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Old 18-09-2020, 07:14 PM
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RyanJones is offline
Join Date: Jun 2018
Location: Melbourne,Australia
Posts: 1,117
Thank you everyone .

Steve and greg. The Arduino version does look like a great option but I really wanted something I could do all by myself which certainly at this stage ruled out anything that needed programming. It certainly would have given me more options for control though. I did enjoy the challenge of trying to incorporate auto temp control into the system though.

Wilco, sounds like itís made the same way as Ben did. I bought 3 PMW motor/LED controller kits from Jaycar. I started by making a small dew strap using some resistors to use to test it. This required some calculations to create a strap that produced about 5W at full power (12v). I think overall resistance was somewhere around 25ohms. I built the PWM kits and wired up the Potentiometer remotely. I used the strap and tested it and it worked. Next was to integrate temperature control. I bought some thermistors that were about half the resistance of the potentiometers (47kohm). I wired them in between one leg of the potentiometer and the board so that the temperature dictated a percentage of the high/low timing of the pulse width. I mounted them to a prototype pcb and fitted into one end of the box with an exterior fan blowing onto them from outside the box. When it came to the screen, that wasnít my orginal intention. I actually wanted to have individual LED bar graphs for each channel. The problem was the IC to run the LEDs requires an analog voltage and the PWM output is just pulsing 12v so they didnít work. I looked into making a low-pass filter to smooth the voltage out but it stated to get to complicated for my little brain and stared to test my patience. In the end, I think Iím happier with the screen. I think it gives it more of a professional look. Iíve made a secondary heater to use with it already. See image below although this isnít the finished version and the finished one has a lot more resistors. Iíve tested that with it and it works perfectly so just quietly Iím quite a happy chappy. This weekend I hope to make my guide scope heater and then test it with 2 loads.

Thanks again for the interest and positive comments

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