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Dew heater control box finished

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19 replies to this topic

#1 Hook

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Posted 22 August 2019 - 04:14 AM

I have completed all my dew heater requirements. 2 heater strips and the control box.

 

I printed out the control box on my 3d printer to my exact requirements. Came out superb. Here's the pics..

 

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#2 Neptune

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Posted 22 August 2019 - 06:19 AM

You did a very nice job.  Is it all home made?  Do you have plans for it so others could try to make one?

David


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#3 wrvond

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Posted 22 August 2019 - 07:59 AM

That looks great!

What gauge wire did you end up using in your heater strips? 



#4 Hook

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Posted 22 August 2019 - 12:19 PM

You did a very nice job.  Is it all home made?  Do you have plans for it so others could try to make one?

David

All home made.

 

I have the 3d print stl file for the box. The electronics are from China, about 2euro per piece....or less. Nichrome wire was around 4-5 euro, but have plenty left over. Fabric for heater strips can be anything you have, but I purchased black velour. No plans needed, all electronic components are marked + and - in, and + and - out. The 2 temp units are just relay units with 3 buttons to set the temp you want it to switch power off, again they are marked with + and - in, and the other 2 connections are the relay jumper to connect the - out to strips, the + to strips comes out the pwm + out, which also feeds the temp relays. Pretty straight forward.

 

I had intended to put compression springs onto those 3 buttons on the temp relay, which I made with some of the nichrome wire left over.....and it was so easy to make them. I was going to print off 6 push rods to adjust them from the outside of the box, (hence my 6 holes in the lid),......but I buggered up my measurements on one of the temp units, so I had to forgo that.........no way I was going to do another 7 hour print. Anyhow, the lid fits tight and no screws will be needed in the 4 corners, (for which I had made holes for). So it is easy enough to set the temp, close the lid, and carry on.

 

All the fittings for the rca plugs and power in plug were all from china, and came in packs of 5-10.......so plenty left over.

 

Probably cost me roughly 15 euro if you were to put aside all the over-stock I am left with, plus time. Not much soldering to do. I notice a .2 difference between probes, (in temp), so no worries there. I am currently running the set-up on my scope as I type, primary mirror 26.1, secondary 25. Outside temp 22. Had them on now for around 30 mins.

 

I recommend anyone wanting heater strips and controller to d.i.y. and take your time. Just get measurements right if you plan on printing the box. I did print it with raised nubules inside to sit the boards on........they were fine in measurement. The lid has 2 rectangular down chutes which sit over the temp led's, and I glued a piece of clear acrylic thin sheet to the top to prevent water ingress.


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#5 Hook

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Posted 22 August 2019 - 12:23 PM

That looks great!

What gauge wire did you end up using in your heater strips? 

All the details on my post in making them

 

https://www.cloudyni...ater-completed/



#6 don clement

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Posted 22 August 2019 - 05:10 PM

For a dew heater application of this type, refractory metal nichrome wire isn't really needed and can't be soldered. A set of  axially leaded metal film or carbon resistors soldered together would work just as well. BTW How many remember the resistor color code? http://www.resistorg...or_codes_chart/

 

Don

 

IMG_0689WEB.jpg

 

IMG_0688WEB.jpg


Edited by don clement, 22 August 2019 - 05:14 PM.

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#7 Pinbout

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Posted 22 August 2019 - 05:16 PM

For a dew heater application of this type, nichrome wire isn't really needed. A set of  axially leaded metal film or carbon resistors soldered together would work just as well. BTW How many remember the resistor color code? http://www.resistorg...or_codes_chart/

 

Don

 

attachicon.gif IMG_0689WEB.jpg

 

attachicon.gif IMG_0688WEB.jpg

Come on touch it... just touch it lol.gif lol.gif

 

https://youtu.be/gktcofMz0qI


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#8 don clement

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Posted 22 August 2019 - 05:40 PM

My favorite is to use resistive heating coating or paint. https://www.coating-...-heating-paint/

 

Don



#9 OldManSky

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Posted 22 August 2019 - 06:21 PM

BTW How many remember the resistor color code?

I do, I do! :)

First-year EE classes, back in "the day."  It was a part of a midterm and a final.

I can still read 'em on sight nearly 40 years later...



#10 BGRE

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Posted 22 August 2019 - 06:38 PM

I've successfully soft soldered lots of nichrome wire.

However I prepared the wire ends by fusing a layer of  brazing rod to the ends first using suitable flux and an oxy-acetylene torch. Excess flux is removed before soft soldering.

The brass like layer can be easily soft soldered. 


Edited by BGRE, 22 August 2019 - 06:39 PM.


#11 Pinbout

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Posted 22 August 2019 - 06:45 PM

To keep few off you don’t need much heat at all, but once you get some dew, you have to blast it. 

From Mr. Protostar 



#12 don clement

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Posted 22 August 2019 - 07:06 PM

To keep few off you don’t need much heat at all, but once you get some dew, you have to blast it. 

From Mr. Protostar 

Yep blast it.

 

pffluid2.jpg


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#13 Hook

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Posted 23 August 2019 - 02:14 AM

I've successfully soft soldered lots of nichrome wire.

However I prepared the wire ends by fusing a layer of  brazing rod to the ends first using suitable flux and an oxy-acetylene torch. Excess flux is removed before soft soldering.

The brass like layer can be easily soft soldered. 

I just wrapped the nichrome around the cable and soldered it. It was rock solid. The solder grabs the nichrome when it melts into and around the cable.


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#14 BGRE

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Posted 23 August 2019 - 03:00 AM

Did the solder actually wet the nichrome?

If not the joint will eventually fail.

 

Acid flux may work but acid flux residues will slowly eat the joint away and cause the joint to fail.

Acid flux is for plumbing not electrical work.


Edited by BGRE, 23 August 2019 - 03:01 AM.

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#15 Hook

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Posted 23 August 2019 - 07:00 AM

Did the solder actually wet the nichrome?

If not the joint will eventually fail.

 

Acid flux may work but acid flux residues will slowly eat the joint away and cause the joint to fail.

Acid flux is for plumbing not electrical work.

There's not many that will braze the ends of nichrome wire. My joint will not fail, and even if it did I would just re-join it, very simply done as I can pull out the strips, peel back the heat-shrink, and re-solder it. Sometimes people are put off doing things because someone wants to complicate it all. Science is great, but I prefer to rely on my experience and common sense.....that's not to say I know better than science, just  sticking to the method I have always used.....K.I.S.S.

Keep It Simple Stupid.

Most home diy'ers will not have access to brazing rods or an oxy-acet rig.



#16 don clement

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Posted 23 August 2019 - 11:04 AM

Just to complicate things IMO it would be a good idea to shield the inside of the plastic box with copper tape to prevent EMI from the switching regulators. https://www.amazon.c...ci-a=B01I1XNY1E  Also I use ferrite beads on power connections to prevent interference with sensitive devices like CCD cameras.    https://en.m.wikiped.../Ferrite_bead  

 

Don



#17 bobruben

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Posted 23 August 2019 - 01:09 PM

I sold lots of resistors when I worked the counter at an electronics supply company in days of yore. In high school, Mr. Krass, the physics teacher gave us a mnemonic he learned in the Navy. I won't repeat it here smile.gif . There is a cell phone app.

http://www.nothingla...esistorphotoid/ that gives you the value by using the camera.

 

I used seven 20 Ohm, 1/4 watt resistors soldered in series for dew control on my Telrad finder, hooked up to 12V, without a dew controller. One resistor is down by the lens, the rest chase around the outside edges of the glass plate. I also use a dew guard on the Telrad.

 

If you wanted to use a dew controller with Telrad resistors, you would need to use higher wattage, lower ohm resistors, my setup has ~1/7th of a watt per resistor. Watts = Volts squared divided by Ohms.



#18 Hook

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Posted 24 August 2019 - 02:17 AM

Just to complicate things IMO it would be a good idea to shield the inside of the plastic box with copper tape to prevent EMI from the switching regulators. https://www.amazon.c...ci-a=B01I1XNY1E  Also I use ferrite beads on power connections to prevent interference with sensitive devices like CCD cameras.    https://en.m.wikiped.../Ferrite_bead  

 

Don

Hey.......good idea, and it will prevent any alien craft from switching it off....lol.gif



#19 don clement

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Posted 24 August 2019 - 01:12 PM

Hey.......good idea, and it will prevent any alien craft from switching it off....lol.gif

The aliens might be trying to communicate thru hacking EMI messages to your CCD camera ;-) 

 

Don

 

Klaatu barada nikto


Edited by don clement, 24 August 2019 - 01:15 PM.


#20 Hook

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Posted 25 August 2019 - 05:47 AM

The aliens might be trying to communicate thru hacking EMI messages to your CCD camera ;-) 

 

Don

 

Klaatu barada nikto

lol.........funnily enough, while out looking through my scope last year with my son, we had a very strange encounter with an object in the sky. We were both so stunned all we could do was watch,.......and my camera and video camera was within spitting distance !




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