I’m looking at an idea for a circuit design; The idea is to sense a temp of 130 degrees and then light an LED and start a timer delay. The delay would be 3 min, after the delay if the temp is still above 130 sound alarm.
With the LED I would like to drive a counter display to show how many times the temp was sensed. I would like powered by 120vac and a 9 volt battery backup for counter circuit.
If you can assist please let me know.
Mail from NV USA 2004
The circuit you require is possible, what is the time frame within which you require it ? You also need to tell the resolution you require is it 130 or 130.0 and counter upto 9999 ? what are the controls you want and the outputs required if any.
I can design above with simple analog-digital based circuits, microcontroller based designs will
take much more time but can be upgraded easily.
Reply from delabs
Pan and Zoom the Circuit for detailed Study here – Pt-100 RTD Four Point Alarm
130 1%, at least 0-999…
a reset for counter and I would like the temp sensor to have 4 sensors so I could surrond a pipe and any sensor would trigger circuit. The unit would be mounted about 6-8 inches away from sensors. Thinks a probe type sensor so it can protrude from a plastic tube that wil be sheped to meet pipe or vent design.
I might not need AC if the circuit can be powered from 9 VDC battery like a Smoke detector.
Mail from NV