Quote:
Originally Posted by rcheshire
I used Nichrome in place of resistors using Al's sheet.
1333mm of 0.33mm Nichrome from Jaycar came in at 18.4R for my Canon 200mm prime lens. I double checked with an online Nichrome calculator. Commercial heaters typically use 0.75 watts per inch.
At 12v the heater can be handled. It's as warm as a freshly brewed hot beverage in bare hands.
Operating over 2 nights ambient down to 3C it worked flawlessly using an Arduino and logic level n channel MOSFET (low rds on) for switching. At the suggestion of an IIS member, I applied a dew point calc, as the heating control reference, polling a humidity/temperature sensor - a freetronics breakout board, again from Jaycar.
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Well done Rowland,
Do you have the model number or a link to the humidity/temp sensor?
If its as warm as a beverage, isn't it a bit too hot?
I've read that too much of heat can cause adverse issues
Heater straps, when you place them on your lips to feel the heat, are barely warm
I guess the heating over prolonged periods negates the need for too much heat
Cheers
Alistair