Sensor and control circuit diagrams

Coil Coupled Operation Metal Detector

A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector.

Light Detector Circuit

The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit.

Push-bike Light

Automatic switch-on when it gets dark. 6V or 3V battery operation

Electronic Door Release

The IC is a quad 2 input "AND" gate, a CMOS 4081. These gates only produce a HIGH output, when BOTH the inputs are HIGH. When the key wired to 'E' is pressed, current through R1 and D1 switchs Q5 on.The relay energises; and Q5 is 'latched on' by R8. Thus, the Alarm is set by pressing a single key,say one of the two non-numeric symbols.

Temperature-controlled Fan

Gradually increases speed as temperature increases Widely adjustable temperature range

AC Switch

An AC triggered switch for low frequency signals.

Magnetic-Radiation Remote-Control

Short-range 35KHz operation, single-channel units. Simple circuitry, no outer antennas required

Plant Watering Watcher

A flashing LED signals the necessity to water a plant Very low current consumption - 3V powered circuit

Energy Saving Soldering Station

This circuit appears in the test circuit section because the soldering iron is one of the most used service aids. This circuit, will not only save power when the soldering iron in not in use, but will also preserve the tip life.

Volumetric Sensor Alarm

Detects small variations in air pressure. Can be battery powered (6/12V)