AnalogDevices < Embedded

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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 <font face="Liberation Serif, serif">&Omega;</font> 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.

<img alt="analogue.png" height="567" src="%ATTACHURL%/analogue.png" title="analogue.png" width="400" />

LED1 simply lights when the board is powered.

These are the analogue boards available in the kit:
   * <p>big and small microphone</p>
   * <p>flame sensor</p>
   * <p>hall sensor</p>
   * <p>thermistor</p>

| <img alt="flame.png" height="334" src="%ATTACHURL%/flame.png" title="flame.png" width="162" /> | <img alt="hall.png" height="327" src="%ATTACHURL%/hall.png" title="hall.png" width="147" /> | <img alt="temperatur.png" height="334" src="%ATTACHURL%/temperatur.png" title="temperatur.png" width="139" /> |
| flame sensor | hall sensor | thermistor |
The same board is used for the
   * touch sensor and a
   * reed switch
which are actually digital sensors.

| <img alt="touch.png" height="356" src="%ATTACHURL%/touch.png" title="touch.png" width="190" /> | <img alt="bigreed.png" height="351" src="%ATTACHURL%/bigreed.png" title="bigreed.png" width="179" /> |
| touch sensor | reed switch |
-- %USERSIG{UliRaich - 2017-01-08}%

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Attachments

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

Topic revision: r2 - 2017-01-10 - uli