Light Alarm with Timer 555

Here is the simple and low cost light alarm circuit built using timer IC 555 as the sound generator and a LDR to sense the environment light. This alarm is activated when the light beam on the LDR photocell is interrupted (You can use the light of a flashlight bulb which will make you a… Read More »

Scoring Display with 7 Segment LED

This is the circuit diagram of game scoring display using 7 segment LED. This circuit consist of a timer IC, two decade counters and a display driver along with a 7-segment LED display to show the score. The game is simple. As stated above, it is a scoring game and the competitor who scores 100… Read More »

Aquarium Temperature Probe

This is the electronic circuit diagram of aquarium temperature probe capable to monitor the temperature of water and indicate the rise in temperature through audio-visual indicators. This circuit uses diode 1N34 as the temperature sensing probe. The resistance of the diode will be vary depends on the temperature in its vicinity.

Laptop / Notebook Protector

This is laptop / notebook protector circuit to protect your laptop or notebook or netbook from being stolen. Fixed in-side the laptop case, it will sound a loud alarm when someone tries to take the laptop. This highly sensitive circuit uses a homemade tilt switch to activate the alarm through tilting of the laptop case.… Read More »

Adjustable Symmetric 1 to 24VDC, 1A Power Supply

This is the circuit diagram of adjustable symmetric 1 to 24VDC, 1A Power Supply. This power supply give dual output positive and negatif output, you can adjust both positif and negative output (+1 to +24VDC and -1 to -24VDC). This kind of power supply also known as dual polarity power supply or splitted power supply… Read More »

4 Stage FM Transmitter

This is the FM transmitter circuit which apply 4 radio frequency stages, that are a VHF oscillator designed around transistor BF494 (T1), a preamplifier designed around transistor BF200 (T2), a driver designed around transistor 2N2219 (T3) and also a power amplifier designed around transistor 2N3866 (T4). A condenser microphone is wired at the input of… Read More »

Car Anti-Theft Protection with Buzzer

This is the circuit diagram of car anti-theft to protect and increase the security of your car, prevent your from stealing. This circuit is very simple, low cost and easy to built. When key-operated switch S2 of the car is turned on, 12V DC supply from the car battery is extended to the entire circuit… Read More »

Battery Charger + Small LED Lamp based Solar Cell / Photovoltaic

This is the circuit diagram of rechargable battery charger which use solar cell / photovoltaic as the DC source. This circuit works to charge 3 types of rechargable batteries that are lead acid, Ni-Cd and Li-ion. The lead-acid batteries are generally utilized in emergency lamps and UPS. The photovoltaic module or solar cell explained in… Read More »


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