thanks for the fast responses!
>What resolution is the A2D convertor.?
12 bit. Amounts to 3 bit per centigrade. 10mV per Centigrade, 3.3V reference, 1023 bit.
>Do you have any filtering on the output of the A2D.?
at the output? Logomatic is done by
www.sparkfun.com, so no idea about their filtering. Just wired in the sensors and a few Ls and CS and an LM1117 incl LC filter for the 3.3 V. Normally Logomatic generates 3.3 V on board, did not work all too well. So Excel would do the filtering....
>voltage divider
for testing I just put it on veroboard, was fine.
**broken link removed**
you mean I should gat say 5m cable and just put a voltage divider on and see what happens?
Actually its at home, would there be much noise? Could imagine in an industrial setting.
Anyhow, the sensors get 9V from a 500mA plug wart, then there is an addiditonal LC filter (100mH, and a few Cs in parallel. Then I step it down via TL7805 and LM1117 for the 3.3V and another 100mH and a few Cs before it goes into the Logomatic. The less noisy graphs are on about 3m cable, the others say 8m.
>digital sensor
seems you cannot make the Logomatic log say 1 measurment a minute, can just set a baudrate. Too much date to shift through, its for temperature logging in a house. Even every 5 minutes would be good enough
should I create a few preamps next to the sensors, bump it up by factor 3? Or is there an easier way?