5 band graphic equalizer using a single IC/chip

The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low distortion, low noise, and wide dynamic range, and is an ideal choice for Hi-Fi stereo applica-tions. It also has a wide operating voltage range (3.5V to 16V), which means that it can be adapted for use with most types of stereo equipment.

Click Here For More Details

TV remote control Blocker

Just point this small device at the TV and the remote gets jammed .   The circuit is self explanatory . 555 is wired as an astable multivibrator for a frequency of nearly 38 kHz. This is the frequency at which most of the modern TVs receive the IR beam . The transistor acts as a current source supplying roughly 25mA to the infra red LEDs. To increase the range of the circuit simply decrease the value of the 180 ohm resistor to not less than 100 ohm.

Click Here For More Details

1.5V LED FLASHER

To squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency. A small 1.5 volt alkaline N cell should flash the LED for a full year. It too uses a "charge pump" technique to provide a LED the needed voltage.

Click  Here For More Details

12V to 120V Inverter

Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how "big" a transformer you use for T1. The inverter can be constructed to supply anywhere from 1 to 1000 (1 KW) watts.

5v Regulated Solar Power Supply

The circuit consists of an oscillator transistor and a regulator transistor.
The solar panel charges the battery when sunlight is bright enough to produce a voltage above 1.9v. A diode is required between the panel and the battery as it leaks about 1mA from the battery when it is not illuminated

Click Here For More Details

Door Knock Beeper

In some apartment buildings and homes, not equipped with a door bell, it may be hard to hear someone knocking on the front door.  The circuit below provides a means to activate a loud beeping sound inside, whenever someone knocks on the door from the outside.  The circuit is powered by a 9v battery, which should provide years of service.  An on/off switch allows the device to be turned off if desired. 

Click Here For More Details

3-Pin Fan in 4-Pin Socket

The most recent PC motherboards provide four pin connectors for cooling fans especially for the CPU fan. The older three pin fans are controlled by varying their DC voltage. The fourth pin on the newer connectors supplies a PWM signal to control fan speed. A three pin fan can be plugged into the four pin connector but with its fixed 12 V supply it runs at full speed all the time the PC is switched on.

Click Here For More Deatails       

5 VOLT MOMENTARY OPERATION TOUCH SWITCH

This simple circuit uses a single IC to form a nice touch switch circuit.  A single transistor forms the remote active switch sensor.  Multiple switches can be wired in parallel.  The switch circuit can be located about 500 feet from the control circuit.

Click Here For More Details

40KHz LASER BURST DETECTOR

This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen. It was used as part of a firearm training system. It generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst, modulated at 40KHz. It is very sensitive and could be modified for long-range laser communications.

Click Here For More Detail

Fake Car Alarm Light

Whenever the car’s ignition is turned off, this circuit activates a flashing LED, which can be positioned to appear as an active alarm system.

Click Here For More Detail

1.5V LED FLASHER VERSION A

Judging from the numerous references I have received, this electronic circuit, hobby circuit seems to be rather popular.  Many published circuits which flash LEDs need 3 or more volts. This electronic circuit uses only a single inexpensive C-MOS IC and flashes the LED for a full year on a single 1.5 volt AA alkaline battery cell. The circuit uses a charge pump technique to provide the LED with the needed voltage.  This electronic schematic will only work on red, green and yellow LEDs.  It is not be able to flash white LEDs.

Cell Phone Helper

When your cellular phone receives a call, it begins transmitting even before you answer. The circuit shown in fig.1 detects this signal and can operate a variety of devices referred to as "load".

Click Here For More Detail

Demodulator

The demodulator block diagram below has three major sections that were implemented in this iteration of the design:

 

                                                             

                                                      Click Here For More Detail

 

1) The Mixer,

2) The Filter,

3) The Phase Shift Network

Experimental 1 KHz Synchronous Detector

OverviewThis circuit employs a synchronous demodulator to separate a 1 KHz signal from noise and measures  the amplitude of the 1 kHz signals once a second at about 60 microvolts per count then sends the measurements via an RS-232 interface for further processing or display. An LED on the board also lights when the measured signal exceeds a preset threshold.

Click Here For More Details

Operational Amplifier (Op-Amp) Basics

The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance. The op-amp has a "inverting" or (-) input and "noninverting" or (+) input and a single output. The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts. A simple dual polarity power supply is shown in the figure below which can be assembled with two 9 volt batteries.    

                                                                            

Click Here For More Detail