The ultrasonic hand sanitizer circuit detects the presence of human hand through reflected ultrasonic waves, and triggers a relay solenoid pump momentarily for dispensing the sanitizing liquid on the hands of the user. The project uses the popular HC-SR04 ultrasonic sensor module for the required sensing function. Using HC-SR04 The HC-SR04 ultrasonic sensor module is […]
New Circuit Projects
Touch Alarm Circuit
The touch alarm circuit senses the mains hum signal from an intruder’s body and raises the alarm sound. This happens whenever an intruder touches a potential element set as the sensor, such as the door knob, or any object that needs to be protected. If the circuit is linked with the door knob, the circuit […]
Ultrasonic Fire Alarm Circuit using Air Turbulence Detection
The simple ultrasonic fire alarm circuit I have explained below detects a fire hazard situation by picking up the variations in the surrounding air waves, or the air turbulence. The high sensitivity of the circuit ensures that even the slightest of air turbulence created by a temperature difference or fire is quickly detected and an […]
Series 2S, 5S Li-Ion Cell Charger using BQ7718
This BQ7718 series 2S to 5S series Li-Ion cell charger is designed to monitor the voltage of each of the li-ion cells independently, with reference to an internally set reference level. As soon as any of the cell voltage tends to go above the reference level, it triggers an internal delay timer. This delay timer […]
5 Digit Frequency Counter Circuit
This digital frequency counter will provide a direct reading of the frequency applied at its input, through a 5 digit common cathode display module. The compact frequency counter can be used for accurately counting the frequency or pulse from any intended source. Main Applications It can be also used for measuring the RPM of a […]
Ni-Cd Low Battery Monitor Circuit using Lambda Diode
The main feature of this lambda-diode low battery indicator for Ni-Cd batteries is that, the circuit itself consumes almost zero current, until the set low threshold level is reached and the indicator LED is illuminated. This feature makes the circuit very suitable for many low voltage battery operated systems, like radios, watches, timers, alarms, remote […]
