I don't consider this off topic, since it relates to measuring things
with your PC; could be in the shop or elsewhere. This is just a report
on a neat, cheap device that works for me.

I just bought the $199 HF solar collector outfit just to stick my toe in
the water with photovoltaic solar (PV, they say).

Back in 2003, I saw an ad for a data acquisition unit that plugs into
the back of the PC, into a serial port and using a com port for interface.

This company, Dataq (www.dataq.com), makes a lot of different DAUs
(Data Acquistion Units), at a lot of different prices. The one I bought
costs (still) $25 and includes the hardware to read in 4 analog channels
and 2 digital channels and some Windows based software (on CD)that
allows you to graph and record the signals. Even comes with a
screwdriver to tighten the wires onto the terminals). It is the model
DI-194RS.

I have it hooked up to my new solar collector where it is happily taking
readings on the collector voltage and total current.

There are some limitations on voltage input +-10 volts max, and the
software could do a lot more. But with a well chosen shunt for the
current and a voltage divider for the collector ouput, the graphing
system is perfectly usable. Beside, you can export the data to Excel
anyway.
The only other limitation of note is that the analog channels are
not isolated from eachother, so it may take a little creativity in that
area.
Anyway, I am tickled with the device. It cost only $25! The next
higher featured unit is about $300 and they go up from there, but so what?

Should be adaptable to lots of uses. A great way to get familiar with
data acquisition.

Pete Stanaitis
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