Bug Detector

This circuit utilizes a complementary pair consisting of an NPN metallic transistor T1 (BC109) and a PNP germanium transistor T2 (AC188) to detect heat in the environment, such as that produced by a fire, and activate a siren. The...

Is a 100 to 200 metre (100 to 200yds) device having a very stable performance. It can be used as a hand held microphone or left on a shelf to pick up the sounds in a room. It has...

This is a basic dark detector or sensor circuit diagram based on a photoresistor (LDR) and a few components. The dark detector circuit utilizes a photoresistor (LDR) as the primary sensing element. The LDR is a light-dependent resistor that changes...

When the 555 IC goes into timing mode (triggered by an output signal from the sound detector amplifier), the timer's output (pin 3) is set to HIGH for a duration set by C2 and R2. Adjusting R1 will adjust...

The metal detector circuit presented here exemplifies simplicity while demonstrating effective functionality. It utilizes a single 40106 hex Schmitt inverter IC, a capacitor, a search coil, and batteries. A connection from IC1b pin 4 must be made to a...

A simple metal detector circuit diagram and schematic using a single transistor and a radio. This metal detector/sensor project is easy to make and is an application of a Colpitts oscillator. The metal detector circuit utilizes a single transistor in...