K8055: Analogue output DC

Kits PC Related Projects
1

Hi

I want to use K8055 to help me use a PC fan as an anemometer/ peak air-flow meter and it’s OK with taking the yellow fan cable and using ReadCounter() on digital input i1: really cool! I can get an accurate RPM in a c# app.

But to get Readcounter() I need some power to the fan. I wanted to throttle back the input voltage so it was just enough to overcome the inertia from the fan coils which I’ve done with a variable DC power supply. 2.1v holds the fan just stationary, so a light wind turns it and also gives power to get the counter reading off the yellow cable.

But then instead of using the external supply I thought I could use DAC1 off the K8055, which gives 5v and is enough to turn the fan. But I guess it’s AC? So it won’t work.

Can I change the output of DAC1 to DC so this just works? Do I use a rectifier?

Or a different approach? If anyone has done something similar?

thanks
Lythy

2

[quote]But then instead of using the external supply I thought I could use DAC1 off the K8055, which gives 5v and is enough to turn the fan.[/quote]The analog output of the K8055 can supply 3mA max. There is 1k5 series resistor in the analog output. The purpose of the resistor is to protect the operational amplifier from overload.

[quote]But I guess it’s AC?[/quote]The analog output is a DC voltage varying from 0 to about 5 volts