A red LED indicates out of range temperature and in sustained events( where this indicates out of range temp which is counted, displayed and timed) a large LED is lit. In a event where the sustained event exceeds 6 days an alarm is sounded to indicate a possibility of a system failure.
Now I need help on how to come up with the correct circuit diagrams which can work , how to simulate and to get the project done, please help, even direct me to books on the project or other sites please...
Mail from AM South Africa
First acquire the room temperature as an analog value. This requires a sensor for the range you indicated a Semiconductor sensor like LM335 will do fine.
Use the ideas on this page - Circuit Design Service and Projects
Now monitor and generate Logic outputs for temperatures out of range using a Window Comparator. Then for the timed events you need a Timer circuit. And a Logic to set off the Alarm or Annunciator.
All this can also be done by a PIC circuit if you can write some code. I have given some pages to see, study them, that will be sufficient
- Voltage Comparator Information And Circuits
- Long Duration Relay, up to 20 hours
- Fly Electric! - Temperature Monitor 2
- Quozl's Temperature Sensor Project