PC voltmeter / datalogger

[scorman]

I am currently constructing a wind turbine and have a wireless
weatherstation which has a puter interface to collect the wind speed
data.

I need to characterize the efficiency of the turbine, so there is a
need to correlate the windspeed with the DC voltage across the 1KW
load. The requirements are simple ...DC measurement, resistor bridge to
get 180v max down to PC level 5v max at the ADC, low freq response ie
1 measurement per second would be fine for averaging purposes

I have researched the inexpensive means to accomplish this by using
either the audio card input or the parallel port.

Does anyone have any comments on the following implementations or a
recommendation for other links of suitable capability:

http://www.techmind.org/ucapwas/ppadc.html
http://home.planet.nl/~m.f.hajer/hardware.html

TIA,
Stew Corman from sunny Endicott

BTW, an alternate project would be a NiMH battery tester under load
using same hardware with a 555IC to apply the load and remove load for
time measurement to threshold of 1.0V per cell

 

[Don Cleveland]

I am currently constructing a wind turbine and have a wireless
weatherstation which has a puter interface to collect the wind speed
data.

I need to characterize the efficiency of the turbine, so there is a
need to correlate the windspeed with the DC voltage across the 1KW
load. The requirements are simple ...DC measurement, resistor bridge to
get 180v max down to PC level 5v max at the ADC, low freq response ie
1 measurement per second would be fine for averaging purposes

I have researched the inexpensive means to accomplish this by using
either the audio card input or the parallel port.

Does anyone have any comments on the following implementations or a
recommendation for other links of suitable capability:

http://www.techmind.org/ucapwas/ppadc.html
http://home.planet.nl/~m.f.hajer/hardware.html

TIA,
Stew Corman from sunny Endicott

BTW, an alternate project would be a NiMH battery tester under load
using same hardware with a 555IC to apply the load and remove load for
time measurement to threshold of 1.0V per cell

Take a look at:

http://www.dataq.com/194.htm

for $25 you couldn't built it for that. They also have a USB unit for $50

Don

 

[Jan Panteltje]

I have a Philips PCF8591 AD / DA chip via i2c on the parport.
It gives me 4 channels analog in and one channel analog out.
Connected via an audio 'diode cable' (2 x single screened).
The ref is a LM317, and the thing runs on an AC / DC adapter, but you
could just as well grab 5 V from the parport, that chip uses micro amps.
It is is an 8 bit ADC, and I added input protection etc...
It costs 6Euro30 or maybe 10 $.
http://www.alscomposants.com/boutique/liste_produits.cfm?type=18&code_lg=lg_fr&num=2
has been working now for eeh 12 years and still going strong.
I2C protocol via parport has the advantage that in a multitasking OS
interruptions in the data or clock due to task switch delays have no effect and
cause no errors.
I also have some PCF8574 IO expanders to do digital IO on the same bus.

 

[scorman]

Don Cleveland wrote

http://www.dataq.com/194.htm

for $25 you couldn't built it for that. They also have a USB unit for $50

Don

Don, thanks for the link ..I hadn't found anything prepackaged for
under $150

Stew

 

[Rich Webb]

Don Cleveland wrote


Don, thanks for the link ..I hadn't found anything prepackaged for
under $150

Be advised that the 194 has a fixed input range and a relatively low
input impendence. It's fine for a lot of things (and may be great for
your application), just know what you're getting.

A lot of supplemental info on the 194 and its relatives is available at
http://www.ultimaserial.com/faq.html

 

[GPG]

Don Cleveland wrote





under $150

Stew

http://www.velleman.be/ot/en/product/search/?id=K8055

 

[jasen]

I am currently constructing a wind turbine and have a wireless
weatherstation which has a puter interface to collect the wind speed
data.

I need to characterize the efficiency of the turbine, so there is a
need to correlate the windspeed with the DC voltage across the 1KW
load. The requirements are simple ...DC measurement, resistor bridge to
get 180v max down to PC level 5v max at the ADC, low freq response ie
1 measurement per second would be fine for averaging purposes

I have researched the inexpensive means to accomplish this by using
either the audio card input or the parallel port.

Does anyone have any comments on the following implementations or a
recommendation for other links of suitable capability:

the analogue pins of the joystick port can be used as a crude ADC over a
limited range.


V ---/\/\/\---+---->|----+5V
|
`----------joystick input

-----------------------0V

response is inverse-linear - ish
so it won't go all the way to 0V, a pull-up could probably be added
parallel to the diode to fix that.

for high voltage make the resistyor large.

every system is different, so you'd have to characterise it yourself.
precision will be no better than the stability of your PC's PSU.


Bye.
Jasen

 

[Mike Monett]

the analogue pins of the joystick port can be used as a crude ADC
over a limited range.

V ---/\/\/\---+---->|----+5V
|
`----------joystick input

response is inverse-linear - ish so it won't go all the way to 0V,
a pull-up could probably be added parallel to the diode to fix
that.

for high voltage make the resistyor large.

every system is different, so you'd have to characterise it
yourself.

precision will be no better than the stability of your PC's PSU.

Jasen

Jasen, is the diode in backwards? What does it do?

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm

 

[Mike Monett]

Jasen, is the diode in backwards? What does it do?

OK, never mind. I found some good sites that explain more how the
game port works, and it doesn't appear to do what I need.

Just for reference, here's some info on this interface:

http://en.wikipedia.org/wiki/Game_port

http://www.faqs.org/docs/Linux-mini/IO-Port-Programming.html#ss6.2

http://www.techedge.com.au/tech/pcthermo.htm

http://webster.cs.ucr.edu/AoA/DOS/ch24/CH24-1.html

Tomi Engdahl has probably the best site:

http://www.epanorama.net/documents/joystick/pc_joystick.html

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm

 

[jasen]

Jasen, is the diode in backwards? What does it do?

over-voltage protection.

the joystick input is basically current sensitive

(on old hardware it was a LM558 or LM556 based monostable
with the joystick being the 0..250K timing resistor to +5V )

Bye.
Jasen

 

[Mike Monett]

over-voltage protection.

the joystick input is basically current sensitive (on old hardware
it was a LM558 or LM556 based monostable with the joystick being
the 0. 250K timing resistor to +5V)

Jasen

Thanks. As I found out, the game port is really slow and not very
accurate. I listed some url's in another post. You can do a lot
better on the parallel port.

I think I have an idea for sending binary data on the soundblaster.
This would allow response to DC and give reasonable data transfer
rates very inexpensively. Just encode the data in MFM. It has no DC
component, and you can use illegal codes for the sync byte.

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm

 

[joseph2k]

I am currently constructing a wind turbine and have a wireless
weatherstation which has a puter interface to collect the wind speed
data.

I need to characterize the efficiency of the turbine, so there is a
need to correlate the windspeed with the DC voltage across the 1KW
load. The requirements are simple ...DC measurement, resistor bridge to
get 180v max down to PC level 5v max at the ADC, low freq response ie
1 measurement per second would be fine for averaging purposes

I have researched the inexpensive means to accomplish this by using
either the audio card input or the parallel port.

Does anyone have any comments on the following implementations or a
recommendation for other links of suitable capability:

http://www.techmind.org/ucapwas/ppadc.html
http://home.planet.nl/~m.f.hajer/hardware.html

TIA,
Stew Corman from sunny Endicott

BTW, an alternate project would be a NiMH battery tester under load
using same hardware with a 555IC to apply the load and remove load for
time measurement to threshold of 1.0V per cell

My first thought was an FPGA experimenters kit on USB for about $49, it even
includes toolkits for doing almost anything with the on board ADC and DAC.