Electronic Street Light Switch
Here’s a simple and low-cost street light switch. This switch automatically turns on the light at sunset and turns it off at sunrise. The...
Sound Operated Intruder Alarm
When this sound operated intruder alarm detects any sound, such as that created by opening of a door or inserting a key into the...
Twilight Blinker Lamp
During sunset or sunrise, the ambient light is not adequate to lead you through the open doorway or make your way around obstructions. To...
Multipurpose White LED Light
Standard fluorescent lamps and their smaller versions called compact fluorescent lamps (CFLs) radiate light in all directions (360°) and tend to increase the room...
Soldering Iron Temperature Controller
When soldering, sometimes the need arises to control the temperature of the soldering iron. It is not possible to change the solder iron every...
Harvesting Radio Frequency Energy
Most people do not realise that there is an abundance of energy all around us, at all times. We are being bombarded with energy...
Noise Meter
Normally, sound intensity up to 30 dB is pleasant. Above 80 dB, it becomes annoying. And if it goes beyond 100 dB, it may...
Automatic Heat Detector
This automatic heat detector circuit uses a complementary pair comprising NPN metallic transistor T1 (BC109) and PNP germanium transistor T2 (AC188) to detect heat...
Musical Alarm Timer
A timer is a specialised type of clock for measuring time intervals. Here we present a simple musical alarm timer that can be used...
Low-Cost Hearing Aid
Commercially available hearing aids are quite costly. Here is a low-cost hearing aid circuit that uses just four transistors and a few passive components.
On...
