Sunday, February 28, 2016

Gainclone Power Amplifier

Making of Amplifier Gainclone from this list circuit schematic Gainclone Power Amplifier

Gainclone power amplifier

What is Gainclone Amplifier?

Gainclone was cloned from Gaincard amplifier, an amplifier commercial production 47Labs that cost thousands of dollars. Gaincard amplifier using integrated circuit production National LM3875.
In the end, every amplifier made with LM3875, LM 3876, LM3886, LM1875 even called the Gainclone. While many variations of the amplifier Gainclone. From the basic version through the use of buffers and regulated power supply.

LM3886 Gainclone Power Amplifier Schematic

LM3886 Gainclone Power Amplifier

Basically LM3886 has the dynamics and quality of bass best of the four, but the vocal quality and voice clarity worst. Not much we can do to improve vocal quality and clarity of the 3886's. For improving bass performance using this circuit Subwoofer Booster Circuit

LM1875 Gainclone Power Amplifier Schematic

LM1875 Gainclone Power Amplifier

Basically the LM1875 is the most excellent vocal and clarity of voice among the four. But its also the lowest. Wait, 30 watts may not be called low, especially when we are highly sensitive speakers, use the speaker crossover, but from my experience, there is always a feeling of lack of power when I used to use a smaller power amplifier. But I think overall ic LM 1875 is not the caliber of his older brothers.

LM 3875 3876 Gainclone Power Amplifier Schematic

LM 3875 3876 Gainclone Power Amplifier Schematic

3875 and 3876 was principally the same ic, only 3876 plus mute facility. Because the mute function has nothing to do with the quality of the sound, of course logic is clear, more complex circuits will only reduce the sound quality. At least it will complicate manufacture and increase the cost of components.

3875 clear voice, sweet vocals (especially when given FET front). For the quality of bass, we submit his affairs in the power supply.

Why Low Gain for Gainclone Power Amplifier?

The bigger the gain is greater distortion. But the greater the gain, the greater the power, the more detailed the better and control the bass so that it can better driving speaker. Here we choose a gain of about 18 to 20 times. Smaller than that, there could be instability / oscillation.

How Sound Quality?

It's the most important, what about the sound quality? I know this is the most anticipated reader, so I'm happy to explain that this amplifier sounds good once. Bass, treble, vocals, everything sounds detailed and natural. The most interesting thing is the quality of bass that resembles mosfet amplifier.

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Free CAD Software

The ExpressPCB CAD software is very easy to learn and use. For the first time, designing circuit boards is simple for the beginner and efficient for the professional. Best of all, its FREE.
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ExpressPCB 7.3.5

ExpressPCB 7.3.5


Version: 7.3.5
Download ExpressPCB for XP, 2000 , NT, Vista, Windows 7,  Windows 8.1 and Windows 10.
1. Download the setup program.
The ExpressPCBSetup program includes both ExpressSCH for drawing schematics and ExpressPCB for circuit board layout. Download the setup program below.
2. Easy to install.
After downloading, run the ExpressPCBSetup program. Our installation program is very straightforward, but if for any reason you have trouble, please send us a note.
3. Quick start guides get you going fast.
Our software is very simple to use! Even so, we suggest that you quickly read our two short Quick Start Guides. Look in the Help menu of the ExpressSCH program for the Quick Start Guide on drawing schematics. For circuit board design, read the Quick Start Guide found with the ExpressPCB program.
4. Tips for the first time designer.
If you are a beginner to PC board layout, we also suggest that you look over our Tips for Making PC Boards web page.


see full article >>

Saturday, February 27, 2016

LM317 as a Voltage Stabilizer

LM317 Voltage stabilizer schematic diagram

LM317 as a Voltage Stabilizer circuit diagram

Priciple voltage stabilizer

PNP transistor can give to the same condenser with LM317: its output is connected to the condenser as well as the collector of the power transistor. It works so that the current flowing through R1 on it leaves a voltage drop. As long as does not exceed about 300 mA (see here resistance of 2.2 ohms / 0.6W), T1 remains closed and the entire load current flows from the IO. Transgresses If the voltage drop on R1 roughly 0,6-0,7V starts the T1 open and all the current that is above said value gradually takes over. In this circuit can be stabilized supply voltage roughly in stream 15A (depending on the used transistor cooler and the voltage difference between input and output).

Divider R2 / R3 while still providing control of the output voltage. Because the output power transistor is in the collector, which is connected with the housing, it is both active elements screwed to one chiller. A certain disadvantage is that the heat that follows may not radiate integrák must be paid on the transistor, or the cooler will play as wel

12 to 20000 Volt electronic Stun Gun

12V to 20000V inverter circuit diagram STUN GUN. This circuit generates a very high voltage , must be used with caution in order to prevent electric shock . The transformer can produce more than 1000V and eight times the pressure. this circuit using IC 555 to generate pulse.

12 to 20000 Volt electronic Stun Gun Schematic Diagram

12 to 20000 Volt electronic Stun Gun Circuit schematic

Thursday, February 25, 2016

High Quality Audio Amplifier 200 Watt

This high quality power audio amplifier will give you top class quality for loudspeaker 4 – 8 ohm. Frequency range 20-20000Hz, Voltage 24-36V with current max 5A. You need heatsink to keep the transistor from overheating.

Itu use dual polarity power supply to work, then you may use this power supply to supply the circuit.

Schematic diagram:
200 Watt High Quality Audio Amplifier circuit diagram
Component part list:
200 Watt High Quality Audio Amplifier circuit diagram
200 Watt High Quality Audio Amplifier circuit diagram
Top PCB Layout:
200 Watt High Quality Audio Amplifier circuit diagram
200 Watt High Quality Audio Amplifier circuit diagram

200 Watt High Quality Audio Amplifier circuit diagram
Bottom PCB Layout:
200 Watt High Quality Audio Amplifier circuit diagram

See also pre-amplifier circuit to optimize your audio power amplifier : 

And see here for many High Power Audio Power Amplifier

Read more

Simple power saver

This simple power saver circuit is used to save electricity in our homes to avoid spending too much electric use . You can using an Auto Soft Starter for external circuit as function to reduce electricity power.

How it works power saver? 

This circuit of works to filter the AC voltage , and reduce the magnitude of the cosine curve AC current that will be read on the instrument KWH meters. KWH meters will work if there is a load wire passing through a coil of wire sensors to measure the AC current is passed, if the current through a lot of electricity. C1 and C2 worked as a deduction from stamping voltage if the switch is connected, so that equipment or components which enter the voltage was not much shocking.

Simple power saver circuit

Part List simple power saver circuit:

C1,C2 = 100pF / 400V or higher
C3      = 10uF / 400V non polar capacitor
Fuse   = 0.5W
S1      = Switch on/off
Use best quality capacitors
Use the circuit on each item that requires AC power house to besaved using voltage field of electronics goods. Or if you take the trouble to make on each item , then use immediately near the KWH meter, to disconnect to tke their input and issued again on output, should use the box to close the circuit.

Wednesday, February 24, 2016

Circuit of LED Driver High Power

Circuit of LED Driver High Power

High-power LED's: the future of lighting!

but... how do you use them? where do you get them?

1-watt and 3-watt Power LED's are now widely available in the $3 to $5 range, so i've been working on a bunch of projects lately that use them. in the process it was bugging me that the only options anyone talks about for driving the LED's are: (1) a resistor, or (2) a really expensive electronic gizmo. now that the LED's cost $3, it feels wrong to be paying $20 for the device to drive them!

So I went back to my "Analog Circuits 101" book, and figured out a couple of simple circuits for driving power LED's that only cost $1 or $2.

This instructable will give you a blow-by-blow of all the different types of circuits for powering Big LED's, everything from resistors to switching supplies, with some tips on all of them, and of course will give much detail on my new simple Power LED driver circuits and when/how to use them (and i've got 3 other instructables so far that use these circuits). Some of this information ends up being pretty useful for small LED's too

here's my other power-LED instructables, check those out for other notes & ideas

This article is brought to you by MonkeyLectric and the Monkey Light bike light.

Step 1: Overview / Parts

There are several common methods out there for powering LED's. Why all the fuss? It boils down to this:
1) LED's are very sensitive to the voltage used to power them (ie, the current changes a lot with a small change in voltage)
2) The required voltage changes a bit when the LED is put in hot or cold air, and also depending on the color of the LED, and manufacturing details.

so there's several common ways that LED's are usually powered, and i'll go over each one in the following steps.


This project shows several circuits for driving power LED's. for each of the circuits i've noted at the relevant step the parts that are needed including part numbers that you can find at . in order to avoid much duplicated content this project only discusses specific circuits and their pros and cons. to learn more about assembly techniques and to find out LED part numbers and where you can get them (and other topics), please refer to one of my other power LED projects.

See full article High Power LED driver Circuit : instructables 

220V lamp flasher with IC 555

This is 220V 800W lamp flasher circuit directly connected to 220V mains. One or more lamp which has high consumption / power can be used. It is ideal for signage warning or danger, this circuit flickers the lamps.
220V lamp flasher with IC 555 circuit

The work of this circuit is simple. The 400V capacitor, the bridge rectifier, the zener diode and the capacitor 100?F will form the power supply voltage which obtained approx. 9VDC from transformerless power supply design. 

IC 555

The integrated 555 and its annexes components generate a train of pulses applied on the triac optocoupler MOC3021 driven intermittently causing the lamp on and off continuously. The triac may be a 2N6073A or TIC226D. By changing the 100K resistor or 1?F capacitor, then the flashing time will changed too. The rectifier bridge may be four 1N4007 diodes or 400v bridge diode with 1A current. The triac should be mounted on a heat sink to prevent over heating.

Warning!!! The entire circuit operates from 220v mains without insulation so the appropriate safety precautions should be taken to minimize the risk. Build this 220V 800W lamp flasher circuit with your own risk.

Read more

Lithium-ion (Li-ion) battery charger

Lithium-ion (Li-ion) battery charger which built based single chip MAX1879. This is the simple and low cost battery charger for single-cell Li+ battery that does not dissipate power (no heat.

Circuit diagram of Lithium-ion (Li-ion) battery charger

Lithium-ion (Li-ion) battery charger circuit schematic

The MAX1879, in conjunction with the AC linear transformer adapter and a PMOS FET, allows safe and fast charging of a single Li+ cell. The MAX1879 is not only an inductorless required solution, but also the lowest power dissipated solution among single-cell Li+ battery chargers.

The MAX1879 with a current limited linear wall adapter can produce the most economic and efficient solution for the single-cell Li+ off-line cradle charger, with virtually no power loss on the PMOS FET. It can be easily designed for handheld devices or battery packs without excessive power dissipation and heat problems. 

Read detailed explanation about this Lithium-ion (Li-ion) battery charger circuit at

Learn how to make phone charger on motorcycle

About MAX1879:

The MAX1879 single-cell lithium-ion (Li+) battery charger utilizes an efficient pulse-charging architecture to minimize power dissipation in portable devices. This architecture combines the efficiency of switch-mode chargers with the low cost and simplicity of linear chargers. This simple device, in conjunction with a current-limited wall cube and a PMOS transistor, allows safe and fast charging of a single Li+ cell. 

MAX1879 Features:

  • Low Electronic Component Count, No Inductor
  • Simple Design Minimizes Heat
  • 0.75% Accurate Battery Regulation
  • 1.5µA (max) Battery Current Drain with Wall Cube Removed
  • Restart Charging at 4.0V
  • Battery-Full Indicator
  • Safely Precharges Near-Dead Cells
  • Automatic Power-Down when Power Source is Removed
  • Continuous Overvoltage and Overtemperature Protection
  • Charges 1 Cell from as Low as 4.5V
  • Pin-Compatible Upgrade to MAX1679

Sunday, February 21, 2016

5 Band equalizer tone control with 4558

This Graphic equalizer circuit using op-amp 4558-LF353 circuit 5 Channels 2 Octave Graphic Equaliser,easy to make equalizer, because using IC 4558 or 1458 or LF353 (nice)
If you are seeking Graphic Equalizer Circuit at can fine decorate the sound of music has full frequency sound section. 

5 Band equalizer tone control with 4558 specification

As a result try out group this circuit before. May don’t be defeated.Cut at frequencies of 50Hz, 200HZ,800Hz,3.2kHz and 12kHz. Supply voltage may be anything from -15V GND -15V for IC 4558. Besides I still lead model PCB try build can be usable easy increasingly sir.
5 Band equalizer tone control with 4558

Source : eleccircuit

Monday, February 15, 2016

Simple Amplifier with Bass-Boost

High Quality, very simple design, No preamplifier required
This design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9.5 – 11.5W range, as the supply rails cannot exceed ±18V. As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses. The bass lift curve can reach a maximum of +16.4dB at 50Hz. In any case, even when the bass control is rotated fully counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB at 400Hz, +4.7dB at 100Hz and +6dB at 50Hz (referred to 1KHz).
10W Bass Boost Amplifier Circuit Diagram

10W Bass Boost Amplifier Circuit Diagram

P1_____________22K Log.Potentiometer (Dual-gang for stereo)
P2_____________100K Log.Potentiometer (Dual-gang for stereo)
R1_____________820R 1/4W Resistor
R2,R4,R8_______4K7 1/4W Resistors
R3_____________500R 1/2W Trimmer Cermet
R5_____________82K 1/4W Resistor
R6,R7__________47K 1/4W Resistors
R9_____________10R 1/2W Resistor
R10____________R22 4W Resistor (wirewound)
C1,C8__________470nF 63V Polyester Capacitor
C2,C5__________100µF 25V Electrolytic Capacitors
C3,C4__________470µF 25V Electrolytic Capacitors
C6_____________47pF 63V Ceramic or Polystyrene Capacitor
C7_____________10nF 63V Polyester Capacitor
C9_____________100nF 63V Polyester Capacitor
D1______________N4148 75V 150mA Diode
IC1_____________NE5532 Low noise Dual Op-amp
Q1_____________BC547B 45V 100mA NPN Transistor
Q2_____________BC557B 45V 100mA PNP Transistor
Q3_____________TIP42A 60V 6A PNP Transistor
Q4_____________TIP41A 60V 6A NPN Transistor
J1______________RCA audio input socket
Power Supply Circuit Diagram

Power Supply Circuit Diagram

Power supply parts:
R11______________1K5 1/4W Resistor
C10,C11__________4700µF 25V Electrolytic Capacitors
D2_______________100V 4A Diode bridge
D3_______________5mm. Red LED
T1_______________220V Primary, 12 + 12V Secondary 24-30VA Mains transformer
PL1______________Male Mains plug
SW1_____________SPST Mains switch
  • Can be directly connected to CD players, tuners and tape recorders.
  • Schematic shows left channel only, but C3, C4, IC1 and the power supply are common to both channels.
  • Numbers in parentheses show IC1 right channel pin connections.
  • A log type for P2 will ensure a more linear regulation of bass-boost.
  • Do not exceed 18 + 18V supply.
  • Q3 and Q4 must be mounted on heatsink.
  • D1 must be in thermal contact with Q1.
  • Quiescent current (best measured with an Avo-meter in series with Q3 Emitter) is not critical.
  • Set the volume control to the minimum and R3 to its minimum resistance.
  • Power-on the circuit and adjust R3 to read a current drawing of about 20 to 25mA.
  • Wait about 15 minutes, watch if the current is varying and readjust if necessary.
  • A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of J1, P1, C2, C3 &C4;. Connect C9 to the output ground.
  • Then connect separately the input and output grounds to the power supply ground.
Technical data:
Output power:
10 Watt RMS into 8 Ohm (1KHz sinewave)
115 to 180mV input for 10W output (depending on P2 control position)
Frequency response:
See Comments above
Total harmonic distortion at 1KHz:
0.1W 0.009% 1W 0.004% 10W 0.005%
Total harmonic distortion at 100Hz:
0.1W 0.009% 1W 0.007% 10W 0.012%
Total harmonic distortion at 10KHz:
0.1W 0.056% 1W 0.01% 10W 0.018%
Total harmonic distortion at 100Hz and full boost:
1W 0.015% 10W 0.03%
Max. bass-boost referred to 1KHz:
400Hz = +5dB; 200Hz = +7.3dB; 100Hz = +12dB; 50Hz = +16.4dB; 30Hz = +13.3dB
Unconditionally stable on capacitive loads

High Voltage Converter

The circuit shows one way of obtaining a voltage of 90V from a 1.5V battery supply the  High Voltage Converter. The LT1073 switching regulator from Linear Technology ( operates in boost mode and can work with an input voltage as low as 1.0 V. The switching transistor, which is hidden behind connections SW1 and SW2, briefly takes one end of choke L1 to ground. A magnetic field builds up in the choke, which collapses when the transistor stops conducting: this produces a current in diode D1 which charges C3. The diode cascade comprising D1, D2, D3, C2, C3 and C4 multiplies the output voltage of the regulator by four, the pumping of C2 causing the voltage developed across C4 via C3, D2 and D3 to rise.

High Voltage Converter Circuit Schematic

 High Voltage Converter Schematic diagram

Circuit work

Finally, the regulator control loop is closed via the potential divider (10 MΩ and 24 kΩ). These resistors should be 1 % tolerance metal film types. With the given component values, fast diodes with a reverse voltage of 200 V (for example type MUR120 from On Semiconductor and a choke such as the Coilcraft DO1608C-154 ( an output voltage of 90 V will be obtained. The output of the circuit can deliver a few milliamps of current.

DIY 220VAC Flashing Lights

Especially designed for Christmas tree lamps, Replaces old thermally-activated switches

This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1, R2 & C1. To change flashing frequency do not modify R1 and R2 values: set C1 value from 100 to 2200µF instead.
Best performances are obtained with C1= 470 or 1000µF and R4= 12K or 10K. Due to low consumption of normal 10 or 20 lamp series-loops intended for Christmas trees (60mA @ 230V typical for a 20 lamp series-loop), very small and cheap SCR devices can be used, e.g. C106D1 (400V 3.2A) or TICP106D (400V 2A), this last and the suggested P0102D devices having TO92 cases. 
220VAC Flashing Lights circuit schematic

Parts 220VAC Flashing Lights circuit

R1 = 100K
R2 = 1K
R3 = 470R
R4 = 12K
R5 = 1K
R6 = 470R
Q1 = BC327
Q2 = BC337
D1 = 1N4007
D2 = 1N4007
D3 = 1N4007
D4 = 1N4007
D5 = P0102D (SCR)
C1 = 1KµF-25V
PL1 = Male Mains plug
SK1 = Female Mains socket

Important Note:

For proper operation it is absolutely necessary to employ high Gate-sensitive SCRs.
If you are unable to find these devices you can use Triacs instead. In this case the circuit operates also with relatively powerful devices. A recommended Triac type is the ubiquitous TIC206M (600V 4A) but many others can work.
Please note that, in spite of the Triac, diode bridge D1-D4 is in any case necessary.
Warning! The device is connected to 230Vac mains, then some parts in the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged and enclose it in a plastic box.
Source: Red Free Circuit Design

Switching Power Supply Soft Start

Switching power supply whose output voltage is appreciably lower than its input voltage has an interesting property: the current drawn by it is smaller than its output current. However, the input power (UI) is, of course, greater than the output power. There is another aspect that needs to be watched: when the input voltage at switch-on is too low, the regulator will tend to draw the full current. When the supply cannot cope with this, it fails or the fuse blows. It is, therefore, advisable to disable the regulator at switch-on (via the on/off input). until the relevant capacitor has been charged.
When the regulator then starts to draw current, the charging current has already dropped to a level which does not overload the voltage source.

Circuit diagram Switching power supply :

Switching power supply soft
Soft Start Circuit For Switching Power Supply

The circuit in the diagram provides an output voltage of 5 V and is supplied by a 24 V source. The regulator need not be disabled until the capacitor is fully charged: when the potential across the capacitor has reached a level of half or more of the input voltage, all is well. This is why the zener diode in the diagram is rated at 15 V. Many regulators produced by National Semiconductor have an integral on/off switch, and this is used in the present circuit. The input is intended for TTL signals, and usually consists of a transistor whose base is accessible externally. This means that a higher switching voltage may be applied via a series resistor: the value of this in the present circuit is 22 kΩ. When the voltage across the capacitor reaches a level of about 17 V, transistor T1 comes on, whereupon the regulator is enabled.
Source: National Semiconductors

Sunday, February 14, 2016

6A / 0-28V Variable Power Supply

The following diagram is the schematic diagram of variable power supply which will deliver 0 to 28V output voltage at 6A or 8A electric current. 6A regulated variable power supply circuit

6A / 0-28V Variable Power Supply

Components List 6A / 0-28V Variable Power Supply Circuit:

R1 = 2K2 Ohm 2,5 Watt
R2 = 240 Ohm
R3,R4 = 0.1 Ohm 10 Watt
R7 = 6K8 Ohm
R8 = 10K Ohm
R9 = 47 Ohm 0.5 Watt
R10 = 8K2 Ohm
C1, C7, C9 = 47nF
C2 = 4700uF/50v – 6800uF/50v
C3, C5 = 10uF/50v
C4, C6 = 100nF
C8 = 330uF/50v
C10 = 1uF/16v
C11 = 22nF D1…D4 = four MR750 (MR7510) diodes (MR750 = 6 Ampere diode) or 2 x 4 1N5401 (1N5408) diodes.
D5 = 1N4148, 1N4448, 1N4151
D6 = 1N4001
D10 = 1N5401
D11 = LED
D7, D8, D9 = 1N4001
TR = 2 x 15 volt (30volt total) 6+- Ampere
IC1 = LM317
T1, T2 = 2N3055
P1 = 5k
P2 = 47 Ohm or 220 Ohm 1 Watt
P3 = 10k trimmer
F1 = 1 Amp
F2 = 10 amp

Circuit Description:

This is an easy to make power supply that has reliable, clear and regulator 0 to 28 Volt 6/8 Amp output voltage. By making use of two 2N3055 transistor, you’ll get two times the amount of electric current.
Although the 7815 power regulator may kick in on short circuit, overload and thermal overheating, the fuses in the main section of the transformer and the fuse F2 at the output will safe your power supply. The rectified voltage of: 30 volt x SQR2 = 30 x 1.41 = 42.30 volt measured on C1. So all capacitors should be rated at 50 volts. Caution: 42 volt will be the voltage that could be on the output if 1 of the transistors ought to blow.
P1 lets you ‘regulate’ the output voltage to something in between 0 and 28 volts. The LM317 lowest voltage is 1.2 volt. To have a zero voltage on the output I’ve place 3 diodes D7,D8 and D9 around the output with the LM317 towards the base with the 2N3055 transistors. The LM317 optimum output voltage is 30 volts, but using the diodes D7,D8 & D9 the output voltage is approx 30v – (3x 0.6v) = 28.2volt.
Adjust your build-in voltmeter using P3 and, of course, a fine digital voltmeter is better solution.
P2 will let you to control the limit with the optimum available electric current in the output +Vcc. When utilizing a 100 Ohm / 1 watt varistor the current is limited to approx. 3 Amps @ 47 Ohm and +- 1 Amp @ 100 Ohms.
6A / 0-28V Variable Power Supply source:

Friday, February 12, 2016

Low Noise - Distortion Pre-Amp and Tone Control

This is a low noise and distortion pre-amplifier and tone control circuit in one module. Using a special IC TDA1524A, this simple circuit is easy to build and will drive most of power amplifier. See also Subwoofer Booster Circuit.

Schematic diagram low noise and distortion pre-amplifier and tone control circuit:

low noise and distortion pre-amplifier and tone control circuit

Pre-Amp + Tone Control with TDA1524A circuit diagram

Pre-Amp + Tone Control Components List:

R1, R2__________________ 220R
R3, R4__________________ 4K7
R5______________________ 2K2
R6______________________ 1K
C1, 2, 7, 8, 17_________ 10 uF CAP
C3, 4___________________ 47 nF
C5, 6___________________ 15 nF
C9______________________ 220 nF poly
C10_____________________ 100 uF 25V
C11, 12, 13, 14, 16_____ 100 nF
C15_____________________ 1000 uF 35V
C18, 19_________________ 10 nF
IC1_____________________ TDA 1524A
IC2_____________________ LM 7812
P1______________________ 50k linear switch pot
P2, 3, 4________________ 50k linear pot
X1, 2, 3, 4_____________ RCA jack
D1______________________ Diode 1N4004
L1______________________ Red LED

Circuit Works:

All signal processing is done within the TDA1524A by voltage controlled amplifiers and voltage controlled filters. The IC provides a fixed voltage (~ 3.8V DC) at pin 17, and this is used by all the variable resistors to provide an adjustable DC voltage to the appropriate control pins.
Current sensing is used to provide a flat response when R5 is connected to pin 17, and a loudness contour when disconnected. 100 nF capacitors are used on each pot to decouple any AC signals from the control inputs. 10 uF capacitors are used to couple both input and output audio signals whilst blocking DC. R1 and R2, are to ensure stability with capacitive loads. R3 and R4 make sure there are no DC spikes at the output sockets if the load is switched. C3 and C4 control the loudness contour. C5 and C6 control the treble turn-over frequency. C18 and C19 have been added to roll off the gain above 70 kHz. Low volume settings coupled with treble boost was causing HF instability in some instances. This should no longer be a problem.

C15, 16, 17 provide power supply filtering. D1 provides protection in case of incorrect supply polarity. The LED is a power on indicator and may be omitted if not required, or preferably mounted on the enclosure. If you are not using a switch pot, you can connect an external switch across the P1 switch pins, or connect a wire link there and switch the power supply.

The power supply is critical to the noise performance of the pre-amp. An on board regulator is provided to reduce mains hum. If you wish to use it with a car or other 12V battery, then you should omit the 7812 regulator, and place a wire link between the regulator input and output pin positions on the PC board. Do not short to earth! This will be necessary because the regulator must have an input voltage at least 2-3V greater than it”s output, for it to maintain regulation. However the regulator will not be necessary with a battery supply.

If using a plug pack, it”s output voltage should be 15 to 18V DC. Because most plug packs have poor regulation, one rated at 12V DC will often be around 15V when lightly loaded. The current drain of the pre-amp is less than 50 mA, so many 12 V unregulated supplies may be adequate if you have one. Replace D1 with a wire link if necessary, making sure you have the supply polarity correct!
If you are using a 15-20V supply for your power amplifier, you can use that as your pre-amp supply as well. Make sure you test the voltage first in all cases.

Thursday, February 11, 2016

How to make Phone Battery Charger

The following diagram is a simple mobile phone battery charger circuit. The design is simple, easy to build and inexpensive. It use LM78xx regulator to make regulated and stable output voltage. Simple Mobile Phone Battery charger circuit diagram Mobile phone chargers offered in the marketplace are quite expensive.

How to make phone battery charger

Charging Phone Battery

The 220-240V AC mains source is stepped down to 9V AC by transformer X1. The transformer output is rectified by diodes D1 through D4 connected in bridge configuration and the positive DC source is straightly wired to the charger”s output contact, while the negative terminal is connected through current limiting resistor R2.
LED2 operates as being a power indicator with resistor R1 serving as the current limiter and LED3 signifies the charging status. While in the charging period, about 3 volts drop happens across resistor R2, which switches on LED3 through resistor R3.

How It Battery charging works

The circuit shown right here shows up as a low-cost option to charge cell phones or battery packs having a rating of 7.2 volts, for example Nokia 6110/6150. The 220-240V AC mains source is stepped down to 9V AC by transformer X1. The transformer output is rectified by diodes D1 through D4 connected in bridge configuration and the positive DC source is straightly wired to the charger”s output contact, while the negative terminal is connected through current limiting resistor R2. LED2 operates as being a power indicator with resistor R1 serving as the current limiter and LED3 signifies the charging status.
While in the charging period, about 3 volts drop happens across resistor R2, which switches on LED3 through resistor R3. An external DC supply source (for example, from a automobile battery) may also be applied to energise the charger, in which resistor R4, after polarity protection diode D5, limits the input current to a secure value. The 3-terminal positive voltage regulator LM7806 (IC1) delivers a fixed voltage output of 7.8V DC because LED1 interconnected in between the common terminal (pin 2) and ground rail of IC1 increases the output voltage to 7.8V DC. LED1 also acts as being a electrical power indicator for the external DC source. After building the circuit on a veroboard, enclose it inside a appropriate cabinet. A little heatsink is highly recommended for IC1.

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70Watt Mosfet Power Amplifier

There are possible alternative input stage transistors, the Toshiba 2SA970BL and 2SC2240BL, which appear to be good substitutes for the Hitachi 2SA1085E and 2SC2547E. The ‘BL’ suffix is the high gain group. Alternatives for the Sanyo 2SC2911 and 2SA1209 are the Toshiba 2SC3423 and 2SA1360.
70Watt Mosfet Power Amplifier

This 70W power amplifier is designed for quality rather than quantity, and if much higher power is really needed there are other more suitable design approaches.
This is an awesome amplifier circuit, and this is the older version (MJR7-Mk3). There is new version released (MJR7-Mk5) for better quality and performance, just go to THIS PAGE for complete circuit explanation.

Simple Dew sensor circuit

This is a simple and low cost dew sensor circuit that can be used to switch off any gadget automatically in case of excessive humidity. Dew (condensed moisture) adversely affects the normal performance of sensitive electronic devices.

Dew sensor circuit
click view larger:Simple Dew sensor circuit

Dew (condensed moisture) 

The main part of this circuit is a low cost dew sensor element (resistor type). Although dew sensor elements are widely used in video cassette players and recorders, these may not be easily available in local market. However, the same can be procured from authorised service centres of reputed companies. The author used the dew sensor for FUNAI VCP model No. V.I.P. 3000A (Part No:6808-08-04, reference no. 336) in his prototype. In practice, it is observed that all dew sensors available for video application possess the same electrical characteristics irrespective of their physical shape/size, and hence are interchangeable and can be used in this project.

Use  dual op-amp IC LM358N 

This simple and low cost dew sensor circuit is basically a switching type circuit made with the help of a popular dual op-amp IC LM358N which is configured here as a comparator. (Note that only one half of the IC is used here.) Under normal conditions, resistance of the dew sensor is low (1 Kohm or so) and thus the voltage at its non-inverting terminal (pin 3) is low compared to that at its inverting input (pin 2) terminal. The corresponding output of the comparator (at pin 1) is accordingly low and thus nothing happens in the circuit.

When humidity exceeds 80%, the sensor resistance increases rapidly. As a result, the non-inverting pin becomes more positive than the inverting pin. This will push up the output of IC1 to a high level. As a consequence, the LED inside the optocoupler is energised. At the same time LED1 provides a visual indication. The optocoupler can be used to any electronic device for switching purpose.
This circuit uses a low voltage, low current power supply unit. The diode D1, resistors R8 and R6 and capacitor C1 do the job. This simple power supply module obviates the requirement for a bulky and expensive step down transformer.