Dew heater help C:

[platt.michae18]

I guys, thanks for stopping by and reading.
Im making my first Dew heater. I have 2 dozen 330ohm resistors and 2 30cm long copper cable to make my ladder, and I was just wondering how much space should I put between each resistor??
It has to cover 205mm or 21cm (rounded) to add velcro.

Thanks guys!

Michael

[StuTodd]

Hi Michael.

Not answering your question directly, but it is far easier to make a dew strap with nichrome wire rather than a ladder of resistors.

I have made many in less than 10 minutes and the wire is cheap too.
For calculations and explanation (including a great excel worksheet) see
http://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater.html

Sorry if this isn't answering your original question, just hope it helps a bit?

Stu

[platt.michae18]

Thanks! ill give it a go!

Michael

[StuTodd]

Awesome Michael.

Dont forget http://www.ebay.com/itm/12V-Adjustable-Controller-LED-Dimmer-Switch-For-Dimmable-Light-Bulb-Lamp-/222242230993?hash=item33beab52d1:g: dV0AAOSwFe5Xz8YX to control it with.

Couldn't be simpler. + and - 12vdc cigarette plug wires in, and the + and - wires out to an audio jack plug.

[ChrisV]

+1 nichrome. Real easy. A few rounds in parallel and series as per the calcs mentioned. Cover in the thinnest heat shrink to stop parts shorting out. Lay on gaffatape. Doesn't solder well so twist around connecting wire and solder to hold together. Then put heat.shrink over that also to hold it together. If you want to improve heat conduction to the scope you can put adhesive aluminium tape on one side. Can get all the stuff from jay car and that large home improvements chain.

[platt.michae18]

Sorry for the late reply!!!
I sorta forgot about the post :P

Im currently on the look out for some Nichrome wire.
I'm still a little confused by the spreadsheet, but ill get it eventually.
Thanks for all the help!

[StuTodd]

Another tip,
Wrap the end of your length of nichrome wire onto a nail in a wall, the other end in a drill chuck. Give it a spin for a few seconds and you'll be able to put the whole length of wire through the heat shrink no probs :thumbsup:

Stu

[ChrisV]

The drill sounds fun. To straighten it I pull it tight and run it quickly over the gas stove to make it red hot.