I wanted to read a pin and do a digitalwrite to an field effect Transistor to drive a fan.
In front of the board I have 22V ac power which is put in a bridge to convert it to dc then put on a LM317 voltage regulator (100nF in Front and back circut. It outputs me 11,6V. That 11V go in the Arduino raw port.
But for sone reason the Regulator got hot very quickly (seconds) even no fan was attached.
But it shouldnt because the Arduino doesn't dram much power I suppose. (anyone knows the exact ammount?)
So I disconnected my power and attached the circuit to my USB FTDI and it's power.
Now my Voltage regulator doesn't get hot but to my surprise the Arduino still.
The Atmega chip as well as voltage regulator on the Arduino board get hot in seconds you burn your fingers when trying to touch it (as my voltage regulator before as well).
Sounds like either its fried or its getting CMOS latch-up - is there any chance its being back-powered via the fan/FET circuit somehow?
In other words disconnect everything from the Arduino except the USB serial cable and check again
(if it gets hot immediately unplug).
Powering any Arduino from 12V should make the regulator very hot, that's expected, you might want
an external regulator chip on a heatsink, or a DC-DC converter.
I desoldiered it and it got as hot as before also the A0 Pin I used was defective.
A new board seems to work before soldering in.
Can someone have a look about my circiut pls? -- Schematic attached.
Is 2.2k pot ok? Was the only I had. Should be about 2mA through
What about the capacitors at the voltage regulator? Do I need to add an bigger capacity maybe? Would be better if not neccessary since the board is finished and I got no space....
Your "AC" looks like your "DC". The "-" on the bridge rectifier is just barely different from the "+". It really is supposed to be DC going to the fan, isn't it?
Yes it's 100nf on both sides now. Datasheet sais 1yF at output but 100nF was the biggest available.
And fan is connected to DC I made an error in my drawing.
But should I add a bigger capacity after the rectifier or the regulator?
Gorkde:
Yes it's 100nf on both sides now. Datasheet sais 1yF at output but 100nF was the biggest available.
And fan is connected to DC I made an error in my drawing.
But should I add a bigger capacity after the rectifier or the regulator?
And What about my diode or the 2.2k?
100nF is totally inadequate for AC rectification in this case. The minimum value depends on the current draw of the fan, but it will be several hundred uF.
No I checked the wiring already it's fine but I think I touched something while connecting for testing. Still works except getting hot and A1 is dead..... but since I habe another one I use another...
Capacity:
You're right.... I didn't think of the fan being fed by the DC voltage as well....... I did only think of the Arduino..... Damn.... no space left on that board.... So another ugly "Addon" component.....
Edit:
Added 1200uF now with some cable.
Should do the job.
Will check all functions before adding the next pro board.
Already tested that pro board without my circuit and it works.
Even an 2-wire fan is probably a brushless fan. They are just so common these days. There's a tiny little microcontroller in there that tries to keep the fan running at the correct speed, no matter what voltage you give it. An analog voltage is OK. It will spin faster with more volts.
But a PWM waveform trying to control it? The fan just runs at its normal speed for as long as it can.
It is after I powered it up enough Need to change it anyway. But I got my voltage regulator for the next one.
What I wanted to know is if I need to get a PWM Fan because the normal ones can't be controlled by a PWM as it seems. MorganS confirmed it.
So I need to get a PWM fan or control it by Voltage as I did before right?
I switched to PWM because the voltage option got my regulator too hot when turning on low rpm.
Your original circuit had NO filter/smoothing capacitors.
Please read comments on this diagram.
You will have 31Vdc unregulated at the input of the LM317 and supplying the Fan!!!!
Hi,
This is how I think you have your circuit configured, if you did not have the 1200uF in circuit when you first started then your ProMini would have been supplied with pulsed DC, I don't know if it would cause any damage.
Is your MOSFET a logic level device?
What voltage is your Fan?
Need to change it anyway. But I got my voltage regulator for the next one.
