L
larrymoencurly
We Live for the One we Die for the One ([email protected])
www.cpemma.co.uk has plans for both linear and switching fan speed
controllers, but the linear ones are a lot simpler and don't cause
pulsation noise or electrical interference (one person said that his
Vantec controller prevented his floppy drive from working).
I used a couple of one below (legible with nonproportional font, like
Courier), but you can make an even simpler one from an LM317
adjustable 3-pin regulator chip (max. voltage will be only about 10V;
you can raise this to about 11.4V with a low-dropout equivalent chip).
This circuit is almost like from an Enlight (Sirtec?) PSU, and one
nice thing about it sets a lower limit for the fan voltage (change
ratio of R1 to R2 to change this limit); it will also make sure that
the fan runs even if the thermistor wire breaks. Capacitor C2 across
the thermistor was added to apply full voltage to the fan at start-up
because some fans will run at 4-5V but won't reliably start with less
than about 6V. If you want manual adjustment, add a variable resistor
across the thermistor, something rated 5-10 times the room temperature
resistance of the thermistor. This controller and other linear ones
are so small and cheap that you can build one for each fan, and that
way you don't have to worry about blowing up transistors (but bipolar
transistors like these usually short when they blow, so the fan should
simply run at full speed).
^ +12V
|
|
|
-----------------------------|
| | | |
+ | | | |
| | | |
C1 ----- | \ |
10uF ----- | R1 / |
16V | | 390 \ |
| | / |
| | \ |
----- | | /
--- | | |/ Q1
- \ |-----| 2SC1384
/ R3 | | 1A, 1W
\ 91K | |
/ \ |\
\ R2 / >
| 560 \ |
| / |
| \ |
| | |
| Q2 | |
| 2N3904 / o fan+
| |/
| |
|-----------| o fan-
| | |
------| |\ |
| | > |
+ | | | |
C2 | \ | |
50uF ----- / thermistor | |
16V ----- \ (10K @ 25C) | |
| / | |
| \ | |
| | | |
| | | |
----------------------------|
|
|
|
ect.wrote in message said:Ive just heard nasty stories about fan controlers stoping working
www.cpemma.co.uk has plans for both linear and switching fan speed
controllers, but the linear ones are a lot simpler and don't cause
pulsation noise or electrical interference (one person said that his
Vantec controller prevented his floppy drive from working).
I used a couple of one below (legible with nonproportional font, like
Courier), but you can make an even simpler one from an LM317
adjustable 3-pin regulator chip (max. voltage will be only about 10V;
you can raise this to about 11.4V with a low-dropout equivalent chip).
This circuit is almost like from an Enlight (Sirtec?) PSU, and one
nice thing about it sets a lower limit for the fan voltage (change
ratio of R1 to R2 to change this limit); it will also make sure that
the fan runs even if the thermistor wire breaks. Capacitor C2 across
the thermistor was added to apply full voltage to the fan at start-up
because some fans will run at 4-5V but won't reliably start with less
than about 6V. If you want manual adjustment, add a variable resistor
across the thermistor, something rated 5-10 times the room temperature
resistance of the thermistor. This controller and other linear ones
are so small and cheap that you can build one for each fan, and that
way you don't have to worry about blowing up transistors (but bipolar
transistors like these usually short when they blow, so the fan should
simply run at full speed).
^ +12V
|
|
|
-----------------------------|
| | | |
+ | | | |
| | | |
C1 ----- | \ |
10uF ----- | R1 / |
16V | | 390 \ |
| | / |
| | \ |
----- | | /
--- | | |/ Q1
- \ |-----| 2SC1384
/ R3 | | 1A, 1W
\ 91K | |
/ \ |\
\ R2 / >
| 560 \ |
| / |
| \ |
| | |
| Q2 | |
| 2N3904 / o fan+
| |/
| |
|-----------| o fan-
| | |
------| |\ |
| | > |
+ | | | |
C2 | \ | |
50uF ----- / thermistor | |
16V ----- \ (10K @ 25C) | |
| / | |
| \ | |
| | | |
| | | |
----------------------------|
|
|
|