Really easy to make arduino dew heater controller

[Corpze (Daniel)]

Hi again.
I recieved two new boards (4ch irf540) but both of them puts out 12v regardless if the respective channel is activated by the arduino or not (the led on the 4ch mosfet board is only shining when the arduino output is activated by the code ( as it should be)

But even if the output from the arduino is 0% and the LED on the mosfet board is dark, it is 12v to the heater band and it gets really hot.

My connections is correct on the low-level side, as the LED is on or off when the arduino activates the output.

The 12v side is connected as 12v+ in and ground (shared ground with the arduino)

The outputs are connected 12v+ and ground from each channel to a RCA connector with same ground as the casing (and arduino)

I just can't seem to understand why the mosfet is always on?

[ChrisV (Chris)]

After a long break I've made many modifications to the dew heater. Its now a simple stand alone unit but can also be controlled via USB on a PC to monitor it and change mode/settings. The basic Arduino coding and .exe are here

https://drive.google.com/drive/folde...gR?usp=sharing

Might take a few days to re-write all the instructions

[inertia8 (Australia)]

Just wanted to say, excellent work!

Shall be building one of these after deciding upon which screen to use.

[ChrisV (Chris)]

Inertia8

I don't use a screen anymore. Makes construction simpler and frankly it was just one extra thing that could go bung. I made a PC app that sets it all up. You can then just let the box run and do its own thing; one less thing to think about while imaging. Or you can have it connected to a PC to see what's going on, or change settings. I also redid the feedback controller; uses PID and is much better. This is also good cause it greatly reduces power consumption!

Instructions should all be on the Google drive link with my last post. But I will go through and check, and add some photos of new build. But any questions reply in the thread or PM me.

[inertia8 (Australia)]

Cheers Chris.

Mines actually for a 10in dob and visual observing.
I had severe dew last weekend and had my observing cut short. Telrad and finder dew up, then secondary. Primary looked horrible but it does under red torch...

At a minimum I'm doing it for telrad, ep and eyepiece. Figured I would do the secondary but that looks tricky with the thin foil on one spider for wiring.

I would prefer a screen just to confirm what's going on etc. can the little oled be dimmed right down?

[ChrisV (Chris)]

The OLED. I just put some red translucent plastic sheet over it. Dimmed it and kept the dew out!!

[inertia8 (Australia)]

Excellent, I've done a bunch of ordering from Ali.. along with the kit to try and repair a fried Goto board or two..