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 […]
Newly Updated Circuit Projects:
Audio Delay Line Circuit – For Echo, Reverb Effects
An audio delay line is a technique in which a given audio signal is passed through a series of digital storage stages, until the final audio output is delayed by a certain period (usually in milliseconds). When this delayed audio output is fed back to the original audio, it results in an amazingly enhanced audio, […]
Soft-Start Power Supply for Amplifier Loudspeakers
The proposed slow-start power supply circuit is specially designed for power amplifiers to ensure that the loudspeaker connected with the amplifier do not generate the loud and unwanted “thump” sound during power switch ON. This also implies that the power supply will safeguard or protect the loudspeaker from the sudden inrush current transient from the […]
Touch Volume Control Circuit
This touch volume control circuit has two touch pads which enable the user to increase or decrease the volume of an audio amplifier simply by touching the relevant touch pads. The advantages of this solid-state volume control are: very long life due to the absence of any wear and tear, quick and easy finger touch […]
Loop-Alarm Circuits – Closed-Loop, Parallel-Loop, Series/Parallel-Loop
In this article I have explained a few simple loop based security alarm circuits, categorized under closed loop, parallel loop, and series/parallel loop. All these designs could be customized and used for a variety of security alarm applications. Overview In a loop alarm circuit, more than one sensor is used, each one wired with a […]
Stud Finder Circuit – Find Hidden Metals Inside Walls
A stud finder is an electronic device specially created for scanning concrete walls and locating metallic objects, such as nails, bolts, pipes, hidden beneath the wall. In the following post I have explained a very simple two-transistor metal detector that you can assemble in an afternoon or two and have fun with using for hours […]