I have decided to bite the bullet and use the ExpressPCB service so now the boards are on the way to me. Unfortunately I ordered the PCB with the PWM trace error in it. Fortunately it is a very easy board fix, the trace in question run right past the pin it is supposed to connect to.
Now I am assembling a bill of materials and would like some opinions on a suitable PWM frequency for driving fans. As I have it it is running between 250 and >1200Hz depending on gain setting. Is this reasonable?
Some raw specs based on current component values:
Voltmeter 0-23.34V, +/- 2.9mV
Ammeter 0-11.9A, +/- 1.5mA
Giving a Wattmeter 0-278W +/- 0.009mW
Accuracy unknown, component values will be 1%.
4 temperature channels
-40-150°C +/- <0.2°C
0-85°C +/- <0.025°C
18-55°C +/- <0.015°C
2 high resolution temperature channels
15-35°C +/- <0.0025°C
Accuracy unknown, subject to component drifts, tolerances, noise control and accuracy of calibration reference. Who knows? I'll see how the oscilliscope, data noise and repeatability look when it's done.
Last edited by Incoherent; 10-02-2004 at 03:01 PM.
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