Telescope Reviews: $27 DIY 6 channel dew heater/fan controller.

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MessiToM
professor emeritus

Reged: 12/21/09

Loc: Huntingdon PA

$27 DIY 6 channel dew heater/fan controller.
#5658881 - 02/02/13 08:33 PM

I wanted a dew heater controller and a way to vary fan speed to my boundary layer fans.

I saw some cheap p.c fan controllers and figured I would give one a shot

This http://www.amazon.com/gp/product/B004LKZESI/ref=oh_details_o00_s00_i00 fan controller is $27 and has
6 Channel Manual Control
Max Output 30W per Channel
PWM Control
Rheostats instead of pots.

The unit

Nice heat sinks on the mosfets

I bent up some sheet metal to make a case for it

to monitor my batteries voltage I put one of these in

You can see the volt meter powerd up here along with the 6 output channels

The controller came with all but 2 of the 3 pin female fan conector plugs. They are cheap on ebay. here is a pic of how I mated them to be used with my dew equipment that uses RCA plugs

I then made a back plate for the case out of wood to glue them and the volt meter into.

The box also included a Molex power plug you can use to power the unit up. It is tiny gauge wire so I took the plug apart to upgrade the wire gauge. Here is a pin-out to hook the back fan/molex connector wires to
left are the fan connectors. right molex connector

YOU NEED
the unit
Metal/wood to make the case
Female RCA plugs. 6
2 pin fan connectors. 2
solder, soldering pen
various wire.

So far Ive used it briefly. Ive powered the unit up with all 6 channels wide open. No smoke/smell. Dew heaters and fans are getting plenty of variable power

Edited by MessiToM (02/02/13 08:38 PM)

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roscoe
curmudgeon

Reged: 02/04/09

Loc: NW Mass, inches from VT

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: MessiToM]
#5659461 - 02/03/13 07:33 AM

Nice find!
Are all 6 channels the same output wattage? Are they a pulsed output like many dew controllers, or a continuously variable voltage? Do the LED's hiding in the front panel vary in intensity to match the output voltage? Where did you find that voltmeter module? Was that enough questions?

Thanks, Russ

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MessiToM
professor emeritus

Reged: 12/21/09

Loc: Huntingdon PA

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: roscoe]
#5659698 - 02/03/13 10:39 AM

It's ok. I don't mind.

All channels are 30watts
LEDs don't change intensity and are a smidge bright but seem easily covered over slightly if they are to bright.
No pulsing.
Voltmeter was from eBay

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ccs_hello
Postmaster

Reged: 07/03/04

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: MessiToM]
#5660377 - 02/03/13 05:10 PM

$27 shipped is a great price for 6 channels. Usually this type has 4-pin PWM fan-control in, and
3-pin DC-fan out (covert the old fan to be used by the modern PC's 4-pin control method. A manual override is to use knob to adjust the speed.

I have a one-channel version which costs about $10 shipped

few years ago.

Each channel is using a logic-level PowerMOS to "chop" the output voltage to drive the load (fan or heater).
I saw from the picture there is no output filtering capacitors which means the output drive is PWM style. Add a large capacitor (one per channel), it becomes the variable voltage output type.

Clear Skies!

ccs_hello

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Spiritcrisis
newbie

Reged: 02/09/13

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: ccs_hello]
#5671008 - 02/09/13 04:35 PM

How are you powering this?

Im assuming something like this...

http://www.amazon.com/Logisys-Cigarette-Plug-Molex-Cable/dp/B00459ARHI/ref=sr...

Edited by Spiritcrisis (02/09/13 05:04 PM)

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Raginar
Carpal Tunnel

Reged: 10/19/10

Loc: Rapid CIty, SD

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Spiritcrisis]
#5672752 - 02/10/13 05:44 PM

How are you powering it?

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ccs_hello
Postmaster

Reged: 07/03/04

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Raginar]
#5672764 - 02/10/13 05:52 PM

The 6-ch unit is powered by this power feed (ref. first post), right-hand side (4-pin Molex). Just need 12V and ground.

The other end can be whatever that your DC 12V power source is using. E.g., The cigarette light plug as in AMZ link two posts above.

Clear Skies!

ccs_hello

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Spiritcrisis
newbie

Reged: 02/09/13

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: ccs_hello]
#5672952 - 02/10/13 07:50 PM

Im assuming that the volt meter is set parallel to the voltage input so it monitors on the input and not the out put correct?

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korborh
professor emeritus

Reged: 01/29/11

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Spiritcrisis]
#5672966 - 02/10/13 08:01 PM

Great find!

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ccs_hello
Postmaster

Reged: 07/03/04

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Spiritcrisis]
#5673624 - 02/11/13 08:34 AM

Quote:

Im assuming that the volt meter is set parallel to the voltage input so it monitors on the input and not the out put correct?

Yes, per original poster's picture, it is measuring theinput voltage (parallel to power feed.)

BTW, the device used seems to be identical to a PC hobby voltage displaying device (very inexpensive.)
The one I have (looks identical) has about +- 0.1 to 0.2V deviation to actual. For the price and once you know the habit (so mentally compensate it), it is fine.

Clear Skies!

ccs_hello

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Achernar
Postmaster

Reged: 02/25/06

Loc: Mobile, Alabama, USA

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: MessiToM]
#5673632 - 02/11/13 08:42 AM

Make sure you put a fuse in series with all of the outputs, in other words between the battery and the controller of the appropriate rating for all the heater strips you plan to use. A short circuit will allow a massive amount of current to flow, and that can blow your battery up, or otherwise do damage. A pair of 12-volt-batteries can be uses to TIG weld metal, don't do that on your telescope. Shorts can develop in dew heaters, often at the RCA jack.

Taras

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Spiritcrisis
newbie

Reged: 02/09/13

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Achernar]
#5675090 - 02/12/13 12:58 AM

Very good point. Thanks for mentioning that. I already have the fan controller, resistors, wire, and power supply ordered. Just did some EIRP to find my total Amp pull and Wattage output and I should be good.

Thanks all for the insight

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: ccs_hello]
#5675111 - 02/12/13 01:08 AM

Quote:

Each channel is using a logic-level PowerMOS to "chop" the output voltage to drive the load (fan or heater).
I saw from the picture there is no output filtering capacitors which means the output drive is PWM style. Add a large capacitor (one per channel), it becomes the variable voltage output type.

Clear Skies!

ccs_hello

For those of us who can just barely get the polarity right and maybe do a little soldering

Would you please explain how to "Add a large capacitor"?

I gather I need to solder one end of a cap onto one of the leads of each channel, and then the other (to ground?).

TIA

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ccs_hello
Postmaster

Reged: 07/03/04

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Tom and Beth]
#5675407 - 02/12/13 08:46 AM

If you want to get the filtered DC output and less RF Interference, ...

Put a 220uF (or 470uFD) 16V capacitor on the output side (6 total, one ch each). "Plus" goes to the output and "Minus" goes to the Ground.

Clear Skies!

ccs_hello

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: ccs_hello]
#5676254 - 02/12/13 04:46 PM

Thank you.

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MessiToM
professor emeritus

Reged: 12/21/09

Loc: Huntingdon PA

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: ccs_hello]
#5676265 - 02/12/13 04:51 PM

wow alot of replies since i last looked. "ccs_hello" you are correct in every question you answered. Thank you.

YES i have a fuse about an inch off my positive battery terminal.

It has push-button switches to power each channel on or off as you can see in the pic. I wasnt using all the channels

Green = on Red = off
Red led's are a bit bright and I may dim them down

The volt meter is a little bright to and I may make a flap to cover it or tint it some.

ONLY GRIPES
Semi bright led's
knobs are a little stiff to turn when the unit is cold. I was using it the other morning and it was 10 degrees

Edited by MessiToM (02/12/13 04:53 PM)

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MessiToM
professor emeritus

Reged: 12/21/09

Loc: Huntingdon PA

Re: $27 DIY 6 channel dew heater/fan controller. new

new

[Re: MessiToM]
#5676281 - 02/12/13 04:56 PM

I forgot. I power it by 2 7AH batteries going up through the inside of my truss poles. As I stated I have the hot lead fused close to the battery.

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Tom and Beth
Carpal Tunnel

Reged: 01/08/07

Loc: Tucson, AZ

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: MessiToM]
#5676371 - 02/12/13 06:03 PM

Maybe you can use one of those unused channels to trim the brightness of the LEDs?

I like what you did with it. Looks "kewl"

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Spiritcrisis
newbie

Reged: 02/09/13

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: MessiToM]
#5690140 - 02/20/13 02:42 AM

Any tips on building the case for this? I love how you did yours and any insight you could give me on how you did that would be great.

Thanks for making this post by the way... I have already bought all the parts put together the strips and testing them on a powered breadboard. Only thing left is to test the main unit for power failure and figure out how to case it.

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MessiToM
professor emeritus

Reged: 12/21/09

Loc: Huntingdon PA

Re: $27 DIY 6 channel dew heater/fan controller. new

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[Re: Spiritcrisis]
#5691554 - 02/20/13 07:05 PM

I just measured the length and width I needed then cut out some thin sheet metal. I used threaded screw holes on the unit's case to secure the metal box to around the unit. I back piece is mad out of wood for ease of cutting all the cirles

your welcome too : )

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