LED dimmer for Dew Controller

[billdan]

I want to make a 4 channel dew controller using LED PWM dimmers.

The picture I have attached will do the job, they are 12V to 24V input and can supply up to 8A of current (96Watts).

Now I can buy these off Ebay from China for about $5 ea, or get them through RS Components locally for $22 ea.

I would prefer just to buy the insides, as I will mount 4 of them inside a single box.

Does anyone know where you can just buy the PWM dimmer parts only without the cladding?

Cheers
Bill

[Weird1]

https://www.banggood.com/3-Channel-Dimmer-Adjust-Controller-For-RGB-35285050-Led-Strip-Light-Lamp-DC12V-p-1060557.html?rmmds=buy&cur_warehouse=CN

[iborg]

Hi Bill

Have you considered motor speed contollers?
https://www.ebay.com.au/itm/4000W-0-220V-AC-SCR-Electric-Voltage-Regulator-Motor-Speed-Controller-/322698407965?hash=item4b2252f01d

Philip

[redbeard]

+1

[billdan]

Thanks for those suggestions guys, the 3 channel controller may work however it seems to only provide less than 3A per output channel. I think I would need at least 4A for a dew heater (48Watts).

The motor controller looked exactly what I needed until I read it operates off AC voltages up to 240V. Do you know if you can drive it with 12V DC?

But I will do some more research on them and there may be a 12V version available.

Cheers
Bill

[Weird1]

Check out this video, its about using the PWM as a dew heater, it supposedly provides enough power per channel to run dew heaters.

https://www.youtube.com/watch?v=k3F5xwct8IE

Cheers Keith

[VPAstro]

I built mine out of the same ones you have pictured. I bought 3 of them off ebay from china. I then removed the casings and installed them inside a hobby box together with 1 fuse, one LED, one switch and RCA plug per channel.
I can switch them on or off individually and change the power output. All up cost about $20 for all the parts, and it works very well.
My dew heaters are just Nichrome wire between grey gaffer tape, some Velcro, speaker wire and and RCA plug. These also work very well, and only cost about $5.00 each to make.
Andrew...

[iborg]

Hi

Sorry, I didn't notice the voltage rating for that particular version.

There are others for 12V motors.

Philip

[redbeard]

Speed Controller 10A PWM DC Motor 12V-40V 13khz Control R9M3 U3W6
AU $3.76

Yep that one from ebay. I used to use these before I made an automatic one

[AndrewJ]

If you only want a simple manual PWM unit, you can make one yourself pretty simply using an LM324 chip and a few resistors/capacitors, and then select a MOSFET that will handle the power you want.
3 channels of the LM324 are used to make a sawtooth oscillator and the fourth channel becomes a comparator that compares the sawtooth to the potentiometer output to drive the MOSFET.
I have made quite a few this way and it only takes a few components.
The single channel one ( ref piccy ) can be made with a single LM324,
but if you add another LM324, you can make a 5 channel unit for virtually no extra work.
( That said, its still probably cheaper to buy something from China and repurpose it, but if you make it yourself, you can set the PWM freq and choose your own mosfets etc )

Andrew

[billdan]

Thanks everyone for your wisdom, Keith I enjoyed that video you linked to, although the gentlemans' soldering technique would not have passed the advanced soldering course I did at RMIT many years ago,

AndrewJ, thanks for your suggestion, I don't think I want to go right down to component level for this project, it would mean I would have to fire up my old Windows 98 PC and run Protel to design and then etch a Printed Circuit Board. Been there, done that.

It looks like I will have to import from China as the local suppliers just apply way too much markup on what they import.

I'll go down the path that Andrew (VPAstro) did and remove the cases from that LED dimmer I pictured and install them into a plastic box.

Cheers and thanks everyone
Bill

[VPAstro]

Bill,
When you get them, I can post some photos to show you how I set it up.
At the same time as purchasing the PWM's. I also bought 10 leds with leads for $1.00 delivered, the rocker switches and fuse holders. I think they were also about $1.00 delivered from China.
Thanks
Andrew...

[mswhin63]

Hi Bill,

Not sure if you had it figured out, but the AC unit will not work with DC. The triac (usually) requires an AC voltage to allow the AC signal to be re-instated when the dimmer is set.

DC would just either to be continuously switched on or off depending on the the state of the triac at the moment and would more than likely stay in that condition or do what it wants. Triac's generally get hot when switching DC.

[billdan]

Thanks for the advise Malcolm , I had figured it out the AC units would be no good at 12V DC.

Thanks for offer with the photo's Andrew, I'll send you a PM when they do arrive.

Cheers
Bil