Electronic Engineering Schematics
Four Channel Temperature Alarm - doc00032
The temperature in a pipe is monitored with four RTD Pt-100
Sensors, The type of probe could be Extruder RTD probes with
Bayonet or Compression Fitting, Get it from Omega. To keep
costs low you can choose small thin film RTD sensors, they will
be fast but on rough usage may break.
See another Solution that is about - Temperature
Meters with Analog Recorder Output
The temperature at four points are measured by Temperature
Module and compared with one common setpoint 0-200 deg F, an
alarm output LED out-a goes ON when the measured
temperature exceeds the common setpoint.
The Source design files for this project are here - Four
Channel Temperature Alarm Docs
The time taken to measure the temperature at the 4 points will
be less than 4 seconds. An optional display of the
measured temperature as shown above can be avoided by using a
DMM to adjust the setpoint.
The Analog Timer Module can be set from 0- 30 minutes. If
out-a remains high even after set time a out-b alarm goes
on to sound a buzzer and flash a LED light.
A digital timer is avoided so as to keep costs low, The alarm is
audio-visual, piezo electric buzzer for sound and a flashing red
big 10mm LED for visual annunciation, a digital output is also
given to turn on an optional SSR to power a hooter or to turn
Whenever out-a goes high and low the Counter Module counts from
0000 to 9999. The counter can be reset at any time by pressing a
button. This will count the number of times temperature in pipe
went above the setpoint.
The unit is powered by a 9V battery to backup the counts in
counter module, The LED displays are turned on by a pushbutton
for momentary use to extend battery life.
Back to Design Service and
20th Mar 2020