Hello again :)
I will be making an Arduino fan controller which will regulate the voltage on the fan with the help of the LM317 Voltage Regulator, now I have made a schematic and I have a question:
The input voltage will be 12V from a PC PSU, will the LM317 be able to give 12V output?
(http://img821.imageshack.us/img821/3627/schematicv10.png)
The input voltage will be 12V from a PC PSU, will the LM317 be able to give 12V output?
No.
You need a voltage greater than 12V say 14V to get 12V out. Also you have no input or output capacitors and have you allowed for the Vssat voltage between collector and emitter when the transistor is on?
You also need resistors in the base of the transistors to limit current flow.
The input voltage will be 12V from a PC PSU, will the LM317 be able to give 12V output?
No, the chip has a regulator drop out voltage specification. It's dependent on how much current is being drawn from the regulator and is about 2 volts at 1 amp drop, so plan on around a 10vdc max output for the regulator if being supplied with +12vdc.
Also be sure to add series current limiting resistors going to the base of those switching transistors.
Lefty
Thanks for the replies guys ^_^
Any idea on how I would get more than 12V with a PC PSU?
I will be making an Arduino fan controller which will regulate the voltage on the fan
I am assuming the fan is 12V, the simple answer is not to use a regulator circuit like this but to use a FET driver in the continuous (non switched) mode.
Any idea on how I would get more than 12V with a PC PSU?
I assume PC supplies still have -12V outputs.
-12 to +12 is 24 volts.
Any idea on how I would get more than 12V with a PC PSU?
I assume PC supplies still have -12V outputs.
-12 to +12 is 24 volts.
Not really usable that way in a common grounded system.
Lefty
Depends what you declare "ground" to be.
Depends what you declare "ground" to be.
Correct, we would need to know if he is using the PC supply for any other loads, or desires to.
Lefty
I'll be using the same PSU for: Pumps (Water Cooling), Micro Controllers, Fans
Mike has the best solution; use a single power FET and control it with a PWM output from Arduino. And it (could) handle a lot more current than an LM317T.
Nothing against the LM317T. I once bought a barrel of 14,000 of them for $55 from a junkyard near IBM :) I'll send 5 to anyone who'll send a SASE... I still have about 500 left.
---------------------------------------------------------------------
UPDATE: Sorry! I'm always criticizing Acronyms...
Self-Addressed-Stamped-Envelope (sent to me, will return 5 LM317t's..)
Terry King
152 Colby Road
West Topsham, VT 05086
But: 3 weeks till I get there from the Middle East...
Can you give me more info on using FET's with Arduino? Schematic(s), Maybe even some example code ;)
Maybe even some example code
analogWrite(pin, value);
Schematic(s)
use the PWM output filtered and into the gate
http://www.thebox.myzen.co.uk/Tutorial/PWM.html (http://www.thebox.myzen.co.uk/Tutorial/PWM.html)
So I use Frequency dependent potential divider with low pass filter connected to a FET, and the divider is hooked up to Arduino PWM output pin? And if so, which FET should I use?
Frequency dependent potential divider with low pass filter
close:-
Frequency dependent potential divider AS low pass filter.
which FET should I use?
Any one that will take at least 200mA (most will) and is a logic level FET.
The FET will get hot because you are burning the excess voltage off inside it when it is not full on. The power dissipated will be with half the voltage dropped across it at what ever current the motor runs with only half the voltage across it. You might need a heat sink.
@Grumpy_Mike
Thanks! :D
I hope I'm not too annoying with all these questions :P, maybe something like this? http://www.nteinc.com/specs/2900to2999/pdf/nte2987.pdf
Could you also tell me what exactly am I look for? N-Channel MOSFETS?
maybe something like this?
Yes very meaty, that would do.
Alright! :)
Now, if only I could find that in Eagle :P
@Grumpy_Mike
Thanks! :D
I hope I'm not too annoying with all these questions :P, maybe something like this? http://www.nteinc.com/specs/2900to2999/pdf/nte2987.pdf
Could you also tell me what exactly am I look for? N-Channel MOSFETS?
Mouser shows that at $7 a pop: http://www.mouser.com/ProductDetail/NTE/NTE2987/?qs=sGAEpiMZZMutXGli8Ay4kFfMPLZ9xW8yKOlRS6m%252bwN0%3D
Sparkfun sells a logic level N-channel power mosfet for a buck: http://www.sparkfun.com/products/10213
Lefty
I said it was meaty. :)
I found something a bit cheaper than the previous I linked and am not sure if it will work...
http://eu.mouser.com/ProductDetail/Fairchild-Semiconductor/FDP6030BL/?qs=sGAEpiMZZMutXGli8Ay4kBEMMAKgSkd8MdwkNnQ%2fGU8%3d
Hi,
Speaking Of FETS... I would like to decide best 2 or 4 power NFET and PFET to stock for use with Arduino...
I would appreciate your suggestions...
Two that have been suggested are:
RFP30N06LE "N-Channel Logic Level Gate Power FET"
FQP27P06 "P-Channel Power FET"
Also maybe a good TO92 or similar small Logic-Gate NFET for cheap routine replacement of small NPNs like 2N2222 ??
What has been working well for you???
I'll make these available at a decent price in my online store...
Thanks!
Can anyone tell me what I must pay attention to when choosing a FET for using it to regulate voltage with Arduino?
Turn on voltage, it should be rated at 5V and have a low Ron at this value. At most 0.01R.
It should be in a package that allows good power dissipation because as I said it will burn off the excess power.
@Grumpy_Mike
So: N-Channel FET, TO-220, 5V Turn on voltage, low on resistance, low resistance drain-to-source, and of course, drain source voltage high enough and same for current ?
Yes.
drain source voltage high enough and same for current
You will struggle to find one that is not high enough.
I think I found something that will fit my needs: http://eu.mouser.com/ProductDetail/Fairchild-Semiconductor/FDP7030BL/?qs=sGAEpiMZZMvECErq9cesgOhjwE8m5zTM4sOaJqrLpIU%3d
Now for the (hopefully) last question: How do I connect everything? :P
Something like this?
12V
|
|Source pin
|
|Digital Pin 9|----|Resistor|----|Capacitor|--Gate--|MOSFET|
|
|Drain pin
|
Load(Fan)
|
|
|
GND
Nothing against the LM317T. I once bought a barrel of 14,000 of them for $55 from a junkyard near IBM :) I'll send 5 to anyone who'll send a SASE... I still have about 500 left.
Cool! Would 2 "forever" stamps be sufficient postage? Maybe 3 to be sure, eh?
Thanks, Terry.
No like this
12V
|
Load(Fan)
|Drain pin
|
|Digital Pin 9|----|Resistor|-------------Gate--|MOSFET|
| |
|Capacitor| |Source pin
| |
| |
| |
| |
| |
GND GND
The way you had it:-
1) the capacitor would block the DC signal and nothing would get too the gate
2) you would not get any more than 5V across your fan
Thank you! :D
Cool! Would 2 "forever" stamps be sufficient postage? Maybe 3 to be sure, eh?
Under Terry's name it says "Red Sea/Saudi Arabia" so my
guess would be "no."
For the divider I'm not sure if 1k resistor and a 18uF capacitor will suit my needs...
For the fan control I will be regulating 12V, the voltages which will be "available" for the fans are: 7V, 8V, 9V, 10V, 11V, 12V and will be changed as the temperature of the CPU Changes. I'm expecting the voltage change to occur no higher than 2x a second.
For the divider I'm not sure if 1k resistor and a 18uF capacitor will suit my needs...
I am not sure where you got these values from. An 18uF capacitor is very non standard, 10uF , 16uF and 22uF are the closest values.
However, it is not very critical as it is only a second order filter and the slope here is not steep.
You will have to experiment as to what PWM values you have to get to give those voltages to the fan. This is because you are relying on the non saturated part of the curve and it is not consistent from device to device.
I'm currently "worried" so to say about the divider.
Will it allow me to change the voltage 2x a second?
1K and 18uF is a time constant of :-
1 103 X 18 10-6 = 0.018 seconds
So yes it will not hamper a signal at 0.5 seconds period.
Ok, so I finnaly got my hands on all the parts I need, but there's a problem... It's not working :(
When I tap the FET the fan starts spinning and if I don't do that nothing happens...
I'm guessing that the FET is damaged, but am not sure...
What do you think?
Under Terry's name it says "Red Sea/Saudi Arabia" so my guess would be "no."
I believe that Terry also has a residence in Vermont.
Don
Under Terry's name it says "Red Sea/Saudi Arabia" so my guess would be "no."
I believe that Terry also has a residence in Vermont.
And, in fact, he's there now. Having some trouble with the forum though.
http://arduino.cc/forum/index.php/topic,65627.msg480338.html#msg480338
No like this
12V
|
Load(Fan)
|Drain pin
|
|Digital Pin 9|----|Resistor|-------------Gate--|MOSFET|
| |
|Capacitor| |Source pin
| |
| |
| |
| |
| |
GND GND
The way you had it:-
1) the capacitor would block the DC signal and nothing would get too the gate
2) you would not get any more than 5V across your fan
hello can you provide code? thls