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 Helmet Fans, but with variable speed.

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Helmet Fans, but with variable speed.
« on: Apr 29, 2020, 05:55 PM »
There are so many great helmet fan kits, and it's a super simple and very cheap mod to add to your bucket list.

Most variants I see are USB powered with an on/off switch, so I figured I'd take it a step further and add a variable speed control to the mix (yes with future support for wireless gauntlet control).

The unit I ended up making, shown below, has Micro USB in for power, JST plug for a fan, and a single pushbutton. The idea is, this mounts under the rim of your helmet, so you can access the button with a pinch.

Click to cycle through Max -> high -> medium -> low -> off. Double click to go straight to max. Push and hold for off. Simple.





Technically, this is a general purpose Pulse Width Modulation circuit, built around a tiny microcontroller, that can be reprogrammed to do a lot of things. Output switches an N-channel mosfet, capable of sinking around an amp of current.

This little nugget of goodness can be used for handling lighting effects in props as well, since it's basically an Arduino light dimming circuit.

Controlling Fans with PWM?

Education bits: Pulse width modulation is turning the power on and off really quick, to create the illusion of a lower voltage / brightness / speed. This comes up a lot in LED based circuits, since LEDs usually can't be dimmed through a full range by varying the voltage alone (at a certain point they simply don't glow anymore).

Most of those 5015 round blower fans you put in your helmets run on 5 volts, and you can turn that down to about 4 or so before they cut out. Even at the lowest voltage, they're still running pretty loud.

Some fans, like the ones in your computer or laptop, have a third or fourth wire for PWM control, which control the speed through internal circuitry. Those would be ideal to use here, but don't have a useful form factor, and the price is a bit high.

If we directly feed a 5V brushless DC fan a standard Arduino-esque PWM signal (~450 or ~900 Hz), well hear an audible whine but nothing will move. To solve this, we feed it a PWM signal with a much lower carrier frequency. For this project, I use 50Hz.

At that speed, it gives the fan periodic nudges to get it spinning again, then lets it coast, then nudges it again, 50-60 times per second. This is enough to keep the fan moving at low speeds, without causing an annoying whine. As a trade-off, you get a ticking sound when the motor engages.

To reduce the ticking sound, I added some additional circuitry to the board, specifically a capacitor on the base of the Mosfet, which rounds our the voltage spike engaging the fan for a slightly softer start.

The end result is a pretty efficient (18 or so hours on a budget USB power bank) helmet fan, which can provide a full force gale or gentle breeze to keep air moving, controllable with a single button press, and only gently ticky at the lower speeds.

Without fighting the internal stator control circuit on these fans, this ain't bad for the price to make them.


What do you think? Neat?






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Fi-8015


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Re: Helmet Fans, but with variable speed.
« Reply #1 on: Apr 30, 2020, 12:56 AM »
That's great! I always wanted to add a speed control like that to my 12 V fans.

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electriFi - Mando Electronics English / German
Re: Helmet Fans, but with variable speed.
« Reply #2 on: Apr 30, 2020, 10:34 AM »
That's great! I always wanted to add a speed control like that to my 12 V fans.

How are you powering your fans? I was considering tinkering with the higher voltage fans to see if there are any benefits to running those over a 5v set.

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Re: Helmet Fans, but with variable speed.
« Reply #3 on: Apr 30, 2020, 11:19 AM »
The airflow is much higher and so is the noise level. A hearing aid is recommended. I use the fans in combination with an adjustable voltage booster with micro USB socket. I set them to 10 V which is enough in my oppinion, but an easy way to control the speed would be great (you always need a screwdriver to adjust the voltage). And it's neccessary to have some extra powerbanks, if you are using the small ones.

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electriFi - Mando Electronics English / German
Re: Helmet Fans, but with variable speed.
« Reply #4 on: Apr 30, 2020, 12:11 PM »
The airflow is much higher and so is the noise level. A hearing aid is recommended. I use the fans in combination with an adjustable voltage booster with micro USB socket. I set them to 10 V which is enough in my oppinion

Hmm... I might grab a set of 12V and 9V fans and see what I can do with this. I wish I had a decent way to compare air flow... maybe a tube and a ping pong ball, yeah! The fact that the fans are tolerant of 10V is a good sign. I mentioned it earlier, but with the 5V fans there is a small region for adjusting voltage before they cut out entirely, which is why this circuit came about.

If the 12V fans prove more efficient in terms of power use vs. airflow, that'd be great. I suspect, however, that they'll rattle a bit more at the lower speeds on this controller. For science!

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Ori Dart


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Re: Helmet Fans, but with variable speed.
« Reply #5 on: Apr 30, 2020, 02:39 PM »
Pardon the pun, but this is super cool. I might have to hit you up for a few of these units as I'm gonna need ventilation for my mando pilot, a Tie Pilot I'm building and maybe even for my new Scout helmet.

I'm really looking forward to seeing this as a gauntlet-mounted control. That would be perfect. If you got a small enough radio or Bluetooth module, I'm sure it could fit.

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Re: Helmet Fans, but with variable speed.
« Reply #6 on: Apr 30, 2020, 03:10 PM »
I'm really looking forward to seeing this as a gauntlet-mounted control. That would be perfect. If you got a small enough radio or Bluetooth module, I'm sure it could fit.

Yeah! I'm going to add a place for the radio on the back of the next revision of these boards, and a general purpose transmitter board that you can mount into whatever gauntlet / prop you happen to have (some soldering required, perhaps...)

These boards right now are 3/4" x 1 3/8", with not a whole lot of extra bulk added from the case. The 2-fan version (5-9v fans) is only a little bit wider. I like making things small, but not unreasonable.

I might start a listing in the appropriate marketplace forum for these, right now they're up on Etsy but that's an offsite link, which I've seen is frowned on.

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Kurz


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Re: Helmet Fans, but with variable speed.
« Reply #7 on: Apr 30, 2020, 04:11 PM »
Can you please stop making awesome stuff thet I want to buy as I see? :laugh:

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Re: Helmet Fans, but with variable speed.
« Reply #8 on: May 01, 2020, 07:16 PM »
Looks like the 12 volt fans arrived, so the fun can now commence. For SCIENCE!

Also, I posted a sales thread over in the trading area: http://mandalorianmercs.org/forum/index.php?topic=190272.msg2123914#msg2123914


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Re: Helmet Fans, but with variable speed.
« Reply #9 on: May 01, 2020, 10:33 PM »
Cool,I made a circuit for a friend's royal guard,it was PWM too but the speed was adjusted with a potentiometer and it was for a 12V fan.I'd love to buy one for my bucket but sadly I can't order stuff online. :porg1:

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Re: Helmet Fans, but with variable speed.
« Reply #10 on: May 02, 2020, 11:00 PM »
Two fans are twice as good as one fan.
12 Volt Edition



So a couple days ago I mentioned I was going to check out the 12V fans, and they came in. The air flow is a little stronger than the 5V fans, as expected, but they have an interesting and much broader allowance for speed control. I can get them to run at the same low speed the 5V fans run at, and they run just a little bit smoother.

The single-fan circuit is stuck at 5V, so the 12V fans only work on my dual fan circuit, which has a regulator to power the control circuit off of whatever reasonable voltage you feed your fans. I tried, for science, using this to run 5V fans off a 9V supply, something which will be possible in the next run when I get rid of the linear regulator and add a boost/buck switch mode converter.

That said--I'm going to do a run for the second iteration of the dual-fan module IF I sell a few of the 5V single or 12V dual modules. The second iteration will be able to power 12V fans from a USB lead, or 5V fans from a higher voltage source (I'd say 9V batteries but they actually have a pretty bad capacity for their size). This next version will also have independent output control for doing 1 fan 1 light combo, etc.

And, still working on the wireless. I want to get rid of some of these sets right now before I start a new project.

The 12V 2-fan systems are also on the trading station: http://mandalorianmercs.org/forum/index.php?topic=190272.0#post_MT-CF3K2

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Re: Helmet Fans, but with variable speed.
« Reply #11 on: May 12, 2020, 08:57 AM »
I picked up a wireless remote switch, that I was was going to mount in a vambrace , would that work on the 5v system?

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Re: Helmet Fans, but with variable speed.
« Reply #12 on: May 13, 2020, 02:07 AM »
I picked up a wireless remote switch, that I was was going to mount in a vambrace , would that work on the 5v system?

It depends, do you have a link to the remote system you picked up?  I can check it out and see if it can be made to work somehow.

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Re: Helmet Fans, but with variable speed.
« Reply #13 on: May 13, 2020, 11:15 AM »
Hmmm, let me check and get back to ya.

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