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Analogue sensors

All analogue boards are based on the same principle and actually use the same PCB. The only difference is the sensor itself, which is placed between the pins marked S and G.

The two 100k resistors (R3 and R5) provide a voltage divider which creates a voltage corresponding to Vcc/2. This Voltage is compared to the voltage of a second voltage divider consisting of the sensor (installed between S= signal, and G=ground) followed by the 150 Ω resistor R4 and the potentiometer. The two voltages are compared by the LM393 voltage comparator between pins 2 and 3. The voltage level of the second divider is taken out on the A0 pin of the PCB connector, while the output of the comparator is connected to D0. D0 therefore shows which of the 2 voltages is higher. This is also indicated by LED2 (green LED) which lights when the output of the second comparator goes low. This is is case when the D0 output goes high.


LED1 simply lights when the board is powered.

These are the analogue boards available in the kit:

  • big and small microphone

  • flame sensor

  • hall sensor

  • thermistor

flame.png hall.png temperatur.png
flame sensor hall sensor thermistor
The same board is used for the
  • touch sensor and a
  • reed switch
which are actually digital sensors.

touch.png bigreed.png
touch sensor reed switch
-- Uli Raich - 2017-01-08


Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng analogue.png r1 manage 18.4 K 2017-01-08 - 16:23 UnknownUser circuit diagram of analogue boards
PNGpng bigreed.png r1 manage 588.4 K 2017-01-08 - 16:23 UnknownUser reed switch
PNGpng flame.png r1 manage 473.4 K 2017-01-08 - 16:09 UnknownUser flame sensor
PNGpng hall.png r1 manage 638.5 K 2017-01-10 - 20:01 UnknownUser hall sensor + comparator
PNGpng temperatur.png r1 manage 2503.2 K 2017-01-08 - 16:08 UnknownUser temperature sensor
PNGpng touch.png r1 manage 1066.5 K 2017-01-08 - 16:07 UnknownUser touch sensor
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Topic revision: r2 - 2017-01-10 - uli
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