltage throughput. There are some good circuits on the web specifically for it (and for astronomy uses). Well worth a look.

I built one and I am sure it was only a couple of dollars worth of parts. The other advantage of this approach is with the same circuit you can control multiple outputs at the same time (just like the commercial ones).

Geoff45 (Geoff) · #32 16-10-2008, 09:08 PM

Quote:

Originally Posted by shredder

In terms of complexity its actually not that difficult to make, and if you are somewhat capable with soldering its something you might like to try making. What you end up developing is a 555 timer circuit that drives the on off state timing, and a transistor that controls the voltage throughput. There are some good circuits on the web specifically for it (and for astronomy uses). Well worth a look.

I built one and I am sure it was only a couple of dollars worth of parts. The other advantage of this approach is with the same circuit you can control multiple outputs at the same time (just like the commercial ones).

Yes, DYI is the way to go. Cheap and you can custom design it for your own gear. I built mine using the IIS articles http://www.iceinspace.com.au/63-285-0-0-1-0.html
and http://www.iceinspace.com.au/63-292-0-0-1-0.html
Geoff

shredder · #33 17-10-2008, 10:53 AM

Ahh, thats the name I was looking for "Pulse Width Modulation".... Dolt!

Anyway yes the make it yourself option is not bad if you are a little handy. Though I must say I was never so keen on the resistor dew heater, too many chances for problems, some form of resistance wire is a better solution.

Gem (Grant) · #34 16-05-2011, 07:44 AM

According to Kendrick, the micro firelite controller can handle 7a. The Bintel site says 1.5a. Does anyone have this controller? I am looking for an economical system for dew control.

Gem (Grant) · #35 16-05-2011, 07:52 AM

Ok, I should add that Kendrick has posted TWO specifications on the controller on their site. They post 1.5a http://www.kendrickastro.com/astro/d...teheaters.html
and 7a http://www.kendrickastro.com/astro/d...icroController

I hope someone can shed some light!

wasyoungonce (Brendan) · #36 16-05-2011, 09:49 AM

The 1.5A version is an older version designed to run one heater band only. The idea was to have the controller near the heater band.

The 7A version is a newer controller capable of much more I draw out. It is still single channel but with 2 outputs.

Why the change? Who knows..probably they save some $.

telemarker (Keith) · #37 16-05-2011, 10:15 AM

The 1.5A controller has outputs for 2 bands using the firelite plugs. The combined output cannot exceed 1.5A or you blow the fuse. I run a band for both an ED80 and 200mm SCT off the one controller (total of about 1.2A I think). I find these are enough for me during Canberra winters.

Regards
Keith