How to to PWM control a 4-pin fan? (solved) - Page 1
Forum section: electronics / beginners

author: vgamesx2
author_rank: Regular Contributor
timestamp: August 12, 2015, 03:24:47 am
content: Hello, can someone help explain how to to PWM control a fan with built in PWM, I understand the idea behind how PWM works, what I don't understand is how to provide a separate 5v/3.3v signal to 4-pin PWM fan.Which in my case the datasheet says it will take 0v-15v PWM so that's less of an issue, though I still don't understand how to wire it, would it be as simple as wiring the pwm signal to the fan and the negative to the same ground/negative as the power line?Here's the datasheet if you want to take a look.http://partner.delta-corp.com/Products/FANUploads/Specification/PFC0812DE-SP04.pdf

author: retrolefty
author_rank: Super Contributor
timestamp: August 12, 2015, 03:35:40 am
content: As I read the datasheet the PWM signal can be a low as 2.8vdc for a HIGH and still function within specs. So as long as you have a common ground connection to a micro you should be able to drive it with a PWM output pin. Might be marginal with a 3.3vdc micro, but a 5vdc micro should have no problem.

author: vgamesx2
author_rank: Regular Contributor
timestamp: August 12, 2015, 03:46:28 am
content: Do you have a suggestion on what I should use then? If not that's fine I'll keep looking.Thanks.

author: retrolefty
author_rank: Super Contributor
timestamp: August 12, 2015, 10:24:10 am
content: Your question is too broad. You could explain what you are trying to accomplish, automatic temperature control? Manual control with a pot? A simple arduino could allow you to test the fan, but how and what you are trying to accomplish needs a better explanation.

author: vgamesx2
author_rank: Regular Contributor
timestamp: August 12, 2015, 06:39:57 pm
content: oh right, sorry about that.. I'm basically using that high powered fan to make a fume extractor, so manual pot control since I don't want it running at full speed all the time, I tried using current control which worked but my buck converter was either a dud or really didn't like that, so I suppose I'll do it the proper way... Lol

author: SirWhy
author_rank: Contributor
timestamp: August 12, 2015, 08:17:46 pm
content: A small microcontroller, such as an attiny45, would be a good way to manage the PWM signal.Have the micro read in an analog value from the pot, and output a pwm waveform accordingy. If you have an arduino, it'll be easy to program the attiny45 as well.

author: dadler
author_rank: Unknown
timestamp: August 12, 2015, 09:50:25 pm
content: Or a 555:http://www.dprg.org/tutorials/2005-11a/

author: kizzap
author_rank: Unknown
timestamp: August 12, 2015, 10:11:18 pm
content: Quote from: dadler on August 12, 2015, 09:50:25 pmI did something quite similar, which worked a treat:https://www.dropbox.com/s/ofirymtayz2dbud/DC_Load_Fan_PWM.pdf?dl=0

author: vgamesx2
author_rank: Regular Contributor
timestamp: August 12, 2015, 10:45:21 pm
content: Quote from: SirWhy on August 12, 2015, 08:17:46 pmI unfortunately don't have an arduino, though I'd like to get a clone or two just to play with.Quote from: dadler on August 12, 2015, 09:50:25 pmI sorta thought about that though instead, what about something such as this?http://r.ebay.com/gEs2tmI would actually kinda prefer something pre-built just to keep things simple, also the pic in the description actually helped me understand how the signal wire works, I thought I would need a PWM signal as the positive and connect the gnd/neg elsewhere, I didn't realize you could just have power input and PWM output like that.Quote from: kizzap on August 12, 2015, 10:11:18 pmNeat

author: SirWhy
author_rank: Contributor
timestamp: August 12, 2015, 11:57:47 pm
content: Quote from: vgamesx2 on August 12, 2015, 10:45:21 pmConsidering that it's a prebuilt module of the 555 PWM circuit it would work perfectly. I'd still recommend building the circuit up yourself at some point though just for fun/experience. I believe Dave did a video about it as well, but can't link it right now.

author: vgamesx2
author_rank: Regular Contributor
timestamp: August 13, 2015, 12:10:59 am
content: Quote from: SirWhy on August 12, 2015, 11:57:47 pmYeah at some I'll definitely delve deeper at some point, for the moment though I'd probably botch it up Lol and depending on how, it could be costly to fix (as in I might kill my fan), so later on I'll get a cheap fan $3 fan off ebay to try it with instead.