Hello,
I'm starting a project where I use a 12v dc adaptor 300mA.
I also have a 12Vdc 1.5A adaptor.
Which one should I use best and what transistor schould I use?
The fans are bot 12dc Voltage. And I want to regulate the power with arduino to run at half a speed of a gentle suction and gentle ventilation.
Kind regards!
All depends on the type of 12 volt fans you have. If they have their own internal switching circuitry, they won't run on less than about 10 volts DC.
Paul
Paul_KD7HB:
All depends on the type of 12 volt fans you have. If they have their own internal switching circuitry, they won't run on less than about 10 volts DC.Paul
Hi,
to be precise they are 12v dc 0.1A fans and they only have 2 wires no tacho wire.
Brushless DC fan no other info on it.
@Paul How can I found out if it has a onboard circuitry?
beyondal:
@Paul How can I found out if it has a onboard circuitry?
You just said they're brushless... that already answers that question.
Chances are they react just fine to PWM.
wvmarle:
You just said they're brushless... that already answers that question.Chances are they react just fine to PWM.
Are there examples with two wire fan? Or better what search term should I put in to google 
Because all I get are the 3 wire examples.
Thanks for the reaction!
Your 2-wire fan is basically just a BLDC motor that happens to have some aerofoils attached to it.
wvmarle:
Your 2-wire fan is basically just a BLDC motor that happens to have some aerofoils attached to it.
And what does that say about the usage of the adaptor and de mAh or how to wire it?
Should I post a picture of the fan?
I thought to use this setup and try to figure out which transistor I need for this.
mA rating is usually printed on the fan - in your case that seems to be 100 mA for each.
Two wires, one for V+ and one for V-. Don't swap them, you'll probably destroy the internal control electronics.
At 100 mA just about any transistor would work. I always prefer to use a MOSFET, IRL540 or IRLZ44N are two examples that come to mind, but a normal BJT will do just fine at this low current. No type numbers in mind, I only use those for small signal switching and 100 mA is out of that realm.
I definitely wouldn't go for a darlington such as the TIP120 in your schematic for the large voltage drop (about 2V typically). I don't see much of a point of using darlington transistors in modern electronics, really. It'll do the job just fine, though. A little less power for the fan, that's the main issue.
wvmarle:
mA rating is usually printed on the fan - in your case that seems to be 100 mA for each.Two wires, one for V+ and one for V-. Don't swap them, you'll probably destroy the internal control electronics.
At 100 mA just about any transistor would work. I always prefer to use a MOSFET, IRL540 or IRLZ44N are two examples that come to mind, but a normal BJT will do just fine at this low current. No type numbers in mind, I only use those for small signal switching and 100 mA is out of that realm.
I definitely wouldn't go for a darlington such as the TIP120 in your schematic for the large voltage drop (about 2V typically). I don't see much of a point of using darlington transistors in modern electronics, really. It'll do the job just fine, though. A little less power for the fan, that's the main issue.
So this wiring setup with the actual same data would work correct??
Probably - but considering your image is a Fritzing spaghetti diagram it's 1) hard to figure out how all is connected, 2) missing bits and pieces (the Arduino power supply, for example), and 3) never sure what else has been replaced "because I couldn't find the exact image" (like the motor instead of the fan).
wvmarle:
Probably - but considering your image is a Fritzing spaghetti diagram it's 1) hard to figure out how all is connected, 2) missing bits and pieces (the Arduino power supply, for example), and 3) never sure what else has been replaced "because I couldn't find the exact image" (like the motor instead of the fan).
I know I'm not a fritzing pro
The arduino is powered with a 5v adaptor.
beyondal:
I know I'm not a fritzing pro
The problem lies with Fritzing. Get a real schematic drawing program instead such as KiCAD or EagleCAD, or just use pen and paper. Works great, too. Just about anything is better than the best Fritzing can do.
Wired everything up and it doesn't seem to run my fans...
Is there any good schematic to just try one fan to work?
I get heaps with google. But not sure which one works correctly.
Kind regards!!
