This article is about a software controlled, parallel port-interfacing 8-channel Pulse-Width-Modulated fan controller.
This article was previously published at http://www.hardware-testdk.com/test_show.asp?id=1870 , but I'd like to spread the idea further, possibly sparking new ideas in some of you, so I'm releasing it here too.
I'll admit that the electronic part of it isn't very advanced, but hopefully the idea of "interfacing" might be interesting.
My old partner and I were working on an improved version, using an ULN2803A instead of the many BC547B's and optional zener diodes to make sure the fans always got power from power-on, but he lost interest and so we never finished it.
A "concept sketch" of a not-yet-tested NextGeneration diagram is here:
I did improve the software on my own, though:
- improved fan control routines/speeds
- command line parameters to adjust the power level during runtime
- "KITT(Knight Rider)" running light functionality to the outputs, which looks pretty cool with 8 LED's attached
- and an output be set to turn on at a certain time now - for alarm clocks, a coffee machine or something ?
A Polish guy had asked me for the command-line functionality, and after getting it to work I let him play with the
new program, and he hasn't reported any bugs. I haven't personally thoroughly tested it, though - but it has worked perfectly in my short-time tests.
Source: Electronics Lab