Using a soft start circuit on two fans for solder fume extraction.
HTML-код
- Опубликовано: 20 фев 2024
- Each video I will grab a random electronic component from the vault and build a circuit - this week I disappear during Tay Tay mania and rework my old PC Fan / Solder Fume remover. What's better than one free fan? Two fans working together to keep me safe!
Skip to bloopers and final wrap-up:
• Using a soft start cir...
More info at onecircuit.blogspot.com/2024/...
www.tindie.com/stores/bovineck 
Наука
I laughed when you pulled out the pink tiny calculator 😂
Visual puns are the best - although it was also funny when the Gordon Setter tried to jump up on the bench! 😂
Good video.
Computer fan tachometer output is an open collector, so just pull this up to voltage you need and you will see nice and neat square waves, usually 2 per revolution.
Wow! I could not find that info anywhere. To the bench! 👍😀
@Xaelloss. Yep, found this out when I repurposed an old HP workstation motherboard and needed to fool it into thinking all the fans were plugged in. One astable 555 timer circuit at ~1.6Khz and the BIOS reported fan speed at ~790 rpm.
When testing the tacho signal from the fan I got nothing on the oscilloscope, the corresponding pin on the motherboard header showed 5V. So, on my test circuit, a pull up resistor to 5V (I used 10kΩ) attached to the yellow wire and presto.. a square wave. You obviously don't need the pullup when the fan is plugged into the motherboard. After all that's how it's supposed to work.
Its read by the bios so its probably some type of one wire serial. Very common circuit.
Nice workbench!
Ah Computer Trader on Liverpool Street that well known London Underground station!
👍
Iconic! 👍😀
A resistor in series will slow it down. If it burns then itll go open circuit and stop haha
Thanks for the video! Two things that I noted... The insulation on the orange wire on the bottom of the perf board looks as if the wire is burned up. If so, that adds a lot of resistance. On the power input side of the LM317, you have only added the 0.1uf required by the regulator, itself. As you are powering motors, I would think that you need to add a smoothing cap. I wonder, if that cap would help the second fan to start correctly...
Excellent powers of observation! I did look at replacing that wire - but then I knew that pretty soon I would design a PCB and eliminate all that hasty/nasty wiring. It was a bit of rush job in the end and the wire got in the way a couple of times of the soldering iron. Good tip on the input cap as well - I'll do that in the final design. 👍😀
A fan will always have the largest surface to suck from, because you can't suck more air than the surface, but you can blow. So, the pins that hold the fan motor is always the side it will blow out from. Hold you hand on the suck side and you will hear the fan spin faster and that is because it will suck less air. If you do the same on the blow side it will still suck the same amount of air, but the air will get a higher speed around your hand.
Interesting! Thanks! 👍😀
You could eat off that bench compared to mine haha
It’s been a lot worse. 😬
if you were to position the circuit above the fan you wouldnt need a heatsink on the LM317😂
Brilliant! 👍😀
The yellow line is literally just a pulse for each rotation. The computer detects that to know the speed of the fan. The computer gives the fan a variable voltage supply to change the speed. Yellow is just a feedback pulse.
Hell of a signal to decode. I was hoping it was a speed control line, not a speed output line. 🤷🏻♂️👍😀
It was pretty messy! But, free fans are free for a reason 😊
@@onecircuit-as 3pin fans will always be voltage controlled for speed, 4pin fans can be controlled using voltage or pwm. 3 or 4 Pin PC fan wiring is always the same: GND, 12v, RPM, PWM (Pin: 1,2,3,4). Also if you plan to run the fans on max all the time there is no need for a soft start as that is built into the fans. The max most 12v pc fans can run at is around 16v before you fry them. But running them at anything higher then 12-13v will degrade them as well. All you should need is a buck converter to lower the voltage to 12v and add a pot to lower the voltage if you want to control the speed to run slower. I think the lowest voltage the fans will start at is around 5v.
@@pheelix- I'm definitely more fascinated by soft start circuits than I need to be! 😁
@@pheelix- I highly agree that your suggestion of a SMPS is an efficient way to power the fans. I would only offer that SMPSs are electrically noisy and that it would be good to consider how to manage that noise, within an EE lab setting. My guess is that the best way is to not use one in the lab. With all due respect... Truly.