too many counts on dual counter and 9490R

[kirk22]

I have a dual counter board hooked up to a 9490R USB adapter. To test I'm using about 8 feet of telephone wire and I only hooked up DQ and GND to the counter board. I measured 5.0V across them.

If I jumper counter A to the +5V terminal I get a few dozen counts. That's probably switch bounce correct?

If I physically hold the wire going to only counter A with my fingers, the counter will increase at the rate of over 3600 counts per minute. That doesn't seem right.

I'm trying to use the counter to monitor Geiger counter clicks as on this web page: http://voksenlia.net/met/radon/radon_e.php

Am I doing something fundamentally wrong?

Kirk

 

[ericvic]

I have a dual counter board hooked up to a 9490R USB adapter. To test I'm using about 8 feet of telephone wire and I only hooked up DQ and GND to the counter board. I measured 5.0V across them.

If I jumper counter A to the +5V terminal I get a few dozen counts. That's probably switch bounce correct?

If I physically hold the wire going to only counter A with my fingers, the counter will increase at the rate of over 3600 counts per minute. That doesn't seem right.

I'm trying to use the counter to monitor Geiger counter clicks as on this web page: http://voksenlia.net/met/radon/radon_e.php

Am I doing something fundamentally wrong?

Kirk

Kirk,

You are not doing anything wrong.

The counter going up at 3600 counts per minute is not surprising. 3600 counts per minute is 60Hz and there is an amazing amount of it floating around in the air. Unless you are well grounded then you act like a big antenna and the counter inputs are pretty high impedance so it doesn't take much to make them count.

Eric