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Latching Water Sensor – Circuit Schematic
Latching Water Sensor
A balanced Wheatstone bridge controls a JK flip-flop that uses an op amp as an interface. This in turn drives a relay...
Moisture Detector – Circuit Schematic
Moisture Detector
A bar-graph LED driver is used to drive 10 LEDs to give a relative indication of moisture. The moisture probes are connec...
Full Bathtub Indicator – Circuit Schematic
Full Bathtub Indicator
Running a bath can end in a minor domestic disaster if you forget to turn off the taps in time. This indicator activ...
Liquid-Level Sensor – Circuit Schematic
Liquid-Level Sensor
This circuit uses an ac-sensing signal to eliminate electrolytic corrosion. The ac signal is rectified and used to driv...
3V Water-Level Detector – Circuit Schematic
3V Water-Level Detector
Originally, this circuit was used to sense a low-water level in a Christmas tree stand, but the circuit can be use...
Water-Level Control – Circuit Schematic
Water-Level Control
This circuit will power up a water pump when the water reaches a predetermined level. Then it turns itself off when the...
Digital Compass – Circuit Schematic
Digital Compass
A four output Hall sensor combined with a few logic gates produce this digital compass. The NOR gates resolve the four Hall...
Air-Pressure Change Detector – Circuit Schematic
Air-Pressure Change Detector
A piezoelectric detector (BZ1) is used in this circuit to detect a change in air pressure. BZ1 produces a volt...
Detector And Controller – Circuit Schematic
Detector And Controller
Many applications require analog signals to be sensed and digital signals to be controlled. A way to detect these p...
Two-Sheets Detector – Circuit Schematic
Two-Sheets Detector
Using the principle of capacitance between two plates this circuit senses when more than one sheet of paper goes betwee...
Thermally Operated Direction Detector – Circuit Schematic
Thermally Operated Direction Detector
A heat-sensitive sensor can be used to construct a direction detector. Such a sensor reacts to all an...
Stalled-Output Detector – Circuit Schematic
Stalled-Output Detector
This circuit can be used to detect a stuck output or node in a circuit, or a loss of data or pulses. The pulse trai...
Data Line Remote Short Sensor – Circuit Schematic
Data Line Remote Short Sensor
Sensing short circuits in equipment that performs under water is especially critical, but Fig. 20-4"s wet-mat...
Air-Flow Sensing Thermistor Bridge – Circuit Schematic
Air-Flow Sensing Thermistor Bridge
Using the thermistor-bridge circuit, you can detect system-cooling air losses caused by filter or inlet ...
Digital Miscellaneous Temperature Gauge – Circuit Schematic
Digital Miscellaneous Temperature Gauge
A diode (IN4148) is used as a temperature sensor. IC2 is an A/D converter with BCD output. A refere...
Digital Vacuum Gauge – Circuit Schematic
Digital Vacuum Gauge
A bridge circuit is used to produce a signal from the output of vacuum sensor IC1. IC2b provides about a 0.2 V offset ...
Digital Oil-Pressure Gauge – Circuit Schematic
Digital Oil-Pressure Gauge
This gauge uses a sensor in conjunction with R1 to develop a dc voltage proportional to oil pressure. IC1 and IC...
Window-detector – Circuit Schematic
Window-detector
The detector circuit compares the output voltage of two separate voltage dividers with a fixed reference voltage. ...
Simplified-voltage-level-sensor – Circuit Schematic
Simplified-voltage-level-sensor
This circuit uses only one JC, either 1, LM393 dual comparator or 1/z, LM339 quad comparator. RV1 and RV3 set the full scale reference voltage, and RV2 and RV4...
Single-supply-wide-range-sync-separator – Circuit Schematic
Single-supply-wide-range-sync-separator
This circuit extracts the sync pulses from a video signal over a wide range of amplitudes and operates a single +15 V supply. IC1 buffers and amplifies the inc...