The 4-channel temperature sensor board is an adaptation of the 24 channel temperature board used with previous projects including the ESI and DEIMOS instruments. This board is much less complicated in that it does not include multiplexing. The board uses the standard LM35 solid-state temperature sensor in the TO-92 package. The output of the sensor is fed into one section of the LM324 quad op-amp. The gain is set to ten via the R2, 1K ohm input resistor and the R4, 9.09K ohm feedback resistor. The output is then fed to ANALOG INPUT 1 of the Galil motion controller. A second and third LM35 can be added to the system by cabling to the DB9P connectors. Each of these connectors are wired with +5v on pin 6, GND wired to pin 9 and the signal from the sensor wired to pin 3. These signals are then routed to a section of the LM324 and back to the controller via ANALOG INPUT 2 and ANALOG INPUT 3. The last input is wired to the three pin Molex connector which is connected to the output of the 24V power supply. The gain of this channel is set so that the input voltage to ANALOG INPUT 4 measures +5 volts when the input from the power supply is at +24.0 volts. Setting this gain allows the Galil controller programming detect over voltage conditions as well as under voltage conditions. Note: the 300K ohm pull down resistors for circuits 1, 2, and 3 are pulled down to -15V whereas the 1M ohm pull down resistor for the 24V monitor circuit is pulled down to GND. The reason is to allow small negative temperatures to be measured.

 

4 channel Temperature Sensor board