R
Ray Manning
I'm looking for information on how to build a high temperature sensor for
the HAI Omni Pro II home automation controler.
Here's what I know:
1) The HAI produced temperature sensors send frequency to the board and the
board converts the frequency to temperature
2) The formula for the conversion the board uses is T = F * 15 / 2 for
conversion
3) the omni board does not handle temperatures over 120F, or 16 Hz
What I would like to do is design a sensor which will monitor temperatures
higher than 120F (low pressure boiler water). Since the board can't handle
temperatures over 120F, I see two ways to accomplish this:
1) send a Celsius temperature to the Omni instead of Fahrenheit. This would
give me a high temperature of 120C or about 250F
2) send an offset Fahrenheit temperature, for example (T = T - 100). This
would basically drop the first digit which is quite acceptable in this
situation especially since I use F everywhere else.
Not knowing much about electronics, I'm not sure how to design this thing. I
know I can us a LM34 to get the temperature but that outputs voltage (I only
know that from google searches about temperature sensors for the SECU16). I
don't know how to convert the voltage to frequency which matches the above
formula. I also know the Omni sensors use thermistors based on 10k
resistance and then calculate and convert the resistance to the appropriate
frequency but that's no help to me since I don't know how that's done
either. I know there are voltage to frequency converters but I have no idea
how to hook one up to the LM34 to get the appropriate response.
Any help or pointers on how to proceed?
Thanks,
Ray Manning
the HAI Omni Pro II home automation controler.
Here's what I know:
1) The HAI produced temperature sensors send frequency to the board and the
board converts the frequency to temperature
2) The formula for the conversion the board uses is T = F * 15 / 2 for
conversion
3) the omni board does not handle temperatures over 120F, or 16 Hz
What I would like to do is design a sensor which will monitor temperatures
higher than 120F (low pressure boiler water). Since the board can't handle
temperatures over 120F, I see two ways to accomplish this:
1) send a Celsius temperature to the Omni instead of Fahrenheit. This would
give me a high temperature of 120C or about 250F
2) send an offset Fahrenheit temperature, for example (T = T - 100). This
would basically drop the first digit which is quite acceptable in this
situation especially since I use F everywhere else.
Not knowing much about electronics, I'm not sure how to design this thing. I
know I can us a LM34 to get the temperature but that outputs voltage (I only
know that from google searches about temperature sensors for the SECU16). I
don't know how to convert the voltage to frequency which matches the above
formula. I also know the Omni sensors use thermistors based on 10k
resistance and then calculate and convert the resistance to the appropriate
frequency but that's no help to me since I don't know how that's done
either. I know there are voltage to frequency converters but I have no idea
how to hook one up to the LM34 to get the appropriate response.
Any help or pointers on how to proceed?
Thanks,
Ray Manning
