Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

Dew probs

Coco

By Coco
in Discussions - Scopes / Whole setups

Recommended Posts

  • 3 weeks later...
Coco

Coco

Posted
  • Author
Posted

Thanks to Moonshane I bought 150 resisters for a princely some of £2.97 ...

Following Moonshanes link I set about making the strap..:icon_eek:

I used alloy angle and stretched out some scrap 1.0mm 15 amp wire, following the instructions I pinned the wire 5/8 (15mm)apart, then made a 5/8 (15mm) gauge and dotted the angle along its length, the rest was easy, I just placed the resisters along at equal distances and using a small gas soldering torch (admittedly most wont own one) ran the length dobbing each resister, the copper wire kept nice and hot so time on target was very brief...:evil6:

The end result was 64"" (1.4m) of heater strap for less than a £1, Ive still got 60 resisters left, I cut it into 2 pieces and tried 12v through it... works a treat!!... next step is insulating it.. :D

Total cost to me less than £3

2 x Dew heaters... one fits 8" newt the other a 4" frac

post-15416-133877516859_thumb.jpg

post-15416-133877516863_thumb.jpg

post-15416-133877516866_thumb.jpg

post-15416-13387751687_thumb.jpg

post-15416-133877516874_thumb.jpg

Link to comment
Share on other sites
Coco

Coco

Posted
  • Author
Posted
It would be easier to use Nichrome wire. It comes on bobbins varying restistance, measured in Ohms per metre,

Ron.

Interesting Ron... I enjoyed making the strap, would you know what length wire and what rating ? I'd like to have a go at it...:icon_eek:

edited... found it Doh!!

post-15416-133877517042_thumb.gif

Link to comment
Share on other sites
Coco

Coco

Posted
  • Author
Posted
excellent result matey. I must finish mine off. with a dew controller it really is perfect.

I am going to make a couple of Telrad ones too in the near future - also a plan for this on the link.

Yes it works a treat..... Nice and warm but not hot.... I need a dew controller now as i will forget to switch it off... :D

I wonder what sort of amp rating it is? :icon_eek:

Link to comment
Share on other sites
Moonshane

Moonshane

Posted
Posted

to calculate I am pretty sure it's V divided by R = A

so eg a 330 ohm resistors running at 12v would equal an amperage of 0.036A. for 10 resistors this would be 0.36A and for 10 running at 6v = 0.18A

assuming your 90 resistors used splits 60 and 30 they would draw no more than 2.5A and 1.25A approx (a bit added to be on the safe side) at 12v.

I am sure this is correct but someone will correct me if not.

Link to comment
Share on other sites
dmahon

dmahon

Posted
Posted
to calculate I am pretty sure it's V divided by R = A

so eg a 330 ohm resistors running at 12v would equal an amperage of 0.036A. for 10 resistors this would be 0.36A and for 10 running at 6v = 0.18A

assuming your 90 resistors used splits 60 and 30 they would draw no more than 2.5A and 1.25A approx (a bit added to be on the safe side) at 12v.

I am sure this is correct but someone will correct me if not.

For parallel resistors, I remember 1/Rt = 1/R1+1/R2+1/R3 etc

Therefore the total resistance (60 x 330 ohm resistors in parallel) would be 5.5 ohm and at 12v this means 2.18A

I think. But I haven't done physics for almost 20 years.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.