A electronic combination lock is a device which is designed to activate an electrical solenoid locking system whenever the correct combination of numbers are entered into an attached keypad. To build this type of electronic combination lock, normally an electronic circuit with a keypad is used. In the design I have explained in this article, […]
Security and Alarm
Simple Water Heater Alarm Circuit
In this post I have explained a simple water heater alarm circuit which may be used as a safety device for getting indications regarding the switched position of a water heater or a geyser through intermittent buzzer actuation. The idea was requested by Mr. Mathew. Technical Specifications To be frank i am new to your […]
AC 220V Over Current Monitor and Cut OFF Circuit
The proposed AC mains 220 V load over current cut off circuit continuously monitors the current flowing through a connected load. If this current increases beyond a certain preset level, the circuit trips the relay and disconnects the load from the AC. Basic Working This 220 V over current cut off circuit is indeed subject […]
Power Interruption Alarm Circuit for Instant Power Failure Indications
This power interruption alarm circuit will alert you whenever there’s a power failure or an interruption in the mains. In some special conditions it becomes imperative to know whether the mains that powers some important system or circuit is absent. By: Manisha Patel How the power failure alarm works This proposed circuit is connected to […]
Monitoring 220V AC Load Current using Current Transformer [Circuit Diagram]
In this post I have explained a circuit which can be used for monitoring or controlling AC 220V load current by sensing the load current through a contactless current transformer. Figure 1 below depicts a circuit diagram designed for a non contact load current sensing through a current transformer, which seemed to work well. It is […]
How Laser Microphones or Laser Bugs Work
A laser microphone is a security monitoring gadget in which a laser beam is used for detecting audio vibrations across faraway targets, which are normally walls or glass of homes or offices. These devices could be applied for eavesdropping with virtually no chance of getting identified or cover getting blown. Laser eavesdropping gadgets, it is […]