Mobile Phone Multipower Unit
Most of the mobile phone complaints are related to the power supply. This is mainly because of improper charging and use of non-recommended chargers...
DC Motor Control Using Single Switch
This is a circuit that controls a DC motor to run it in clockwise, anti clockwise direction and to stop it using a single switch. It has three LEDs that indicate the status of motor; stopped, forward rotation and reverse rotation respectively.
Frequency Counter
A frequency counter measures the frequency of an input signal. These are commonly used in laboratories, factories and field environments to provide direct frequency...
Multiple Appliances Keypad Control
This multiple appliance keypad control circuit employs DTMF technique to switch on/off up to ten appliances. It can be modified to operate up to...
TV Pattern Generator
This single-IC TV pattern generator is useful for fault finding in TV sets. You can correct the alignment of the timing circuits of the...
Mains Interruption Counter with Indicator
This mains interruption counter circuit counts mains supply interruptions (up to 9) and shows the number on a 7-segment display. It is highly useful...
Resistance Measurement Using Sample and Hold Method
A sample and hold circuit, as the name implies, samples an analogue input signal and holds its value until the input is again sampled....
PC Driven LED Display
Here is a PC driven LED display circuit to generate sequentially running light effects using a simple program written in C. The output of...
False Triggering Eliminator for Timer 555
Normally, false triggering of timer IC 555 takes place during power on, resulting in unwanted output, which starts the timer’s time cycle. The circuit...
Garage Light and Security Control
Useful for vehicle owners, this garage light control & security system automatically turns on indoor/outdoor garage lights and raises an alert when an automobile...
5-Band Graphic Equaliser
This graphic equaliser uses low-cost op-amps. Good quality op-amps powered by a single voltage supply are readily available in the market. The op-amp should...
Lead-Acid Battery Charger With Voltage Analyser
Nowadays maintenance free lead-acid batteries are common in vehicles, inverters, and UPS systems. If the battery is left in a poor state of charge,...
LED Hourglass Timer
This circuit (Fig. 1) simulates the old hourglass timer. A total of 32 LEDs create the effect of sand grains passing from the upper...
Precision 1Hz Clock
This precision clock uses just two ICs and one junction field-effect transistor (JFET) in conjunction with a commonly available crystal and a handful of...
RJ45 Cable Tester
Described here is a simple RJ45 cable tester circuit which can be used for testing the RJ45 network cables. The circuit can check...
Light Operated Internal Door Latch
Using this light operated door latch circuit, you can close or open the door of your room remotely from your bed. You just have...
Emergency Ultraviolet Light
This emergency ultraviolet light circuit serves both as an emergency light (using a 6W fluorescent tube) and an ultraviolet light (using a 6W ultraviolet...
Panel Frequency Meter
Here’s a simple panel frequency meter to measure the frequency of 230V AC mains. When you connect it to the 230V AC line, the...