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Fan Controller PCB Layout

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SPASMODIC

New Member
Joined
Jan 30, 2013
Hi all... First time posting here. I'm in need of a fan controller for a hydroponic grow room I'm building. I stumbled across Bing's 7.5 Amp Adjustable Fan Controller. I have never learned to read a schematic let alone try to design a PCB from one. Just so happens I was crazy enough to try. Yes, I know I could just buy one, but where's the fun in that? ;)

I'll try to be as specific as I can about my needs as well as post as many pictures as I can. First, I'm wanting to use computer fans because they are a lot cheaper than in-line duct fans. I have three brand new 120mm's just sitting around for the last year anyway. Second, I don't need to move much air. Should never have to evacuate more that 200CFM. Being able to adjust fan speed will be sweet.

The Fans: (3) Rosewill DFS122512H DC 12V 0.4A 74.48 CFM 2000RPM
Fans are not PWM



They will be only moving free flowing air with passive inlet sized at 108 sq in. The Home Ventilating Institute recommends one square foot of open air inlet per 300 CFM of ventilation fan capacity.

OK, here is where I am at. I copied Bing's schematic into ExpressSCH. Imported that into ExpressPCB and got to work. I think I'm finished with the layout, but I'm hoping to get some feedback on the mistakes I have made before I try to etch my first board. Remember, this is my first time doing this... feel free to laugh :thup:

I sure hope Bing doesn't mind if I repost his schematic. I just thought it would help someone make sense of my Frankenstein...

Thanks in advance guys!!!
 

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Looks pretty solid for a first crack. Really the only things I have to mention are what I was told on my first crack, and what I've told everybody else too :D

I would make all the little traces wider, there aren't really and space concerns to worry about.
Along the same lines I'd use huuuuuuge traces for the power and ground lines to the fans. For three .4a fans what you have there should work fine, but it might be nice to have more room for expansion later.
The only remaining thing is that if you can fit them, T shapes work better for joining traces together than sharper y like angles. You'd already avoided 90* corners on single traces, which is excellent.
 
Looks pretty solid for a first crack. Really the only things I have to mention are what I was told on my first crack, and what I've told everybody else too :D

I would make all the little traces wider, there aren't really and space concerns to worry about.
Along the same lines I'd use huuuuuuge traces for the power and ground lines to the fans. For three .4a fans what you have there should work fine, but it might be nice to have more room for expansion later.
The only remaining thing is that if you can fit them, T shapes work better for joining traces together than sharper y like angles. You'd already avoided 90* corners on single traces, which is excellent.

Thank you Bobnova. I had been following the monster 2.5 yr long thread about a PWM controller. You guys are amazing. You gave me the confidence to give this a try. It's thanks to you guys I didn't completely butcher this layout. I hope soon to use arduino to control HID light schedule, temps, humidity all in one nice little package.
 
Glad we could be of service! The Arduino can definitely do all that, there should be completed projects and can copy parts of too. That always makes things easier :D
 
OK... Power and ground I bumped to 0.1". Looks like I may short at IC1 though. Small traces I bumped to 0.03" All "Y Connections" have been eliminated... I think! Since this isn't going into a computer, I decided to use a 3 pin connector for power. I have an old 12v 1.7a wall-wart that I will solder and sleeve to and old fan connector. I think I should be able to pull 3-4 amps through that connector. Again, thank you so much!!!
 

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That looks good to me. Standard fan headers aren't rated especially high, but they should be good enough for that. I've had one die on me but that was on a 4.4 amp fan.
Do be sure to test the wallwart and make sure it actually puts out 12v under no/light loads. If it's the heavy transformer type it may put out more like 17v with a light load!
 
That looks good to me. Standard fan headers aren't rated especially high, but they should be good enough for that. I've had one die on me but that was on a 4.4 amp fan.
Do be sure to test the wallwart and make sure it actually puts out 12v under no/light loads. If it's the heavy transformer type it may put out more like 17v with a light load!

Thank you, I'll check that out, gives me an excuse to bust out the dmm. No scope to play with. Wouldn't know how to use it anyway... lol

Well, I guess I'll order quadruple the parts I need and try to follow the Youtube video on how to etch this board.

BTW, did you happen to see Vin and Vout on the IC1? I'm sure they will touch. I don't think my free program will let me adjust the size of the pad, unless I ungroup/regroup it and fix it that way. Actually, I'll stop pestering you and give it a whack...
 
You can use a screwdriver to a dremel to scrape the trace so they don't connect if it turns out to be an issue.
Not pretty persay, or exactly the right way to do it, but it would work fine :D
 
You can use a screwdriver to a dremel to scrape the trace so they don't connect if it turns out to be an issue.
Not pretty persay, or exactly the right way to do it, but it would work fine :D

Figured it out. Just used a ground plane around the connection. Looks almost professional... lol

Woo... Hoo... :attn:
 

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