Hi Guys, i'm new here and I know this topic has been beaten to death, but I haven't been able to think up a suitable solution to my design. Here's the breakdown
For my project I am hoping to devise a circuit that turns on a fan at 24 degrees Celsius, and continues to increase the speed of the fan until the fan is at its maximum speed.
However when the temperature drops below 24 degrees I would like the fan to turn itself off.
On top of this, I would like the circuit to controlled by a PWM system.
The chips easy access to are a 555 timer, 358 comparator, 4013 latch, 4017 counter and various logic chips. I have an ADC and DAC already constructed though I'm not sure if they are neccessary. I plan on using a thermistor as the temperature sensor.
One way I have heard you can construct a PWM power control system is by having:
Astable---Counter---DAC-------------
...................................................Comparator-----Transistor---Fan
.............................Anologue Input--
(the dots are just for spacing)
However I am getting a bit confused by this circuit, would somebody be able to explain it to me as I am confused as to why all those chips are necessary.
And if possible a suggestion of a better block diagram would be fantastic.
Thanks
Mike
For my project I am hoping to devise a circuit that turns on a fan at 24 degrees Celsius, and continues to increase the speed of the fan until the fan is at its maximum speed.
However when the temperature drops below 24 degrees I would like the fan to turn itself off.
On top of this, I would like the circuit to controlled by a PWM system.
The chips easy access to are a 555 timer, 358 comparator, 4013 latch, 4017 counter and various logic chips. I have an ADC and DAC already constructed though I'm not sure if they are neccessary. I plan on using a thermistor as the temperature sensor.
One way I have heard you can construct a PWM power control system is by having:
Astable---Counter---DAC-------------
...................................................Comparator-----Transistor---Fan
.............................Anologue Input--
(the dots are just for spacing)
However I am getting a bit confused by this circuit, would somebody be able to explain it to me as I am confused as to why all those chips are necessary.
And if possible a suggestion of a better block diagram would be fantastic.
Thanks
Mike