Go Back   IceInSpace > Equipment > ATM and DIY Projects

Reply
 
Thread Tools Rate Thread
  #1  
Old 02-02-2021, 01:42 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
DIY, making a low power lens dew heater

I bought two new dew heaters. They are sold to be used on camera lenses and powered from USB. I have modified them to reduce the power from 8 Watt to 2 Watt which will be enough for my demand.

Some photos and documentation from this project:
http://www.astrofriend.eu/astronomy/...ting-band.html

This will be battery operated and I try to reduce the power consumtion of the equipment.

/Lars
Reply With Quote
  #2  
Old 03-02-2021, 03:55 PM
Saturnine (Jeff)
Registered User

Saturnine is offline
 
Join Date: Jul 2008
Location: Wollongong
Posts: 2,134
Excellent little project, well done. Very neat and tidy in the end and the desired output.
Reply With Quote
  #3  
Old 09-02-2021, 07:10 PM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Hi Jeff,
Thanks for the comment. I have now tested the dew heater a couples of nights and it work perfect. Maybe I even can reduce the power even more from the 2 Watt I have now. My shortest lenses, th 16 mm fisheye and the 50mm f/1.8 lens I know from earlier only need about 1 Watt.

/Lars
Reply With Quote
  #4  
Old 09-02-2021, 08:18 PM
Rerouter's Avatar
Rerouter (Ryan)
Registered User

Rerouter is offline
 
Join Date: Jan 2021
Location: Sydney
Posts: 117
Edited

Now I get it, its a DC-DC converter powering all the USB stuff,

So about 3.1 Ohms per Dew heater, ~1.6 Amp on 5V,

For 1W per heater, you would need 4 in series, 2 per scope, might be easier to replace the wire with 1m of AWG40 magnet wire per heater for series. or 4m for parrellel, which would not actually be hard to just sew into a dew heater fabric

Last edited by Rerouter; 09-02-2021 at 08:47 PM.
Reply With Quote
  #5  
Old 09-02-2021, 08:44 PM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
yes it's correct, 3.1 ohm, before I cut the cables length it was 3.4 ohm. But because they are connect in serial of each other the voltage over each is only 2.5 Volt. It gives 2 Watt each. U^2/R = P.

If I want to have lower power I have to use the included regulator, it's like a very slow pulse width modulated device. With that I can have the 1/1, 1/2 or 1/4 setting, the last should give about 1/2 Watt at each heating band.

What power do you have on your heating devices and to what lens or telescope ?

/Lars
Reply With Quote
  #6  
Old 09-02-2021, 08:53 PM
Rerouter's Avatar
Rerouter (Ryan)
Registered User

Rerouter is offline
 
Join Date: Jan 2021
Location: Sydney
Posts: 117
As I have not yet gotten my confidence up to image away from home, right now I have a zip tied coil of wire running off the same lab power supply I am using as a temporary intervalometer (could not get more unconventional)
Reply With Quote
  #7  
Old 10-01-2022, 09:10 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
I have now used my new USB dew heater out in the cold night several times. Many positive things, I can reduce the power a lot. From my earlier dew heaters at 5.6 Watt I can now go as low as 1 Watt for both. Important when out on the fields and on battery.

Photos and text:

http://www.astrofriend.eu/astronomy/...ting-band.html

/Lars
Reply With Quote
  #8  
Old 10-01-2022, 09:26 AM
AdamJL
Registered User

AdamJL is offline
 
Join Date: Sep 2010
Posts: 2,100
Nicely done, Lars!! That looks really neat now.
Nothing better than good cable management
Reply With Quote
  #9  
Old 12-01-2022, 06:16 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Yes, cables everywhere cause trouble in the dark.

These dew heaters were an important step towards the mobile observatory. With lower current, smaller battery.

Today I orderad a 24 Volts Lithium battery for my new project. I come back about that in a new thread later. 24 Volts an 12 Amph, about 300 Wh. My lead car batteries: 12 Volts and 45 Amph gives about 500 Wh but can't even use half of it, the other 12 Volt and 72 Amph gives 850 Wh. Both batteries are now destroyd because I let them uncharge too deep.

/Lars
Reply With Quote
  #10  
Old 12-01-2022, 11:08 AM
AdamJL
Registered User

AdamJL is offline
 
Join Date: Sep 2010
Posts: 2,100
Agreed, Lars.
Many folk still use lead acid batteries, but if I were buying now, I'd buy Lithium. Too many benefits, not enough downsides. They're fantastic batteries.
Reply With Quote
  #11  
Old 12-01-2022, 03:58 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
You could reduce power usage even more with feedback PWM control to set heater temp just above dew point. Then you are only using enough power to stop the mist.
Reply With Quote
  #12  
Old 12-01-2022, 09:35 PM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Yes, I have some thoughts to control the dew power direct from the Raspberry. I just need some dew point sensor. Do you have any idea how to design that kind of sensor ?

/Lars
Reply With Quote
  #13  
Old 14-01-2022, 09:36 AM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
There's several really good humidity/temp sensors and dew point is simple to calculate. This is my design, and others on IIS have some nice ones.
https://www.iceinspace.com.au/forum/...d.php?t=144679
Reply With Quote
  #14  
Old 16-01-2022, 08:21 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Hi Chris,
Thank you for posting that. I have thoughts about Arduino and to control the focus motor, when I can handle that I take a look of a dew heater controller too.

I have the USB-Focuser now, it can also be delivered with a dew heater. But not interesting if I built my own focuser controller and then I have much better control over the system.

Maybe you already have a Aurdino focus motor controller ?

/Lars
Reply With Quote
  #15  
Old 16-01-2022, 08:39 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
I have built focus controllers. But I haven't gone to the effort of the software. There's really good stuff out there! E.g. myfocuserPro and onstep software. And they have ascom drivers!
Reply With Quote
  #16  
Old 17-01-2022, 12:05 AM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Hi Chris,
Sounds perfect, are there also Indi drivers available ?

/Lars
Reply With Quote
  #17  
Old 17-01-2022, 05:39 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
Definitely is for myfocuserPro
Reply With Quote
  #18  
Old 09-02-2022, 03:37 PM
mura_gadi's Avatar
mura_gadi (Steve)
SpeakingB4Thinking

mura_gadi is offline
 
Join Date: Apr 2019
Location: Canberra
Posts: 829
Aluminium Ion batteries are very close now, should be in production by end of year. But Covid has changed a lot of dates....

Al-ion is safe, you can swallow them!, they won't catch on fire, they hold more charge and allow for more recharges than li-ion by several factors.

It may be worthwhile just getting by on what you need and wait for way better safer tech later this year/early next.


MG
https://www.forbes.com/sites/michael...h=85ba11a12ebd

I think I read somewhere is was car batteries and the penny batteries. The other batteries will follow along after them...

Last edited by mura_gadi; 09-02-2022 at 03:50 PM.
Reply With Quote
  #19  
Old 20-02-2022, 09:44 PM
Astrofriend's Avatar
Astrofriend (Lars)
Registered User

Astrofriend is offline
 
Join Date: Aug 2017
Location: Stockholm, Sweden
Posts: 439
Yes, aluminum batteries are really exiting. I hope we have them here soon or later. But already what I have now is a big improvement.

/Lars
Reply With Quote
  #20  
Old 18-03-2022, 03:09 PM
joshman's Avatar
joshman (Josh)
Registered User

joshman is offline
 
Join Date: Aug 2007
Location: Coffs Harbour, Australia
Posts: 615
Quote:
Originally Posted by ChrisV View Post
There's several really good humidity/temp sensors and dew point is simple to calculate. This is my design, and others on IIS have some nice ones.
https://www.iceinspace.com.au/forum/...d.php?t=144679
I've been using your design for a few years now, and it's been absolutely fantastic. I'm currently in the process of making my version smaller and soldering it all down to a PCB in a 3d printed enclosure, and running 4 power outputs as well, so i can run everything off the one box.

so Thank you!
Reply With Quote
Reply

Bookmarks

Tags
dew heater, diy

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 01:48 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement