Sensor and control circuit diagrams

Metal Detector

A single chip metal detecor with a range of a few inches. This is useful for decting nails or screws in walls and floors, or for locating buried mains cable.

Hot Water Level Indicator

A simple device to indicate various levels of hot water in a tank.

Water-level Alert

Beeper or flashing LED alert 1.5V battery powered portable unit

Dark-activated LED or Lamp Flasher

Simple photo-sensitive circuit. 3V battery supply

Fridge door Alarm

Beeps if you leave open the door over 20 seconds 3V battery operation, simple circuitry

Schmitt Trigger

This circuit uses a single op-amp and the output is triggered by two different voltage levels.

Laser Communication System

This is a simple Laser communication system. It can transmit and receive signal from any audio device.

Heating System Thermostat

Controlled by indoor and outdoor temperature Simple, high reliability design

Touch Counter

The counter is advanced by one touching a wire of the LED, Suitable for many applications

Infrared Switch

This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz. (This is a very common remote handset frequency). In place of IR1 a TSOP1738 receiver may be used.

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