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Topic: LM317 Help (Read 6604 times) previous topic - next topic

tastewar


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."

Rogy

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.
Ordinary people pursue order, Ingenuous people rule chaos.

Grumpy_Mike

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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.

Rogy

I'm currently "worried" so to say about the divider.

Will it allow me to change the voltage 2x a second?
Ordinary people pursue order, Ingenuous people rule chaos.

Grumpy_Mike

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.

Rogy

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?
Ordinary people pursue order, Ingenuous people rule chaos.

floresta

Quote
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

justjed


Quote
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
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

paulorcrs


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

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