I bought some Nichrome wire today at Jaycar in Ballarat to hopefully make dew heaters for my ED80 and 100mm guidescope.
I have read about 15 websites today and read the posts in here about how to make it work and I am now more confused than before I started reading.
Some sites say just connect the Nichrome wire to a 12v power supply, others say I have to use a Pulse Wave Generator (whatever that is). Otheres say do not use a Potentiometer, others say use one.
I am very confused.
I'll tell you what I DO have so one of you might be able to help me:
I have an Apple PC power supply (13.5v, 1.0Amp, 15VA) and 4 metres of RES80 Nichrome wire.
What I want to do is heat both the ED80 and the 100mm Guidescope.
I won't be going back into Ballarat for quite some time so I am hoping I can build my unit without having to go buy more bits.
I know I have to cut the wire to length, but do I really need all the electronic gizmos to make it work?
Any help would be appreciated
P.S. I also bought Cloth Gaffer tape to house the wire in, and some sticky-backed Velcro tape to mount it.
My heater is simply the Nichrome wire trimmed to the right length attached directly to a 16v AC power supply. Works like a dream. I don't have it infront of me now, but I'm pretty darn sure there's not even a resistor in-line, let alone a matter to anti-matter converter or something! (what'd you say, Pulse Wave Generator?? - sounds like a warp engine). I would like a variable resistor inline to tune it's heat.
Oh, and what "the right length" is, I don't know sorry - it comes down to how hot you want it - the longer the length for the same input voltage & amperage, the colder it is. So you will need someone to pop up and explain how long it should be. My cousin worked it out for me, he's knowledgeable in such things. If you don't get help, I can ask him. I think it's a pretty simple case of dividing the resistance of the wire in to the output of the 16v power pack, or something like that...
Oh, and what "the right length" is, I don't know sorry - it comes down to how hot you want it - the longer the length for the same input voltage & amperage, the colder it is. So you will need someone to pop up and explain how long it should be. My cousin worked it out for me, he's knowledgeable in such things. If you don't get help, I can ask him. I think it's a pretty simple case of dividing the resistance of the wire in to the output of the 16v power pack, or something like that...
I can work out the length, that's not the problem. Laurie (RAJAH) mentioned how in one of his old posts.
The problem was 'do I need all the do-hickeys' or can it be directly wired to the power supply, but you have answered that. You do it, so it must work
Oh, I looked up what a Pulse Wave Generator is. It works better than a potentiometer. A pot sucks some of the power making it like a resister, whereas a PWG doesn't. It turns the power on and off according to how you set it.
Now we both know
I'll give the power supply a try and see how I go, thanks Roger
My FSQ (tube 106mm) uses about 18 ohms and my FS-60c (tube 60mm) uses 28 ohms. You must insulate the outer surface to ensure you don't lose too much heat outwards. I don't bother with PWM stuff. I know it makes great sense, but I have got by without it so far - 8 years now. A modest, constant temp is perfect.
If you are interested to know more PM me and I will give you the details on how to do it. Seriously, it is really cheap and very efective.
At 1 metre is was very hot. Almost too hot to touch. At 1300mm it was only just slightly warm to touch. Big difference for such a small change of only 300mm in length!!!!
How warm should it feel to the touch in your hands? Only barely noticable, or slightly warm?
Oi sunshine, was that on the scope or free air, sheesh, that makes ALL the difference ;-). Whilst on the ota, its should feel a bit warmer, not scorchingly hot!.
Oi sunshine, was that on the scope or free air, sheesh, that makes ALL the difference ;-). Whilst on the ota, its should feel a bit warmer, not scorchingly hot!.
Just laying the wire along my kitchen bench, not outside.
Looks like I'll have to run them on seperate lines from the power supply as I can't work out a way to run the wires in Parallel.
Nah, your not that thick hehe. Run a pair of wires to the scope, then connect all the heaters to the supply pair, easy. No need for seperate supply wires. Cant work it out?, whaaa, plus and minus to the heaters, each connected to these wires, what dont you understand about parrallel?.
Good grief, thats pretty ;-). Use the middle pic and just connect the 2 blue loops together at the same point as the top loop. The current draw for my 12" with a kendrick was about 3A and less than 2A for the ED80, so with fairly modest speaker cable, it would easily carry the 5 amp total. There is really no need to run seperate supplies for each.
