Friday, January 4, 2013

Graphic Equalizer Schematic 10 band Mono

Graphic Equalizer Schematic
This really is ten band graphic equalizer for 1 channel (mono) audio program. You will need build 2 similiar circuits for 2 channel (stereo) audio method. This equalizer construct depending on TL074 low sound JFET op-amp that will give you top quality audio output.
Graphic Equalizer Schematic 10 band Mono Part List:

R1....20= 10KohmsC4= 10nF polyesterC18= 68pF polysterine
R21....40= 1MohmsC5= 47nF polyesterC19= 360pF polysterine
R41= 10KohmsC6= 4.7nF polyesterC20= 36pF polysterine
R42= 1KohmsC7= 22nF polyesterC21= 4.7uF polyester
R43.....52= 2.2KohmsC8= 2.2nF polyesterC22-23= 33pF polysterine
R53.....62= 47KohmsC9= 12nF polyesterC24= 10uF 25V
R63-64-66-67= 47KohmsC10= 1.2nF polyesterC25-26= 47uF 25V
R65= 10KohmsC11= 5.6nF polyesterC27...32= 47nF polyester
R68-69= 47 ohms 1/2WC12= 560pF polysterineIC1...3= TL074
RV1....10= 100Kohms lin FADERC13= 2.7nF polyesterS1= 2X4 SW for stereo
RV11= 10Kohms log.C14= 270pF polysterine
C1= 180nF polyesterC15= 1.5nF polyester
C2= 18nF polyesterC16= 150pF polysterine
C3= 100nF polyester C17= 680pF polysterine

Mosfet Audio Amplifier 20W

Mosfet Audio Amplifier 20W

Mosfet Audio amplifier 20W schematic
This audio power amplifier makes use of two complementary MOSFETs (IRF9520 and IRF520) to supply up to 20W into eight O speaker. A TL071 op amp is utilized as an input amplifier. The MOSFETs should certainly be heatsinked having a heatsink of far better than 50C/W capability. THD is less than 0.15% from 100Hz to 10KHz.



A wonderful diy gsm jammer or cellular mobile phone jammer schematic diagram for use only in GSM1900 with frequency from 1930 MHz to 1990 MHz. The GSM1900 cellular cell phone network is made use of by USA, Canada and most of the nations in South America. This cellular phone jammer isn't applicable for use in Europe, Center East, nor Asia. The GSM jammer circuit could block mobile mobile phone signals which operates on GSM1900 band, also identified as DCS.

NE 555 & LM 567 Remote Control Circuit

Remote control circuit consists of two parts, one is transmitter and the other is receiver. A simple diagram is schematic remote control. The transmitter circuit’s transmitter IC is controlled by NE555. Receiver circuit works by the signal emitted frequency which is emitted by that transmitter circuit. Transmitted signal frequency must be equal to the frequency decoder of the receiver circuit. The NE 555 generated frequency is same that receive frequency of IC LM 567. 

The output frequency of the transmitter circuit is f,

f = 1.44/(Ra+2Rb)C


           The resistor R1 is a receiver variable to facilitate the process of tuning. The system works well when the circuit is ready. The first step is tuning by way of the transmitter is turned on continuously, while the receiver R1 to set the value to be able to detect the signal transmitter. The second part is the receiver is controlled by LM 567. The following is a schematic drawing recipient.

f = 1 / (1.1 xR1xC1)

This frequency depends on the value of R1 and C1.

In the picture on top of each channel is designed with a different frequency. By considering the bandwidth of the frequency detection signal LM 567, inter-frequency channels should have a big enough difference, let’s try with a difference of 5 KHz.

BC548 Heat Sensor Diagram Circuit

BC548 Heat Sensor Circuit


Heat sensor circuit can be used to control any device using heat sensor. In this circuit a thermistor and a resistance is connected in series. This arrangement makes a potential divider circuit. Here the thermistor is Negative Temperature Coefficient type. So when the room temperature is increased its resistance decreases simultaneously and more current flows through the resistor and the thermistor. We find more voltage at the junction of the resistor and the thermistor.

Our thermistor resistance value is 110 ohms. Suppose the resistance value becomes 90 ohms after heating the 110 ohms thermistor. Then the voltage across one resistor of the voltage divider circuit equals the ratio of that resistor’s value and the sum of resistances of the voltage across the series combination. This is the concept of voltage divider. The final output voltage of the voltage divider circuit is now applied to the npn transistor (BC548) through the base resistor (3.3K ohms). Here the emitter resistor is replaced with a zener diode. Emitter voltage is maintained at 4.7volt with the help of zener diode. This voltage is used to compare voltage. Transistor conducts when base voltage is greater than the emitter voltage. Transistor conducts if it gets more than 4.7volt of base voltage. Then the circuit is completed through buzzer and it gives sound.

Basic Sound Generator Circuit Diagram

This is so important circuit for the persons who came to this field recently.Here I have used common IC NE555.According to the pules (Frequency) of the IC We can generate the sound.You can change the speed of the sound by adjusting R2.This circuit operates with 5V.

# Note
# Don't give over 5V
# Build this circuit on a PCB
# Don't give the much heat to the IC NE555


(VHF) TV Transmitter circuit diagram

Most of people ask TV transmitters.So Today I'm going to give you a very useful circuit diagram.By using this circuit you can send your signals 75m to 100m.This circuit diagram is not my own circuit one of my friends gave me this.I suppose you guys also can send your own circuit diagrams for us.Then we can publish them through our website.Here They have used common transistor BC 108 If you are unable to find this transistor you can use equal transistors like Bc337 2n2222 Bc 546

# To make L1 wound 6 turns of #24 enameled wire on a 10mm air former for frequency 60 - 80 MHz For 150 - 180 MHz wound 4 turns and for 180 - 200MHz wound 2 turns.

# This circuit operates with 9V power supply
# When you build this circuit you have to build this on a little space.
# The power of this circuit is 80mW
# use a pcb to build this circuit diagram.
# This is only for educational purpose.We can bear any responsibility of this If you misused this.
# This circuit transmit only video signals .If you want to send sound signals you can use an audio transmitter


20 Watt Class A Power Amplifier Circuit

A single-ended Class-A amplifier is essentially one where there is only one active driven output device. The passive "load" may be a resistor, an inductor (or transformer) or - as in this amplifier - a current sink. Of the three basic options, the current sink offers the highest linearity for the lowest cost, so is the ideal choice.

20W class A power amplifier circuit

Some esoteric (some might say idiosyncratic) designs use inductors or 1:1 transformers, but these are bulky and very expensive. Unless made to the utmost standards of construction, they will invariably have a negative effect on the sound quality, since the losses are frequency dependent and non-linear.

This amp uses the basic circuitry of the 60W power amp (see Index), but modified for true Class-A operation - it should be pretty nice! This amp has been built by several readers, and the reports I have received have been very positive.

With simulations, everything appears to be as expected, but although I have yet to actually build it and test it out thoroughly, no-one has had any problems so far. Using +/-20 Volt supplies - either conventional, regulated or using a capacitance multiplier, it should actually be capable of about 22 W before clipping, but expect to use a big heatsink - this amp will run hot.

230V Flasher Circuit diagram

This circuit operates with can use this circuit to decorate your parties.I think this will be a wonderful circuit to you all. Here DIAC ER 900 and Triac BTW 11-400.

230V Flasher Circuit diagram

230V Flasher Circuit diagram

# Be careful when you deal with 230V
# Build this circuit on a PCB
# Use only mentioned values.


Eight Band Sub-Woofer Graphic Equaliser

Your sub is installed and set up as best you can, but you can't quite get it to sound right. Some frequencies are too prominent, while others seem subdued. If this sounds familiar, then this equaliser is what you need to fix it. It is not a panacea, and will not cure an impossible room, but the majority of lumps and bumps in the subwoofer response will respond very well to an equaliser as described here.

The unit is an 8 band variation on the expandable equaliser described in the Project Pages, and is dedicated to its task. Boards can be stacked to get more bands if desired, but the arrangement shown will be quite sufficient for most installations.

Eight Band Sub-Woofer Graphic Equaliser

Photo of Completed P84 Board

The equaliser is a constant Q design, so unlike most "ordinary" equalisers, it does not have a very low Q at low settings of boost and cut. This is a major problem with the standard (graphic) equaliser circuit, and is completely avoided by the constant Q version. Using the Multiple Feedback Bandpass design, these filters can be designed for any (reasonable) frequency and Q desired. As a 1/3 Octave equaliser, the filter Q should be 4.3, but I have deliberately lowered this to 4 for this design to allow a little overlap.

While there will always be "that" room which defies all attempts to make anything sound halfway decent, this EQ will dispose of the majority of problems likely to be encountered.

Diagram Fluorescent Tube Basics

While they have been with us for many years, fluorescent lamps remain somewhat mysterious to most people. This isn't really surprising, since their operation isn't simple. The tube itself contains a mixture of gases, but the active ingredient is mercury. When operated as an arc, mercury vapour emits a vast amount of short-wave ultraviolet light. This is invisible, but phosphors on the inside of the tube itself fluoresce when struck by UV, and are designed to emit visible light. Most of the remaining UV light is absorbed by the glass, which is opaque to ultraviolet (this is why you can't get a suntan from behind a glass window). Refer to Figure 1 to follow the explanation. This also shows a representation of the fitting that was used for the illumination tests. For all tests, only the centre tube was installed, with the others removed to ensure that each lamp was operating under near identical conditions.

Fluorescent Tube Basics

Figure 1 - Wiring Diagram For a Conventional "Troffer" (Fluorescent Light Fitting)

In order to start the arc inside the tube, a starter is used. This is a small neon lamp, with a bimetallic strip contact mechanism built in. When power is first applied, the neon conducts a small current - enough to heat the bimetallic strip, and this causes the switch to close. Once closed, current flows through the filaments at each end of the tube via the ballast, bringing them to working temperature. The ballast limits the current to a safe value. The filaments themselves are fairly rugged, and are typically around 2 Ohms resistance each.

While the switch in the starter is closed, there is no current flow through the neon gas in the starter. The bimetal strip cools and the contacts open. When current drawn through an inductor is suddenly interrupted, a high voltage is generated as the magnetic field collapses. This high voltage will (hopefully) strike the arc in the tube. As most people will have noticed, fluoros usually flicker a few times when turned on. This is usually because the initial strike is insufficient to maintain the arc because the gas temperature is too low. After a few strikes, the temperature is high enough that the arc maintains itself. Maximum light output is usually not achieved for around 5 minutes, but the difference is not very noticeable with tubes in reasonably good condition.

Once the arc is struck (and maintained), the ballast has a new task. An arc has negative resistance, so as the voltage across the tube falls, the current increases. The ballast limits the current to a safe value, as determined by the tube's ratings. With a continuous arc, the voltage across the tube is too low to allow the neon gas in the starter to conduct, so the starter is effectively bypassed. Old tubes will often be unable to maintain an arc, and this is why they flash and flicker, with the starter constantly opening and closing because the arc is not self-sustaining. Since AC is applied to the tube, the arc actually stops and re-strikes on each half cycle, causing the light to flicker at 100 (or 120) Hz. This is normally not visible, but a tube at the end of its life may only conduct fully in one direction. This causes a 50/60Hz flicker that is often visible and annoying to some people.

Because the ballast is an inductor, it should dissipate no power, but this can never be the case in reality. Inductors are wound with copper wire, which has resistance. If nice thick wire were used, this resistance could be minimised, but to do so is very expensive. A compromise is reached where ballast losses are deemed "reasonable", and cause the temperature rise due to power loss to remain within allowable limits. New regulations will soon specify the maximum allowable power loss in ballasts, which will see a return to larger (and more expensive) types than we commonly see today.

Finally, a capacitor is (or should be) installed in parallel with the incoming mains. This is sized to suit the ballast inductance and supply frequency. The capacitive reactance of the PFC (Power Factor Correction) cap should exactly balance out the inductive reactance of the ballast. If this is done properly, the power factor will be 1 - a perfect result. This cannot happen with a fluorescent lamp though, because the current drawn is not linear. The voltage across the tube is a reasonable approximation to a squarewave because of the arc characteristics, and the maximum achievable power factor is normally around 0.9 (90%). Typical fittings manage 0.85 or so (some are better than others).

This means that the current drawn from the mains will be 10% higher than necessary to produce the lamp's rated power. This means that for a 36W fluorescent lamp, the minimum attainable current will be around 190mA at 230V because of ballast losses. The ideal current (if power factor correction were perfect) would be 174mA, allowing for a total typical load of 40W.

Fluorescent Tube Basics

Figure 1A - Wiring Diagram For a "Lead-Lag" Fluorescent Fitting

For many commercial and industrial installations, the 'lead-lag' circuit shown above is common. By including the power factor correction cap in series with one of the ballasts, the power factor is brought to around 0.85 as with the approach shown above, but the capacitor is smaller and thus cheaper than would be the case if the ballasts were in parallel.

Note that where 120V (60Hz) mains voltages are used, you may find that ballast is actually an auto-transformer. This is used because the voltage is not quite high enough to ensure reliable operation, and the auto-transformer configuration boosts the voltage. Figures 1 and 1A are for fittings operating from 220-230V, which need no voltage boost for normal operation. Predictably, the circuits for auto-transformer ballasts are different from those shown here, but similar techniques are used.

Circuit diagram Long time LED Flasher

The special thing of this circuit is this circuit can light up a LED more than the normal time.Sometimes it will light up our LED more than one I suppose this would be a good news for you guys.Here I have used very common Transistor 2N3904.When I was making this circuit I turned about  20 turns around the toroid. the wire was a small circuit wire.   


# Build this circuit on a PCB
 # Don't use more than 1.5V

Simple Touch Switch diagram

This is a simple touch circuit diagram.I think you can use this for many purposes.I have used this circuit as a security circuit device.Here I have used very common Transistors   2N 5458 N and 2N2222 to gain the signal .2N3906 Transistor work as a switch here.

# Build this circuit on a PCB
# Use a copper plate to touch senseer 
# Don't supply more than12V


Automatic light activated switch circuit

The circuit can be used for switching OFF a particular lamp or group of lamps in response to the varying ambient light levels. The unit once built can be used for switching OFF a lamp when dawn breaks and switching it ON when dusk sets in. The power supply is a standard transformer, bridge, capacitor network, which supplies a clean DC to the circuit for executing the proposed actions.

Automatic light activated switch circuit

Automatic light activated switch circuit schematic

The LDR must be placed outside the box, meaning its sensing surface should be exposed toward the ambient area from where the light level is required to be sensed. The circuit can be used as an automatic street light controller system or a simple light activated switch.

TV Diagram remote tester

Sometimes you are unable to check whether your TV remote is working or not.Not only T.V remote you can check any IR signals.Here I have used very common  transistor BC 558  


3 in 1 FlashLight Circuit Diagram

Want to avoid the problem of carrying three different flashlights to perform a test? Why don’t you try integrating Ultra Violet, Infra Red and visible light together in one flashlight? Read on to know more about this.

3 in 1 FlashLight Circuit

The multi-tasking flashlight is basically composed of a metallic case, a switch, cables and connections, four 9V batteries and three different LED heads that provide the desired light beam. For the construction of this flashlight, LedEngin’s LZ4-40 is recommended. This comes with a very wide wavelength that includes infra red and ultra violet light. Distinct visible light color temperature can also be found

The first step is to build the body of the flashlight, using an aluminum tube. Next come the drilling and cutting for switches and covers. Once the body is finished, the work on the constant current driver should be completed, adding the proper terminals for the batteries and the base for the LED heads.

3 in 1 FlashLight Circuit

Once all the power source wiring is completed and insulated with heat shrink tubing, the LED heads are assembled and connected. These are basically composed of an aluminum cap. The LED base and the power source connections come from the batteries.

12V Battery Checker Circuit

This is a 12V battery checker circuit that uses 3 LEDs that light up at their respective voltages. The red LED lights up when the battery voltage is between 8 to 10V, the orange one at voltages between 10.5V to 12V and the green one when the battery voltage is above 12.5V.This is a tried and tested battery checker circuit using one NPN and one PNP transistor. A PCB is given along with the schematic.




Laptop Power Supply Diagram for Car

Laptops today are the what is called notebook computers, which now is becoming popular. Laptops can be brought into the bag making it suitable for business trips. And even as the “home entertainment center” laptop is more convenient, because it takes a little space. However, in my opinion, there is one very important which become shortcomings – most laptops which powered by an electric voltage of 19V, making it impossible for them to direct the power to an integrated network vehicle (12-14V). It is very important, especially when laptop battery capacity is not more than two hours in active mode. And what if you, at some object in the whole day want to process some data, but no other useful sources of electricity?

This is a description of the relatively simple psu laptop circuit adapter (laptop DC-DC converter), which increases the voltage-board vehicle network to 19V, needed to supply the laptop. And maintain this voltage stable.

The adapter is based on chip LM3524, which is a high-frequency switching DC-DC converter with pumped inductance and output current up to 200mA, the output current which, in this scheme, will increased to 3.5-4A using a powerful transistor switch (on transistors VT1 and VT2).

Consider the circuit carefully. Voltage on-board vehicle network goes to supply circuit and output circuits D1 through key fuse F1 and low-resistance wire resistor R6, mitigating start the generator and the circuit operates in overload protection. Current consumption chip D1 determines the voltage at R6, enter the inputs of overload switching – Conclusions 4 and 5 D1. The voltage on the R6 increases with what greater than the load current (and actual current consumption from the source).

A pair of output transistors connected in parallel circuits D1 (emitter terminals 14 and 11, collectors – the outputs of 12 and 13). Loaded with collectors of output transistors a resistor R10. With this resistor pulses are fed to the non-inverting switch on transistors VT1 and VT2. Transistor VT1 is the pre-inverter, and s as the output transistor VT2 uses a powerful field-effect transistor with a small key resistance of the open channel. Due to the low impedance of the open channel, in spite of considerable current, power dissipated in it is small, and almost no heat sink required. Exclusively “to ensure” it is installed on the radiator plate output transistor Vertical TV type 3 USTST (plate size of approximately 25h35mm).

Pumping voltage is on the inductor L1. Diode VD2 rectifies the pulses of self-inductance and across the capacitor C11, there is a constant voltage.

In order to stabilize the output voltage using a comparator inputs are, pins 1 and 2 D1. On pin 2 through a divider R1-R2 is fed from the internal reference voltage regulator circuit (output of the stabilizer, – output 16). At the output a voltage is applied from the output of the power supply, low divider R3-R4-R5. The value of the output voltage depends on the ratio of the divider apart, and set trimmer R4 (in fact, ranging from 15 to 22 volts). It is desirable that the resistor R4 was multi-turn – so its installation is more accurate and more stable.

Below Circuit Laptop Power Supply for Car

Laptop Power Supply for Car


The circuit relatively simple circuit adapter (DC-DC converter), which increases the voltage-board vehicle network to 19V, needed to supply the laptop. And maintain this voltage stable. The adapter is based on chip LM3524, which is a high-frequency switching DC-DC converter with pumped inductance and output current up to 200mA, the output current which, in this scheme, will increased to 3.5-4A using a powerful transistor switch (on transistors VT1 and VT2).

  • The coil L1 is wound on a ferrite magnetic core ring outer diameter of 28mm. A total of 30 turns
  • Diode VD2 (Schottky diode) should allow a direct constant current of at least 5A.
  • BU278 transistor can be replaced by any other similar transistor, for example, BUZ21L
  • LM3524 chip is desirable to select a DlP-body (easier to solder). You can replace a chip SG3524, but other production.
  • Resistor R6 – wire, with a capacity not less than 2W.
  • All capacitors must be rated for a voltage below 25V.
  • When connected to a vehicle on-board network, you must strictly observe polarity. Otherwise, the inverter fails. Optimally – Connect directly to battery terminals. In this case it will be a minimum of interference. Converter housing must be shielded.

LM317 Calculator

This calculator helps you set the output voltage of LM317 regulator IC by simply replacing the value of both R1 and R2. The value of R1 usually varies from 100 t0 1000 ohms while R2 is of any value and preferably a trimmer type or potentiometer. The output voltaged desired can be calculated using this formula.

Vout = Vref*(1+(R2/R1))+ (Iadj*R2)where Vref = 1.25V and Iadj = 100uA.

The first calculator allows you to set the value of both R1 and R2 to determine the output voltage regulated by LM317. The next calculator allows you to set your desired output voltage and value of R1 to determine the value of R2.

LM217 Calculator


find here

Super Boost USB Charger Circuit

This design is inspired by the Minty Boost but it fixes some of the issues that I had with it. The Minty Boost is limited to 600mA due to the LT1302 chip. The Super Boost uses the LM2700 which can push up to 3.6A. This will enable i-devices to draw up to there maximum of 1A which will enable a faster recharge. 

Super Boost USB Charger Circuit

Electronic Fuse for DC Short Circuit Protection

This is an electronic fuse that protects the load against short circuit. Relays must be chosen with a voltage value equals to the input voltage. Don’t omit using the 100uF capacitor with appropriate voltage value with respect to the input voltage. If you can’t provide, you can use C106 instead of BRX46.

Electronic Fuse for DC Short Circuit Protection

You can adjust the current with using 10K potentiometer. If you will use the fuse with very high currents, lower the 0R6 5W resistor value (ex. 0R47, 0R33, 0R22 or 0R1). Watt value of the resistor should be increased also

Timer Garage Door Circuit

Because I’m old school, I wanted to build a Garage Door Closing circuit without relying on integrated configurations (555 timer etc) to keep it simplistic. The circuit closes the garage door after two minutes with C3 and four minutes with the addition of C2. The timer relay is surprisingly accurate (+/- five seconds). Another feature is to ensure that the garage door actually did close, such as if it’s stopped mid-operation by the user.

Timer perfboard


S3 (magnetic N.C.) is located at the garage door and activates the circuit when the garage door opens.

RL1 is the reset timer. It’s maintained in the “on” position for two minutes by C3 while the trigger capacitor, C4, is charged. RL2 is the conduit, directing C4 to either RL3 or R1 to ground when off. Purpose of R1 is to prevent arching across contacts and a fast discharge. RL3’s contacts are connected to the Garage Door’s Momentary Switch and is sustained “on”  for a half second by C5.

When C3 discharges to the cutoff voltage of RL1, it turns off and resets. C4 charges C5, which turns on RL3 and initiates the garage door. Because C4 does not have the time to fully discharge, it should be at least three times the value of C5. If it does not close, RL1 in countdown mode will reset and open the door. When it resets again, the door will close.

Turning off the circuit, C1 maintains RL1 “on” slightly longer to ensure that RL2 is set to discharge C4 to R1. If this is not done and C4 is not discharged, the garage door will not open until it discharges naturally and falls below the trigger voltage for RL3.  The circuit would be useless for several days.

Timer Garage Door Circuit


-Time delay of RL1 after reset drops 15 seconds because of the short charge time.

-To boost RL3 to a one-second delay, increase C5 to 1000uF.

-D2, D3, and D4 isolate the crucial sections of the circuit.

-Relays do not turn off at the same rate. I conducted a test by tripping the circuit on and off at a high rate and discovered the possibility of C4 turning on RL3. The addition of C1 solved this.

*Author: Roland Segers (

Pushbutton Relay Selector Circuit Diagrams

This circuit was designed for use in a hifi showroom, where a choice of speakers could be connected to a stereo amplifier for comparative purposes. It could be used for other similar applications where just one of an array of devices needs to be selected at any one time. A bank of mechanically interlocked DPDT pushbutton switches is the simplest way to perform this kind of selection but these switches aren’t readily available nowadays and are quite expensive. This simple circuit performs exactly the same job. It can be configured with any number of outputs between two and nine, simply by adding pushbutton switches and relay driver circuits to the currently unused outputs of IC2 (O5-O9).

Gate IC1a is connected as a relax-ation oscillator which runs at about 20kHz. Pulses from the oscillator are fed to IC1b, where they are gated with a control signal from IC1c. The result is inverted by IC1d and fed into the clock input (CP0) of IC2. Initially, we assume that the reset switch (S1) has been pressed, which forces a logic high at the O0 output (pin 3) of IC2 and logic lows at all other outputs (O1-O9). As the relay driver transistors (Q1-Q4) are switched by these outputs, none of the relays will be energised after a reset and none of the load devices (speakers, etc) will be selected. Now consider what happens if you press one of the selector switches (S2-S5, etc). For example, pressing S5 connects the O4 output (pin 10) of IC2 to the input (pin 9) of IC1c, pulling it low.

Circuit diagram:

Pushbutton Relay Selector Circuit Diagram

Pushbutton Relay Selector Circuit Diagram

This causes the output (pin 10) to go high, which in turn pulls the input of IC1b (pin 5) high and allows clock pulses to pass through to decade counter IC2. The 4017B counts up until a high level appears at its O4 output. This high signal is fed via S5 to pin 9 of NAND gate IC1c, which causes its output (pin 10) to go low. This low signal also appears on pin 5 of IC1b, which is then inhibited from passing further clock pulses on its other input (pin 6) through to its output (pin 4), thus halting the counter. So, the counter runs just long enough to make the output connected to the switch that is pressed go high. This sequence repeats regardless of which selector switch you press, so the circuit functions as an electronic interlock system.

Each relay driver circuit is a 2N7000 FET switch with its gate driven from one output of IC2 via a 100W resistor. The relay coil is connected from the drain to the +12V supply rail, with a reverse diode spike suppressor across each coil. If you want visual indication of the selected output, an optional indicator LED and series resistor can be connected across each relay coil, as shown. For selecting pairs of stereo speakers, we’d suggest the use of relays like the Jaycar SY-4052. These operate from 12V and have DPDT contacts rated for 5A. Note that although four selector switches are shown in the circuit, only two relay drivers are shown because of limited space. For a 4-way selector, identical relay drivers would be driven from the O2 and O3 outputs of IC2.

Author: Jim Rowe - Copyright: Silicon Chip Electronics


Stereo 80Watt Audio Amplifier TDA7294

The described circuit uses two TDA7294 for use in stereo (2 x 80 watts) and bridge mode (1x 180 watts), configure this setting only four drivers.

Stereo 80Watt Audio Amplifier TDA7294

To facilitate the installation of each fuel. The performance is a kind of symmetry with a simple bridge rectifier 6A, and two large electrolytic capacitors, which 10000µF 22000µF/50v. This power supply for two modules. The processor is recommended 22-0-22 to 28-0-28 / 5 A, depending on the quality of the transformer is at least 6 amps is recommended.

PCB design Stereo 80Watt Audio Amplifier TDA7294


PCB layout Stereo 80Watt Audio Amplifier TDA7294

The TDA7294 is a monolithic integrated circuit in MULTIWATT15 package for use as audio class AB amplifier in Hi-Fi field applications (stereo, powered speakers, car, high-end TV) is provided. Many thanks to the wide range of voltage and current capacity he is able to offer the highest property taxes in both 4O and 8O, to offer even in the presence of poor supply regulation, with the rejection of high-voltage power supply. The built-in mute with delay sounds easier to avoid the remote mode off.

Amplifier Circuit Diagram Class-A Headphone

400mW RMS into 32 Ohm load, Single-rail Supply - Optional Tilt Control

This design is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.

Tilt control:

The mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble lift and bass cut.

Circuit diagram:

Class-A Headphone Amplifier Circuit

Class-A Headphone Amplifier Circuit Diagram


P1 = 22K Dual gang Log Potentiometer (ready for Stereo)

R1 = 15K 1/4W Resistor

R2 = 220K 1/4W Resistor

R3 = 100K 1/2W Trimmer Cermet

R4 = 33K 1/4W Resistor

R5 = 68K 1/4W Resistor

R6 = 50K 1/2W Trimmer Cermet

R7 = 10K 1/4W Resistor

R8 = 47K 1/4W Resistors

R9 = 47K 1/4W Resistors

R10 = 2R2 1/4W Resistors

R11 = 2R2 1/4W Resistors

R12 = 4K7 1/4W Resistor

R13 = 4R7 1/2W Resistor

R14 = 1K2 1/4W Resistor

R15 = 330K 1/4W Resistors (Optional)

R16 = 680K 1/4W Resistor (Optional)

R17 = 220K 1/4W Resistors (Optional)

R18 = 330K 1/4W Resistors (Optional)

R19 = 220K 1/4W Resistors (Optional)

R20 = 22K 1/4W Resistors (Optional)

R21 = 22K 1/4W Resistors (Optional)

C1 = 10µF 25V Electrolytic Capacitors

C2 = 10µF 25V Electrolytic Capacitors

C3 = 10µF 25V Electrolytic Capacitors

C4 = 10µF 25V Electrolytic Capacitors

C5 = 220µF 25V Electrolytic Capacitors

C6 = 100nF 63V Polyester Capacitors

C7 = 220µF 25V Electrolytic Capacitors

C8 = 2200µF 25V Electrolytic Capacitor

C9 = 1nF 63V Polyester Capacitors (Optional)

C10 = 470pF 63V Polystyrene or Ceramic Capacitor (Optional)

C13 = 15nF 63V Polyester Capacitor (Optional)

C11 = 1nF 63V Polyester Capacitors (Optional)

C12 = 1nF 63V Polyester Capacitors (Optional)

D1 = 5mm. or 3mm. LED

D2 = 1N4002 100V 1A Diodes

D3 = 1N4002 100V 1A Diodes

Q1 = BC550C 45V 100mA Low noise High gain NPN Transistors

Q2 = BC550C 45V 100mA Low noise High gain NPN Transistors

Q3 = BC560C 45V 100mA Low noise High gain PNP Transistor

Q4 = BD136 45V 1.5A PNP Transistor

Q5 = BD135 45V 1.5A NPN Transistor

IC1 = 7815 15V 1A Positive voltage regulator IC

T1 = 220V Primary, 15+15V Secondary-5VA Mains transformer

SW1 = 4 poles 3 ways rotary Switch (ready for Stereo)

SW2 = SPST slide or toggle Switch

J1 = RCA audio input socket

J2 = 6mm. or 3mm. Stereo Jack socket

PL1 = Male Mains plug


  • Q4, Q5 and IC1 must be fitted with a small U-shaped heatsink.

  • For a Stereo version of this circuit, all parts must be doubled except P1, IC1, R14, D1, D2, D3, C8, T1, SW1, SW2, J2 and PL1.

  • If the Tilt Control is not needed, omit SW1, all resistors from R15 onwards and all capacitors from C9 onwards. Connect the rightmost terminal of R1 to the Base of Q1.

  • Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to zero resistance and Trimmer R3 to about the middle of its travel.

  • Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.

  • Connect a Multimeter, set to measure about 10Vdc fsd, across the positive end of C5 and the negative ground.

  • Switch on the supply and rotate R3 in order to read about 7.7-7.8V on the Multimeter display.

  • Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 200mA fsd, in series to the positive supply of the amplifier.

  • Switch on the supply and rotate R6 slowly until a reading of about 100mA is displayed.

  • Check again the voltage at the positive end of C5 and readjust R3 if necessary.

  • Wait about 15 minutes, watch if the current is varying and readjust if necessary.

  • Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.


Technical data:

Output power (1KHz sinewave):

  • 32 Ohm: 427mW RMS

  • 64 Ohm: 262mW RMS

  • 100 Ohm: 176mW RMS

  • 300 Ohm: 64mW RMS

  • 600 Ohm: 35mW RMS

  • 2000 Ohm: 10mW RMS



  • 140mV input for 1V RMS output into 32 Ohm load (31mW)

  • 500mV input for 3.5V RMS output into 32 Ohm load (380mW)

  • Total harmonic distortion into 32 Ohm load @ 1KHz:

  • 1V RMS 0.005% 3V RMS 0.015% 3.65V RMS (onset of clipping) 0.018%

  • Total harmonic distortion into 32 Ohm load @ 10KHz:

  • 1V RMS 0.02% 3V RMS 0.055% 3.65V RMS (onset of clipping) 0.1%

  • Unconditionally stable on capacitive loads

Inverter Circuit Diagram 9V to 13.5kV

This high voltage source is formed by an inverter, around the transistor, which provides pulses of 150V to the inverter formed by the thyristor and capacitor in series with the transformer 2. This pulse output of 4.5kV to be multiplied with the network so as to achieve the output voltage of 13.5kV.  Neon lamps (marked LN) form the thyristor triggering pulses.

The transformer T1 has a ratio 3000:500 O of the type used in audio output transistor. T2 is a transformer flash lamp trigger a secondary 6kV. This inverter circuit requires a 9VDC power supply with current 0.01A

9V to 13.5kV Inverter Circuit


Apply this equipment on the human body can cause serious physical injury to death. Don’t use in humans.

50W-70W Power Amplifier with 2N3055 & MJ2955

This good detail both circuit diagram ,PCB,part assembly,layout and show case in completed set that you can make with this information for 50 Watts Power Amplifier.

50W-70W Power Amplifier with 2N3055 & MJ2955

50W-70W Power Amplifier with 2N3055 & MJ2955


50W-70W Power Amplifier with 2N3055 & MJ2955


50W-70W Power Amplifier with 2N3055 & MJ2955


50W-70W Power Amplifier with 2N3055 & MJ2955


50W-70W Power Amplifier with 2N3055 & MJ2955

Could you read specification thus as below.

  • Output Power 50 watts into 8O 70 watts into 4O

  • Music Power 77 watts into 8O ;105 watts into 4O

  • Frequency response -1dB at 14Hz and 70kHz (at 1W- see Fig.1)

  • Input sensitivity 0.875V for 50O into 8O

  • Harmonic distortion <.05% from 20Hz to 20kHz; typically <.003%

  • Signal-to-Noise Ratio -114dB unweighted (22Hz to 22kHz); -119dB A-weighted, both with respect to 50W into 8O

  • Damping factor >140dB at 100Hz & 1kHz, with respect to 8O and without PTC thermistor

  • Protection fuses plus “Polyswitch” PTC thermistor

3V electronic stun gun circuit

This circuit above is a cheap version stun gun circuit that is powered by two AA baterry. The output of this electronic project is about 350V dc. The heart of the circuit is the oscillator that is composed of Windings and transistor.

3V electronic stun gun circuit

3V electronic stun gun circuit

Part List:

  1. Transistor - Tip41 or similar
  2. Resistor - 100-ohms 1W
  3. Capacitor-100nF
  4. C-1.2uF 1000V or any cap with 1000V rating
  5. D-1N4007 diode or similar


3V electronic stun gun circuit

Primary and Feedback winding

3V electronic stun gun circuit

TIP41 pins

Primary winding P is composed of 16 turns of #24 AWG wire, feedback F is composed of 8 turns of #24 AWG wire, and secondary winding S is composed of 270 turns of #30 AWG magnetic wire. P1 is connected to the collector of transistor, F2 to the 100-ohms resistor at transistor base. F1 and P2 to the battery. The output of Sec winding is rectified by Diode Bridge. The output capacitor is an electrolytic type that is rated 400V above. Capacitance of the output capacitor depends on what available on hand, but always keep in mind that the higher the value the better. this simple electronic project is dangerous when accidentally touched, thus avoid holding the output and discharge the capacitor before and after using.

One of the uses of this circuit is the camera flasher circuit.

24V from 12V regulator circuit diagram

The magnitude of this quiescent current is not closely controlled and hence the total output voltage becomes somewhat unpredictable. Low divider resistor values help, but there are likely to be complications of heat dissipation and inefficiency.

Increase Regulator Voltage Output


The circuit presented here avoids the problem by using the transistor T1 to generate a low impedance at the regulator common terminal by emitter-follow action, while transferring the voltage divider from a relatively high-resistance divider network. The value of R3 is not critical but must be low enough to accept the highest quiescent current without causing T1 to turn-off.

Tuesday, January 1, 2013

About us

This blog provides information for automotive lovers. or electronic gadgets. as discussed here a lot of information about it all. if you have suggestions or criticism you can use the contact us form that we have provided. hopefully this 1stmanual blogs can be useful and make your best references.



Dear visiotr if you require any more information or have any questions about our privacy policy, please feel free to contact us. at, the privacy of our visitors is of extreme importance to us. This privacy policy document outlines the types of personal information is received and collected by and how it is used.

Log Files
Like many other Web sites, makes use of log files. The information inside the log files includes internet protocol ( IP ) addresses, type of browser, Internet Service Provider ( ISP ), date/time stamp, referring/exit pages, and number of clicks to analyze trends, administer the site, track user’s movement around the site, and gather demographic information. IP addresses, and other such information are not linked to any information that is personally identifiable.

Cookies and Web Beacons does use cookies to store information about visitors preferences, record user-specific information on which pages the user access or visit, customize Web page content based on visitors browser type or other information that the visitor sends via their browser.

DoubleClick DART Cookie
.:: Google, as a third party vendor, uses cookies to serve ads on
.:: Google's use of the DART cookie enables it to serve ads to users based on their visit to and other sites on the Internet.
.:: Users may opt out of the use of the DART cookie by visiting the Google ad and content network privacy policy at the following URL -

Some of our advertising partners may use cookies and web beacons on our site. Our advertising partners include ....
Google Adsense

These third-party ad servers or ad networks use technology to the advertisements and links that appear on send directly to your browsers. They automatically receive your IP address when this occurs. Other technologies ( such as cookies, JavaScript, or Web Beacons ) may also be used by the third-party ad networks to measure the effectiveness of their advertisements and / or to personalize the advertising content that you see. has no access to or control over these cookies that are used by third-party advertisers.

You should consult the respective privacy policies of these third-party ad servers for more detailed information on their practices as well as for instructions about how to opt-out of certain practices.'s privacy policy does not apply to, and we cannot control the activities of, such other advertisers or web sites.

If you wish to disable cookies, you may do so through your individual browser options. More detailed information about cookie management with specific web browsers can be found at the browsers' respective websites.