Thursday, January 31, 2013

Rain Sound Effects Generator circuit

This rain sound effects generator circuit simulates the rain noise and may be used in the field of electronic music and radio shows.
 As a noise source we use a germanium diode that is directly polarized then is amplifier by a single stage amplifier in order to obtain an acceptable audio level.

A high-pass filter with an adjustable lower limit, built with P1 and C3, allow coverage of the entire range of sound effects from light rain and to torrential rain.

The current consumption is low so you can use a 9V battery. Instead of BC107 you can use any NPN transistor.

Rain Sound Effects Circuit Schematic

rain sound effects generator circuit schematic
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Remote control tester circuit jacky March 24 2008 39 Comments Remote control tester


This is a simple remote controller tester circuit  based on infrared sensor IC TSOP 1738. When the IR waves fall on the sensor it output changes to low state.This makes the transistor Q1 ON and LED will blink according to the code contained in the signal. So for press of each button the LED blinks in different ways. This is a good indication of the working of remote.The diode D1drops 0.7 V to give the IC ~ 5V supply from the available 6V . R2 is a current limiting resistance.

Remote Control Tester Circuit Diagram with Parts List .

Remote Control Tester Circuit
Remote Control Tester Circuit Diagram

Notes .

  • Use a 6V battery to power up the circuit.
  • This circuit can be used to test remotes operating in the 38Khz carrier frequency.Almost all remotes fall into this category so no problem.
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Thursday, January 24, 2013

12V to 220V Converter Circuit

This DIY 12V to 220V voltage converter is build with CMOS 4047 that is the main component of this small voltage converter that transforms a 12V DC into 220V AC. 4047 is used as a astable mutivibrator, at pins 10 and 11 will have a symmetrical rectangular signal wich is amplified b 2 Darlington transistors and finally reach the secondary coil of mains transformer ( 2x10V / 60VA ).
At the main voltage converter transformer terminals it will be 220V.
With the help of P1 the output frequency can be adjusted between 50Hz to 400Hz. Although this is not part of any professional dc ac converters it can be used quite effective on some home appliances.

12V to 220V Voltage Converter Circuit Diagram

12V 220V converter
For more DC to AC voltage converters check the related posts.
Check out the tags for more 12 Volts to 220 Volts converters.

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Thursday, January 17, 2013

5 3W Amplifier With Surround System

The AN7147 Dual 5.3-watt Audio Power Amplifier from Panasonic is listed as a ‘replacement type’ so hopefully will be around for some time to come. Together with some extra components, it can represent a simple surround-sound system requiring no opamps or a negative voltage supply. As shown by the circuit diagram the basic stereo amplifier is changed into a surround-sound system by a trick called ‘adding feedback from the opposite channel’. When surround sound is required, the negative feedback signals supplied by C13-R3 and C12-R4 are fed to the inputs of the ‘other’ amplifier. The resulting phase difference causes the surround effect. If surround sound is not required, the effect can be disabled by pressing push-button S1.
Circuit diagram :
Simple_Surround_Amplifier_Circuit_Diagram5.3W Amplifier With Surround System Circuit Diagram
This causes the bistable built around IC2.A and IC2.B to toggle and drive transistors T1 and T2 such that the above mentioned negative feedback signals are effectively shunted to ground. A high-efficiency LED and a 3.3-kΩ series resistor (R14) should be used to make sure the maximum output current of the CMOS 4001 device is not exceeded. The amplifier should not be loaded with impedance's smaller than 3Ω. The AN7147 will typically supply up to 4.3 watts into 4 Ω. The SIL-12 case needs to be cooled wit a small heatsink of about 6 K/W or better. The quiescent current is modest at just 19 mA.
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Tuesday, January 15, 2013

24V lead acid battery charger circuit

This lead acid battery charger circuit is designed in response to a request from Mr.Devdas .C. His requirement was a circuit to charge two 12V/7AH lead acid batteries in series.Anyway he did not mentioned the no of cells per  each 12V battery. The no of cells/battery is also an important parameter and here I designed the circuit assuming  each 12V battery containing 6 cells. When two batteries are connected in series, the voltage will add up and the current capacity remains same. So two 12V/7AH batteries connected in series can be considered as a 24V/7AH battery.

The circuit given here is a current limited lead acid battery charger built around the famous variable voltage regulator IC LM 317. The charging current depends on the value of resistor R2 and here it is set to be 700mA. Resistor R3 and POT R4 determines the charging voltage. Transformer T1 steps down the mains voltage and bridge D1 does the job of rectification. C1 is the filter capacitor. Diode D1 prevents the reverse flow of current from the battery when charger is switched OFF or when mains power is not available.
Circuit diagram.
24V lead acid battery charger circuit

  • Assemble the circuit on a good quality PCB.
  • T1 can be a 230V primary, 35V/3A secondary step down transformer.
  • If 3A Bridge is not available, make one using four 1N5003 diodes.
  • LM317 must be fitted with a heat sink.
  • R2 = 0.85 ohm  is not a standard value. You can obtain it by combining a 6.2 ohm and 1 ohm resistors in parallel.
  • F1 can be a 2A fuse.
  • To setup the charging voltage, power ON  the charger and hook up a voltmeter across the output terminals and adjust R4 to make the voltmeter read 28V. Now the charger is ready and you can connect the batteries.
  • This charger is specifically designed for two 12V/7AH/6 cell lead acid batteries  in series OR a  24V/7AH/12 cell lead acid battery.
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Friday, January 11, 2013

3 band equalizer circuit

This 3 band equalizer circuit is an active filter network for bass, mid and high audio ranges. It is designed around the LM833 opamp from National Semiconductors.
This opamp IC has the following charactersistics: very low noise figure, wide bandwidth
and a relatively high slew rate.

How does the three band audio equalizer works
The output of this 3 way graphic equalizer is designed to be DC coupled, however due to slight DC variations through the 100K potentiometers at the feedback lines of the opamp A2, a coupling capacitor might be needed.
Technical specifications for the 3 band equalizer
The cutoff frequencies:

  • bass range = 200 Hz
  • high range = 2 kHz
The midrange is a bandpass network with a center frequency of 1 kHz.
The maximum equalizer range is about 15 dB. In the middle position of potentiometer, the noise attenuation is about 90 dB with a bandwidth of 1 MHz and a gain of 0 dB. The gain can be changed through R2 using the following formula: Vu = R2/R1.

Audio Equalizer Circuit Diagram

3 band audio equalizer circuit schematic
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