CCFL Tester Circuit For LCD Screens

Lcd's cover a wide range of applications including led tv's to cmputer monitors, PDAs, digital monitors and much more. LCD backlight mainly consists of a light source, diaphragm, light leading board and a plastic frame.  Cold-cathode fluorescent lamps (CCFLs) have a phosphor coated glass cylinder with cathodes at each end. The CCFL inverter accepts a low-level DC input voltage and provides a high-level AC output to run the backlight CCFL tube. Here's a CCFL tester circuit that often needed to check a faulty LCD backlight circuit for finding the dead components.

Guitar Preamplifier Circuit Using IC TL071

Here is the circuit of a electric guitar preamplifier based on IC TL071.The pickup device has a transducer on one end and a jack on the other end. The jack can be plugged into a preamplifier circuit and then to a power amplifier system.

The mechanical vibrations from low frequency bass to a certain extent of high frequency is picked up by a guitar or violin pickup device and converts them into an electrical signal, which can then be amplified by an audio amplifier. This circuit diagram of guitar pre amplifier has two output options - one to a power amplifier and other one could fed to a headphone.

150mW Crystal AM Transmitter

Here is the circuit of a medium power crystal based amplitude modulation (AM) transmitter that can deliver 100-150mW of radio frequency (RF) power.

1Hz Clock Generator Circuit Using COB

Let's familiarize with a COB - chip on board device by building a precision 1Hz clock generator. Circuits that usually generate 1Hz clock makes use of ICs with variable capacitors but they are not very precise. ( micro controller based one should be precise but it costs large ). better accuracy can be obtained by a COB found inside a digital clock, which is cheaply available in the market.

Automatic Muting Circuit For Audio Systems

Here's a circuit diagram of automatic muting for audio systems using IC LB1403. The signal from pre-amplifier such as LA3160, LA3161 or HA1032 is connected to the base of the amplifier transistor BC548 (T1). Variable resistor VR1 is used to control the gain of input signal.

Digital Fan Regulator Circuit

The circuit presented here is that of a digital fan regulator, variable  to provide five speed levels as catered for in ordinary fan regulators. The circuit of ceiling fan controller makes use of easily available components. An optional 7-segment display with its associated electronic circuitry has been provided to display your choice of fan speed.

Water Tank Level Meter

The water-tank level meter described here is very simple circuit diagram and useful for monitoring the water level in an overhead tank (OHT). The water level at 30cm intervals is monitored and continuously indicated by LEDs arranged in a meter-format. When all the LEDs are ‘off’, it indicates that the OHT is empty. When the water level reaches the top limit, the whole LED-meter begins to flash. The height at which the level-sensing electrodes are fitted is adjustable. Thus, the minimum and maximum level settings may be varied as desired. The range of the meter can also be enlarged to cater to any level. No special or critical components are used. CMOS ICs are used tolimit the idle current to a minimum level.

Powerful Pest Repeller Circuit

Most of the electronic pest repeller circuits have a major drawback of low power output hence their effectiveness suffers. The ultrasonic pest repeller circuit described here generates powerful ultrasonic signals therefore efficient to repel pests like mosquitoes. In addition to the ultrasonic frequency oscillator, we use a  separate push-pull power amplifier and transformer  to boost ultrasonic signals.

Bass And Treble Circuit Using Transistor

 This circuit diagram for bass and treble control is effective and using low cost components.

Modern audio frequency amplifiers provide flat frequency response over the whole audio range from 16 Hz to 20 kHz. To get faithful reproduction of sound we need depth of sound, which is provided by bass (low notes). Hence low-frequency notes should be amplified more than the high-frequency notes (treble). To cater to the individual taste, and also to offset the effect of noise present with the signal, provision of bass and treble controls is made. The combined control is referred to as tone control.

Digital Water Level Indicator

This digital water level meter circuit indicates up to 65 discrete water levels in the overhead tank (OHT). This
helps to know the quantity of water in the OHT quite precisely. The circuit is specially suited for use in  apartments, hostels, hotels, etc, where many taps are connected to one OHT. In such cases, if someone for gets to close the tap, this circuit would alert the operator well in time.

Automatic Bathroom Light

This is a circuit of automatic bathroom light which can be used to automate the working of a bathroom light. It is designed for a bathroom fitted with an automatic door-closer, where the manual verification of light status is difficult. The circuit also indicates whether the bathroom is occupied or not. The circuit uses only two  ICs and can be operated from a 5V supply. As it does not use any mechanical contacts it gives a reliable performance.

PC Based Wireless Stepper Motor control Circuit

Stepper motors find lots of applications in process control, machine tools and robotics. Especially in robotics and process control, bit is necessary to control the stepper motor from a remote place. Here you will get the transmitter and receiver circuit diagrams and Full source code for the application program.

Here we describe how to wirelessly control a stepper motor from a remote place by using RF modules. For this wireless stepper-motor control system, you need to design and develop the required hardware and software. The parallel port of the PC is used to control the direction of the stepper motor at the transmitter side. RF interface is used instead of IR to overcome all the drawbacks of the IR interface. The PC signals are transmitted from the RF transmitter and received by the RF receiver.

Seismic Sensor Circuit

This circuit is a very sensitive seismic sensor that detects vibrations/sounds. It can detect seismic vibration or sounds caused by animals or humans. So it can be used to monitor protected areas to restrict entry of unwanted persons or animals.

Laser Switch With Timer

This circuit is a laser controlled relay switch with timer that can be made using readily available components. This laser switch has the following advantages :

• Timed operation - Turn on time of the switch can be controlled
• Large current handling capability, can control a motor
• Stand by and operating mode led indication
• operating mode Piezo alert.

Car Reverse Horn With Flasher

This is a circuit of car reversing horn with normal auto lamp flasher that uses timer ICs NE556 and NE555. When the car is in reverse gear, the switch S1 which is the reverse gear switch of the car get shorted and the monostable timer give a high output. So the diode D1 and D2 goes for high for a time period R4C4. 

Portable Electric Lamp cum LED Flasher

Here's the circuit of a portable type flasher uses 25W, 230V AC bulb and nine LEDs. The bulb and led's glows alternatively. The circuit includes a 555 timer based astable multivibrator which generates a square wave. This output drives the transistor bc547 to riger the gate of lamp controller triac.

Simple Duophone System

Here a simple circuit diagram of duophone that allows you to access two telephone line through a single telephone set. The conversation through each line will entirely private when the conference switch in the dual phone is off. So this duophone circuit has a unique feature of talking to two people simultaneously what is called three-party telephone conversation/conference facility.

Pyroelectric Fire Alarm

Ordinary fire alarm circuits uses diode sensors to detect fire presence. But a pyroelectric fire alarm circuit described here is an ultra-sensitive fire sensor that uses direct piezoelectric property of an ordinary piezo element to detect fire.

FM Booster Circuit to Receive Far Away FM Stations

This is a low cost FM booster circuit to receive far away fm stations clearly on your radio in your local area. The circuit diagram of FM booster consist of a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570.

Solar Charger Circuit For Lead acid, Ni-Cd And Li-ion Battery

The solar panel based charger described here is capable of charging Lead acid, Ni-Cd And Lithium-ion batteries. This circuit diagram is designed for a solar panel which is capable of delivering 5W power. The solar panel outputs 16.5V. It can deliver a current of 300-350 mA.lead acid, Ni-Cd and Li-ion. The lead-acid batteries are commonly used in emergency lamps and UPS.