Saturday, February 26, 2011
3-Input Mic Preamplifier Circuit Using Op-Amp LM348
This is a 3-input mic preamplifier circuit using IC LM348. The LM348 is a high gain, internally compensated quad operational amplifier with a class AB output stage. The IC has very low input supply current and operates from a dual power supply.
Out of the four op-amps inside the IC LM348, IC1a, IC1b and IC1c are wired as non inverting amplifiers and they serve as the input amplifiers for the corresponding mic channels. The output of these three amplifiers are tied together and connected to the inverting input of the IC1a which is wired as an inverting amplifier. IC1a mixes the signals from each channel and also works as the output stage.
LM1036 Stereo Tone Control Circuit
Here is a LM1036 stereo tone control circuit which build based on IC LM1036. This circuit will controll bass/treble level tone, volume and balance between right channel and left channel (input 1 and 2 ). You may use this circuit for stereo applications such as car radio, TV and audio systems, mp3 player, dvd player, ipod and more. An additional control input allows loudness compensation to be simply effected. The circuit should be works with supply voltage 9V to 15V DC.
Each tone response is defined by a single capacitor chosen to give the desired characteristic. By changing the values of capacitor connected to tone controlling unit, you can control bass and treble levels. pin 3 and pin 18 of IC are for treble and pin 6 and pin 15 for bass.
Op-Amp UA739 Dynamic Microphones Preamplifier
This is a low noise preamplifier circuit for dynamic microphones. The circuit is based on the Op-Amp UA739. The uA739 is a dual audio operational amplifier with high gain and excellent stability. Out of the two opamps available in the IC, only one is used here.
The audio signals from the microphone are coupled to the non inverting input of IC1 through the capacitor C1 and resistor R1. C1 performs input DC decoupling. The R1, C2 network bypasses the unwanted high frequency signals from the microphone. A fraction of the output is fed back to the inverting input in order to prevent oscillations and ensure better stability. The input impedance of this circuit is around 50K.This amplifier can handle signal from 20Hz to 20 KHz, which makes it excellent for audio applications.
LA3600 5 Band Graphic Equalizer
LA3600 graphic equalizer circuit shown here. This circuit very suitable for applications like portable stereo, radio sets, home theater systems, car audio systems etc.
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| LA3600 5 Band Graphic Equalizer Circuit |
In the circuit capacitors C1, C3, C5, C7 and C9 are used to fix the resonance frequency of the corresponding bands. Capacitors C2, C4, C6, C8, C10 and C15 are the input capacitors and increasing the value of these capacitors will increase the low frequency response. Capacitor C13 is a decoupling capacitor and C14 is a power supply filter circuit. C12 is the output capacitor and resistor R6 limits the supply current. Gain of each band can be adjusted by using the corresponding potentiometers R1 to R5
Op-Amp 741 Guitar Preamplifier Circuit
This preamplifier circuit suitable for high impedance type electric guitar.The circuit is based on a UA 741 op-amp. The UA741 is wired as a non-inverting amplifier.The POT R1 can be used as a volume controller.The POT R6 can be used as tone controller.The switch S1 is used to produce “brilliant” or “soft” tonal effects
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| Op-Amp 741 Guitar Preamplifier Circuit |
Thermistor 12VDC Fan controller Circuit
This is an automatic 12VDC fan circuit for audio amplifiers. The circuit automatically switch ON the cooler fan whenever the temperature of the heat sink exceeds a preset level. This circuit will save a lot of energy because the cooler fan will be OFF when the amplifier is running on low volume. At low volume less heat will be dissipated and it will not trigger the cooler fan ON.
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| Thermistor 12VDC Fan controller Circuit |
The temperature is sensed using an NTC thermistor R2. Junction of thermistor r2 and resistor R1 is connected to the inverting input (pin3) of IC1 which is wired as a comparator. The non-inverting input (pin2) is given with a reference voltage using the preset R3. As temperature increases the resistance of NTC thermistor will drop and so do the voltage across it. When the voltage at the inverting input becomes less than that of the reference voltage (set for a particular threshold temperature) the output of the comparator goes high and switches the transistor Q1 ON. This will activate the relay and the cooler fan will be switched ON. When the temperature decreases the reverse happens. LED D2 will glow when the fan is ON. Diode D1 is a freewheeling diode
3 Band Tone Control Circuit Using Op-Amp LF351
Here is the circuit of 3 band tone control using a single op-amp IC and few components. The IC used here is LF 351 which is a wide bandwidth single JFET operational amplifier.
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| Op-Amp 3 band tone control circuit |
The high input impedance of the IC makes this circuit compatible with most of the audio signal sources. The op-amp is wired as an inverting amplifier. The input signal is fed to the inverting input of the opamp via the filter network. The filter network can produce a +/- 20 dB enhancement or cut on the three frequency bands 50Hz,1KHz and 10KHz.POTs R1, R2 and R3 can be used for adjusting the gain of the different bands
IRF530 Fet Flasher Circuit
This is a simple fet flasher circuit that can be used for flashing 12V lamps especially that is used on automobiles.The flasher circuit is based on transistor BC557 and MOSFET IRF530 where the Q2 provides the necessary drive for the lamp.Any number of bulbs can be flashed using this circuit provided that the total load must not exceed 42 Watts. Circuit of this kind are particularly suited for road, traffic and yard alerts and in all cases where mains supply is not available but a powerful flashing light is yet necessary
Flashing frequency can be varied within a limited range by changing C1 value.
List Componet
R1 : 6K8 R2 : 220K R3 : 22K C1 : 100µF/25V C2 : 10µF/25V D1 : 1N4002 Q1 : BC557 Q2 : IRF530 LP1: 12V/21W Car Filament Bulb SW1: SPST Switch (3 Amp minimum)
Tuesday, February 22, 2011
LED Pulser Circuit Using Op-Amp LM358
This circuit operates a LED in pulsing mode, LED goes from off state, lights up gradually, then dims gradually. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Transistor Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds.
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| LED Pulser Circuit Using Op-Amp LM358 |
- The most satisfying results are obtained adopting for R4 a value ranging from 220K to 4M7. Adopting for R4 a value below 220K, the pulsing effect will be indistinguishable from a normal blinking effect.
- Voltage supply range can be 4 to 6V: 4.5V is the best compromise.
List Component of LED pulser circuit
R1,R2 : 4K7
R3 : 22K
R4 : 2M2 1/4W (See Notes)
R5 : 10K
R6 : 47R
C1 : 1µF Polyester Capacitor
D1 : 5mm. Red LED
IC1 : LM358 Dual Op-amp
Q1 : BC337
STK465 - 30 watt Stereo Power Amplifier Circuit
Completed STK465 is an amplifier of acoustic frequencies that offers qualitative output, using minimal exterior elements. Substantially he is one of big completed force. When it functions with tendency 56V then the tendency will be ± 28V as for the ground. With this recommended tendency of catering, the attributed force is 30 WRMS in charge 8 Ohm.
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| STK465 - 30 watt Stereo Power Amplifier Circuit |
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| STK465 Power Amplifier kit |
The STK465 Amplifier circuit is stereo and has two channels of amplifier in a nutshell. It is a formal designing that develops positively all the particularities completing. The amplifier can be supplied from a line of double polarity. Still it can function under a wide region of tendencies (±10V as ±28V). The requirements of current depend from the force of expense and it can they begin from 120mA up to 1A. It is very important the catering to be sufficiently unharnessing, so that is avoided imports of annoying noises.
Buzzer Burglar Alarm Circuit For Refrigerator
This circuit, enclosed in a small box, is placed in the fridge near the lamp. With the door closed the interior of the fridge is in the dark, the LDR R2 has a high resistance about 1000K ohm thus clamping IC1 by holding pin 12 high. When a beam of light enters from the opening, or the fridge lamp lights, the photo resistor lowers its resistance, pin 12 goes low, IC1 starts counting and, after a preset delay, the piezo sounder beeps for 20 sec. then stops for the same lapse of time and the cycle repeats until the fridge door closes. D2 connected to pin 6 of IC1 makes the piezo sounder beeping 3 times per second.
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| Buzzer Burglar Alarm Circuit For Refrigerator |
- Delay time can be varied changing C1 and/or R3 values.
- Place the circuit near the lamp and take it away when defrosting, to avoid circuit damage due to excessive moisture Don't place it in the freezer.
R1 : 10K
R2 : LDR (any type)
R3,R4 : 100K
C1 : 10nF Polyester Capacitor
C2 : 100µF/25VD1
D2 : 1N4148
IC1 : 4060
Q1 : BC337
BZ1 : Piezo sounder (incorporating 3KHz oscillator)
SW1 : SPST slide Switch
LDR Relay Switch Circuit
This is a LDR switch or light activated relay circuit. This circuit will let you make a switch that will be activated by light falling on a sensor. It is a very useful device and can be used in automatism’s, security systems, counters, remote controls etc. It is very sensitive, fast acting and reliable. The circuit uses a Light Dependent Resistor (LDR) as a sensor and IC LM311 to amplify the signals from the LDR and transistor 2N2222 to drive the relay which does the switching.
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| LDR Relay Switch Circuit |
Normally the resistance of an LDR is very high, sometimes as high as 1000 Kohms, but when they are illuminated with light resistance drops dramatically. The relay on when LDR uncoverd and relay off when LDR covered. Adjust VR1 for light sensitive.LED will turn on at the same time with relay
Monday, February 21, 2011
Triac Light Dimmer Circuit
This is a simple 220V light dimmer circuit based triac can be used to adjust the brightness of mains lights about 350 watts. It also can be used to adjust the speed of AC motors. It uses a triac, diac and has a radio-frequency interference (RFI) noise suppression circuit built into it as well. Please note that this circuit cannot be used with fluorescent lights.
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| Triac Light Dimmer circuit |
R1 : 50K Pot
R2 : 15K 1/2W Resistor
C1, C2 : 0.068 250V Capacitor
L1 : Lamp To Be Controlled (up to 350 watts)
L2 : Neon Lamp
TR1 : 40502 TRIAC
Note:
- This circuit is for 117VAC only. 220 or 240 V will burn up the circuit. L1 can be a maximum of 350 watts.
- The circuit must be installed and used in a case.
Heat sink is necessary for 40502 TRIAC
Simple 220V AC Blinking LED Using Diac
needed a blingking led for a certain signaling. Voltage was 220V. So I decided to make a simple circuit, consisted of a LED diode, two capacitors, two resistors, a diac and a diode.
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| Simple 220V AC Blinking LED Using Diac |
Activity of the circuit is extraordinarily simple. The capacitor charges by the diode and the resistor. When the voltage on the capacitor achieves 30V the diac "releases" the electrical tension and the capacitor empties thorough the diac, LED blinks. Time base is dependent from the capacitor and the resistor, which is in series with diode 1N4007. Capacitor must be at least for 40V.
Sunday, February 20, 2011
2 Way Active Crossover Circuit
Here is the schematic of a 2 way active cross- over network circuit that finds a lot of application in audio amplifier systems. The circuit use a constant voltage method, means that the output of high and low frequency is summed up, and then fed back to be compared with the input to make sure this sum is equal to the input signal. This method ensure that the total response is flat, if we summed back the separated high and low frequency output.
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| 2 Way Active Crossover Circuit |
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| LM833 Pin-Out |
You have to use 1% tolerance for the resistors to give a precise response. According to the formula, the capacitor C should be 6.6nF to give 1kHz crossover frequency, but a 6.8nF can be used because it waidely available, and the crossover frequency will be shifted to about 975Hz.
NE555 12VDC Fluorescent Lamp Driver Circuit
This is a circuit of 12VDC fluorescent lamp Driver for those who look for Fluorescent lamp driver using ordinary transformers. The transformer used is a step-down transformers from 120 to 6V in reverse, so that with primary voltage 12V could produce 350V for output. This voltage is used to turn on the fluorescent lamp without heating the filament.
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| NE555 12VDC Fluorescent Lamp Driver Circuit |
The IC1 TLC 555 is wired as an astable multivibrator for producing the necessary oscillations.The MOSFET Q1 is used to amplify the oscillations produced by the IC1.The out put of MOSFET is connected to the primary of the step up transformer to produce a ~350 V AC for driving the florescent lamp.
Note:
- Take note that heat sink should be used on Q1, and be careful of the electric shock from the output voltage!
- For T1, use a 10W ,230V to10V step down transformer in the inverted configuration.That is 10V winding must be connected to the MOSFET side and 240V winding must be connected to florescent lamp side.
C1 : 100uF/25V
C2,C3 : 0.01/25V Ceramic Capacitor
C4 : 0.01/1kV Ceramic Capacitor
R1 : 1K
R2 : 2.7K
Q1 : IRF510 MOSFET
U1 : NE555 Timer IC
T1 : see note
LAMP : 4W Fluorescent Lamp
12V to 220V Inverter Using 2n3055 Transistor
Here is a simple 12 V to 220V inverter for using a small aplications in the absence of mains supply. It uses eight transistors and a few resistors and capacitors. Transistors T1 and T2 form an astable multivibrator that produces 50Hz signal. The complementary outputs from the collectors of transistors T1 and T2 are fed to pnp Darlington driver stages formed by transistor pairs T3-T5 and T4-T6. The outputs from the drivers are fed to transistors 2N3055 (T7 and T8) connected for push-pull operation.
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| Circuit Of 12V to 220V Inverter Using 2n3055 Transistor |
A 230V AC primary to 12VCT/4.5A secondary transformer is used. The centre-tapped terminal of the secondary of the transformer is connected to the battery (12V, 7Ah), while the other two terminals of the secondary are connected to the collectors of power transistors T7 and T8, respectively.
When you power the circuit using switch S1, transformer X1 produces 230V AC at its primary terminal. This voltage can be used to heat your soldering iron. Assemble the circuit on a general purpose PCB and house in a suitable cabinet. Connect the battery and transformer with suitable current-carrying wires. On the front panel of the box, fit power switch S1 and a 3-pin socket for connecting the soldering iron.
Note:
Use suitable heat-sinks for transistors T5 through T8.
On-Off Touch Switch Using IC CD4011 Circuit
This is a circuit of electrnic on-off Touch switch controller using IC CD 4011 that is connected as a FLIP-FLOP. He is simple in the manufacture and the materials that use they exist everywhere. This based in the known CD 4011, which drives a relay of which the contacts play the role of switch. The metal surfaces can have what form we want, but it should they are clean and near in the circuit. In order to it changes situation it suffices touch soft somebody from the two plates.
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| On-Off Touch Switch Using IC CD4011 Circuit |
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| CD4011 (IC FLIP-FLOP) Pinnning |
This high sensitivity of the circuit makes the touch switch operation possible. The two gates are held at logic state «1» continuously by means of the two resistors R1 and R3 that connect them to the positive supply rail. These resistors have a very large resistance of 10 Mohm. If we now touch a set of contacts the skin resistance closes the circuit between the corresponding gate and the negative supply rail. The skin resistance for small areas of the skin is normally much lower than 10 Mohm and the gate is effectively brought to logic condition «0» which makes the FLIP-FLOP change state. For any given state of the FLIP-FLOP touching the corresponding set of contacts will make the circuit to reverse its state of balance and in effect toggle the switch. As a switch is used a relay driven by a transistor which is driven from the out put of the FLIP-FLOP.
List Component Of On-Off Touch Switch Circuit
R1 : 10MOhm 1/4 W
R2 : 10MOhm 1/4 W
R3 : 1KOhm 1/4 W
D1 : Led red
D2 : 1N4148 diode
TR1 : BC558 PNP Transistor – BC327
IC1 : CD4011 CMOS IC
RL1 : 12V relay rated at 250 V / 2A
Thursday, February 17, 2011
TDA 2616 - 1 2W Stereo Hi-Fi Amplifier Circuit
This is a circuit diagram of 2X12 W Hi-Fi Amplifier based on TDA 2616 IC which is the core part of this circuit. The TDA2616 is a stereo power amplifier IC. This amplifier IC finds applications in mains fed amplifier circuits such as stereo radio, tape and television. It has gain balance for both of the channels and hi-fi according to standards such as IEC 268 and DIN 45500. This IC has special inbuilt circuit for the suppression of noise signals at the inputs, during switch-on and switch-off. This avoids click sounds during power on and power off.
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| TDA 2616 - 1 2W Stereo Hi-Fi Amplifier Circuit |
Simple and less number of components make this circuit suitable for portable power amplifier circuits. A well regulated and filtered +/- 12 V dual power supply is used in this circuit to provide at least 2 A continuous current. The circuit can deliver a maximum output of 12 W power on 8 Ohm speaker for each channel at +/- 12 V dual supplies. This Hi-fi amplifier circuit can complement your audio system with ceiling speakers for home theater.
DC Motor Speed Controller Using NE555 PWM Switching
The following project is a PWM fan control, It is very easy to be built and it can efficiently control all DC fans to rpm as low as 450 rpm (the lowest limit has to do with the fan type and manufacturer). It uses ONLY one 555 timer and a few other components, and it can be powered also directly from the PC power supply, from the 12 Volts line.
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| DC Motor Speed Controller Circuit Using NE555 PWM Switching |
The 555 will create a series of PWM pulses and will be driven directly to the gate of the MOSFET. The MOSFET is chosen to be big enough to carry enough loads, up to 9.2 amperes. You can choose a MOSFET according to your needs.
The MOSFET will generate enough power so that the motor will start revolving. The capacitor across the MOSFET is the solution to the'kicking sound'. The MOSFET will send to the motor pulses according to the pulses generated from the 555. If you remove the capacitor, you will definitely hear this annoying sound. The capacitor will smooth the voltage across the motor and therefore the power driven to it will be smooth, avoiding the torque kick
STK672-110 Full|Half Stepper Motor Controller
The STK672-110 chip has no microstepping mode and also has some less capabilities than the 080, yet it is very flexible and compact for full and half wave stepper motor applications.
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| STK672-110 Full|Half Stepper Motor Controller Circuit |
S1 controls the rotation direction of the motor. The reset circuit (R1-D1-C3) is as described by the manufacturer of the chip. You can use this input (Pin 6) for making resets other ways, like for example if you plan to control the chip with a microcontroller. In this case, you need to know that you must make a 10msec reset, every time that the chip is powered for the first time.
From the "MODE" input you control the type of stepper control. In this circuit, the chip connected for half-step. If you change the MODE input from +5 to GND, the circuit will work as a full step motor controller.
As for the coils of the motor, you need to connect the common wires of the coils (can be 1 or 2 on a unipolar motor) to the "C" connector, and the other 4 wires to the connectors "1" through "4". Usually, unipolar motors with 5 wires have the outputs in "1-2-C-3-4" row, and with 6 wires goes like "1-2-C-3-4-C" or "C-1-2-C-3-4" but this is can change! This is NOT always the same. You can go with trial and error or by measuring the coils of the motor to find the correct order. Do not forget the C4 capacitor!
About C4: In the Bill Of Materials underneath, this capacitor as 220uF 100V... Just playing safe. The chip can handle up to 50V, but this does not mean that cannot handle less. So, if your motor is like 3.3 volts or 5 volts, then a 100V capacitor is just too much. Get a 220uF 16V instead. Just do not be too close, for example, if your motor is powered with 12 Volts, go to 220uF 25 volts better. Electrolytic capacitors make a rather unpleasant noise when they explode.
For more details about STK672-110 stepper motor controller circuit please visit pcbheaven.com
LDR Light / Dark Activated Relay Switch
This is a simple Light / Dark Activated Relay circuit with the base of the LDR. The voltage divider has two resistors. The first is the 100K potentiometer plus the protective 1K resistor. the second resistor is the LDR.
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| LDR Light / Dark Activated Relay Circuit |
As light falls on the surface of the LDR, the LDR changes it's resistance. The more the light, the less the resistance of the LDR, the less the resistance, the less the voltage drop across it. The less the light, the more the resistance and thus the more the voltage drop across it.
As the voltage drop increases, so does the VB of the 2N2222 transistor and therefore the ICE increases accordingly, until the time that the current is enough to actuate the relay.
The amount of light needed to actuate the relay can be changed by changing the 100K potentiometer. Basically, any change to the potentiometer will have an effect to the voltage drop of the LDR, as they are both members of the voltage divider described above.
The 1N4001 diode is used to eliminate any back voltage when the relay is disarmed. It is very important to have this diode because without it, the transistor may be damaged.
2-Transistor Electronic Touch Switch
A simple electronic touch switch can be constructed using this circuit diagram . This electronic touch switch circuit is based on 2-transistors an can activate a relay. Putting a finger on the touch pads turns the top transistor ON and this transistor turns on the bottom transistor. When the finger is removed, the circuit consumes less than a microamp.
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| 2-Transistor Electronic Touch Switch circuit |
The touch sensor can be constructed using a small piece of a printed circuit board ( two small tracks with a 2 mm distance between each other ) . This circuit is powered using a 12 volts DC power supply , so the relay used for this project must be a 12 volts relay . This circuit is working very simple , when both plates of the sensor are touched the skin resistance will activate the circuit.
NE555 simples Touch Switch
The 555 can be used to create a Touch Switch. The only problem with this is the 555 consumes about 8mA, at all times when the supply is connected. This circuit is a simple touch plate controller which when touched on the touch plate operates the relay for a preset time then turns off automatically. This circuit has got applications in common equipments like touch operated doorbells, toys, buzzers etc. See below for an ON-OFF touch switch using a 555.
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| NE555 simples Touch Switch Circuit |
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| NE555 Pinout |
The trigger pin of NE 555 has high input impedance. This property is exploited in this circuit in such a way that human body induced voltage is used for triggering this IC. When this IC is triggered, its output goes to high for a time duration determined by resistor R1 and capacitor C1. The relay used here is driven by a transistor. This relay contact is utilized here to drive loads like bell, lights, motor etc.
Note: To setup the circuit connect to power supply and adjust R1 while keeping touching on the touch plate and stop at the point where relay activates.
Saturday, February 12, 2011
12VDC to 220VAC Inveter using IC 555
This 12VDC to 220VAC inverter circuit produces an AC output at line frequency and voltage. The 555 is configured as a low-frequency oscillator, tunable over the frequency range of 50 to 60 Hz by Frequency potentiometer R4.
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| Circuit of 12VDC to 220VAC 555 Inveter |
The 555 feeds its output (amplified by Q1 and Q2) to the input of transformer T1, a reverse-connected filament transformer with the necessary step-up turns ratio. Capacitor C4 and coil L1 filter the input to T1, assuring that it is effectively a sine wave. Adjust the value of T1 to your voltage.
12 VDC Fluorescent Lamp Inverter
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| 12 VDC 8 Watt Fluorescent Lamp Inverter Circuit |
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| Transformer details |
The circuit shown in the above has been Designed to drive an 8Wfluorescent lamp from a 12V source, using an Inexpensive inverter based on the ZTX652 transistor. The inverter will from operate from supplies in the range of 10V to 16.5V, attaining efficiencies up to 78% thus making it Suitable for use in on-charge systems Such as caravans / mobile homes / RVS as well as periodically charged systems Such as roadside lamps, camping lights or lights etc outhouse. Other features of the inverter are That it oscillates at an inaudible 20kHz and That it includes reverse polarity protection.
For more detail diodes.com
CD40110BE - 4 Digit Up/Down Counter
This is a simple up down counter circuit that can be used of a large number of applications. The circuit is based on the IC CD40110BE which is a CMOS decade up/down counter.
Common cathode seven segment display is connected to the 7-segment output of each IC.Display connected to the IC1 represents the lowest number and display connected to IC4 represents the largest number. Synchronous counting is achieved by connecting BORROW and CARRY pins of the preceding stage IC to the CLK DOWN and CLK UP of the next stage IC. For UP counting trigger pulse must be given to the pin7 of IC1 and for down counting trigger pulse must be given to the pin9 of IC1.The RESET pins of all IC are shorted and they have to be connected to ground during normal operation. Connecting the RESET pins to positive supply using the switch S1 resets the counter.
4-Channel Audio Mixer Using Op-Amp 741
Here is a simple 4 channel audio mixer that has proved useful. Using this mixer alleviates the need to unplug and plug the various audio sources from the recorder input.
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| Circuit of 4-Channel Audio Mixer Using Op-Amp 741 |
The 4 inputs are connected to a summing network consisting of R1 to R4, each input has its own level control ( VR1 to VR4 ). The output of the summing network is connected to the inverting input of the 741 op amp which is configured as a inverting amplifier with a voltage gain of exactly 1, the feedback resistor R5 in conjunction with R1 - R4 ensures this. As the inverting input of the op amp is a virtual earth, each individual mixer input is completely isolated from all the other inputs. Up to fifty or so inputs could be used here providing the sum of all the voltages present on the mixer inputs never exceeds the supply rail of the op amp ( within two volts of supply using this op amp ). The non inverting input of the 741 is biased to half supply by R6 and R7. All of the summed or mixed signals appear on the output of the op amp pin 6 and they will be 180 degrees out of phase with the input signal, for this application the phase inversion is of no consequence here.
The output of the mixer is also fed to D1, D2, and TR1 which is a simple peak indicator. D1, D2, C7 and C8 form a charge pump circuit which rectifies the AC signal present on pin 6 of the 741 to an average DC level, this in turn is used to illuminate the LED via TR1. I adjusted the preset pot so the LED just starts to glow for an input of 2 volts peak to peak
Wednesday, February 9, 2011
Low Cost Siren Using 3-Transistor
This is a low-cost siren circuit to add to our range of alarm modules. This circuit generates a tone that sounds very similar to a siren.
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| Low Cost Siren Using 3-Transistor Circuit |
A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit. Pressing on P1, C2 gradually discharges through R8: the circuit starts oscillating at a low frequency that increases slowly until a high steady tone is reached and kept indefinitely. When P1 is released, the output tone frequency decreases slowly as C2 is charged to the battery positive voltage through R6 and the Base-Emitter junction of Q2. When C2 is fully charged the circuit stops oscillating, reaching a stand-by status.
Notes:
- A good sized loudspeaker will ensure a better and powerful output tone.
- As stand-by current drawing is zero, SW1 can be omitted and B1 wired directly to the circuit.
R1,R3 : 1K C1,C2 : 22µF/25V
R2,R5 : 10K C3 : 10nF
R4 : 220R C4 : 47µF/25V
R6 : 220K Q1,Q2 : BC557
R7 : 22K Q3 : BC337
R8 : 100K
SW1 : SPST Toggle or Slide Main Switch (See Notes)
P1 : SPST Pushbutton Operating Switch
SPKR : 8 Ohm Loudspeaker
B1 : 12V Battery
220 Volts Flashing Lamps
This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing.
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| 220 Volts Flashing Lamps Circuit |
The schematic diagram 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.
List Component of 220 Volts Flashing Lamps circuit
R1 : 100K
R2,R5 : 1K
R3,R6 : 470R
R4 : 12K
C1 : 1000µF/25V
D1-D4 : 1N4007
D5 : P0102D
Q1 : BC327
Q2 : BC337
PL1 : Male Mains plug
SK1 : Female Mains socket
Warning! The device is connected to 220Vac 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.
2N3055|MJ2955 Class B Amplifier
This simple Class B Amplifier, straightforward but rugged circuit, though intended for any high quality audio application and, above all, to complete the recently started series of articles forming the Modular Preamplifier Control Center, is also well suited to make a very good Guitar or Bass amplifier.
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| 2N3055|MJ2955 Class B Amplifier Circuit |
Using a mains transformer with a secondary winding rated at the common value of 25 + 25V (or 24 + 24V) and 100/120VA power, two amplifiers can be driven at 45W and 69W output power into 8 and 4 Ohms respectively, with very low distortion (less than 0.01% @ 1kHz and 20W into 8 Ohms).
List Componet of 2N3055|MJ2955 Class B Amplifier circuit
R1 : 18K D1,D2,D3,D4 : 1N4148
R2 : 3K9 Q1,Q2 : BC560C
R3,R6 : 1K Q3,Q4 : BC556
R4 : 2K2 Q5 : BC546
R5 : 15K Q6 : BD139
R7 : 22K Q7 : BD140
R8 : 330R Q8 : MJ2955
R9,R10 : 10R Q9 : 2N3055
R11,R12 : 47R
R13 : 10R
C1 : 1µF/63V
C2 : 470pF
C3 : 47µF/25V
C4 : 15pF
C5 : 220nF
C6 : 100nF
Simple Adjustable Voltage Using 2-Transistor
A simple but less efficient method of controlling a DC voltage is to use a voltage divider and transistor emitter follower configuration.
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| Circuit of Simple Adjustable Voltage Using 2-Transistor |
The schematic diagram above illustrates using a 1K pot to set the base voltage of a medium power NPN transistor. The collector of the NPN feeds the base of a larger power PNP transistor the which supplies most of the current to the load. The output voltage will from be about 0.7 volts below the voltage of the wiper of the 1K pot so the output of cans be adjusted from 0 to the full supply voltage minus 0.7 volts. Using two transistors Provides a current gain of around 1000 or more so That only a couple milliamps of current is drawn from the voltage divider to supply a couple amps of current at the output. Note That this circuit is much less efficient Than the 555 timer dimmer circuit using a variabe duty cycle switching approach.
In the schematic diagram above, the 25 watt / 12 volt lamp draws about 2 amps at 12 volts and 1 amp at 3 volts so the power lost Pls That the lamp is dim is around (12-3 volts * 1 amp) = 9 watts. A Fairly large heat sink is required to Prevent the PNP power transistor from overheating. The power consumed by the lamp will from be only (3 volts * 1 amp) = 3 watts Gives us the which an efficiency factor of only 25% Pls the lamp is dimmed. The advantage of the circuit is simplicity, and Also That it does not generate any RF interference as a switching regulator does. The circuit cans be Used as a voltage regulator if the input voltage Remains constant, but it will from not compensate for changes at the input as the LM317 does.
Sunday, February 6, 2011
SMALL 6WATT POWER AMPLIFIER
The TA7222 is a power amplifier for consumer application.
It is designed for high power, low distortion and low noise.
It also contains various kind of protectors.
It is suitable for car – audio power amplifier with high performance.
Operating Supply Voltage Range Vcc = 9~18volt
High power is 6Watt
COMPONENTS LIST
Resistors:
P1=100kΩ
R1=27 kΩ
R2=220Ω
Capacitors:
C1=4,7μF/50V
C2=470μF/22V
C3=47μF/22V
C4=100nF
C5=47μF/22V
C5=470μF/22V
Semiconductors:
IC1= TA7222AP
Miscellaneous:
Heatsink for IC1
Wednesday, February 2, 2011
Simple Sine Wave Generator Based 2 Transistor
This Simple Sine Wave Generator circuit was designed to provide a valuable test equipment tool for sound reinforcement systems like guitar amplifiers and the like. Used in conjunction with an ac voltmeter or other ac measurement tools, it can be of considerable help in setting and controlling levels through any amplifying chain.
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| Simple Sine Wave Generator Using 2-Transistor BC550 Circuit |
The Simple Sine Wave Generator circuit is based on a simple, two-transistor oscillator circuit, featuring very high frequency and amplitude stability but avoiding thermistors, bulbs or any special amplitude-limiting device. Three different output frequencies, namely: 300Hz, 1KHz and 3KHz, are provided by switching SW1.
The sine wave output amplitude can be varied continuously (by means of P1) in two ranges: 0 - 77.5mV RMS (219.7mV peak-to-peak) and 0 - 0.775V RMS (2.191V peak-to-peak).A regulated supply is necessary to obtain a stable output waveform. D1 and D2 force IC1 to deliver 6.2V output instead of the nominal 5V.
List Componet Of Sine Wave Generator Circuit
P1 : 4K7 Potentiometer R1 : 12K R2 : 2K2 R3,R5,R7 : 1K Trimmers R4,R6 : 1K5 R8 : 1K R9 : 4K7 R10 : 3K3 R11 : 2K7 R12 : 300R R13 : 1K (Optional) R14 : 100K C1 : 22nF C2 : 3µ3 Polyester C3,C6 : 330nF C4 : 56nF C5 : 22µF/25V D1,D2 : 1N4148 D3 : LED Q1,Q2,Q3 : BC550C IC1 : 78L05 SW1 : 1 pole 3 ways Rotary or Slider Switch SW2 : 2 poles 3 ways Rotary or Slider Switch B1 : 9V PP3 Battery
Simple Signal Injector Using 2 Transistor
This is a signal injector circuit. Signal injector is important tool for troubleshooting your electronic circuits. As an example, this circuit can be used to test amplifier circuit. Here is the schematic diagram of the circuit:
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| Simple Signal Injector Using 2 Transistor Circuit |
This circuit also a lot of harmonics. By connecting the ground clip to the 0v rail and move through each stage, starting at the speaker, the fault in an amplifier can be found. At each preceding stage, the volume will increase. This circuit can inject FM sound sections in TV’s and the IF stages of radios.
When T1 conducts, its collector tension goes from high to low. Via C1, this is transmitted to the base of T2 making its collector tension drop from high to low as well. Via C2, this pulse blocks the base-current of T1, causing it to block up. As soon as the left side of C2 is charged enough by R3, T1 can conduct again and the cyclus is repeated.
12 Volt Transformerless Power Supply
This transformerless power supply circuit will of supply up to about 20mA at 12 volts. It uses capacitive reactance instead of resistance, and it does not generate very much heat.The circuit draws about 30mA AC. If you need more current, use a larger value capacitor, or put two in parallel, but be careful of what you are doing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2. The bridge rectifier cans be any of the small 'Round', 'In-line', or 'DIL' types; or Could you use four separate diodes.
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| 12 Volt Transformerless Power Supply Circuit |
This power supply can not be modified to Provide currents of greater (can not be up to several amps). The circuit was Designed to Provide a cheap compact power supply for Cmos logic circuits require only A Few That milliamps. The logic circuits were the resource persons then Used to control mains equipment (fans, lights, heaters etc.) through an optically isolated triac. If More Than 20mA is required it is possible to increase of C1 to 0.68uF or 1uF and thus obtain a current of up to about 40mA. But 'suppressor type' capacitors are Relatively big and more expensive Than Regular capacitors; and Increasing the current That means higher wattage resistors and zener diodes are required. If you try to Produce More Than about 40mA the circuit will from no longer be cheap and compact, and it simply makes more sense to use a transformer.
List componet of 12 Volt Transformerless Power Supply
C1 : 470nF/500V
C2 : 100µF/25V
R1 : anything from 1MΩ to 10MΩ
D1, D2, D3, D4 : 1N4007 or rectifier 230V AC
D5 : zenerdiode 12V or matching Uout desired
Simple Lamp Dimmer 220V using Triac
A very simple dimmer circuit with only the essentials. (In this circuit, the values are given for a BT138 at 220V AC, for 115V AC you may have to experiment with the values.)
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| Simple lamp Dimmer 220V Circuit |
- D1 = diac (silicon bidirectional trigger device) BR100, ER900 or similar
- Tr1 = triac BT138, TIC226...
- This circuit is potentially dangerous! this is nothing for beginners!
R1 can vary from one triac to another, put a 220KΩ trimmer in its place and adjust. After adjustment, measure the result and replace the trimmer with an ordinary resistor of the same value.
Circuit From: http://home.scarlet.be/
3-Digits Digital Volt Meter
This is simple 3-digits digital volt meter. The range is -99mV to +999mV. Two integrated circuits are used, the CA3161 and the CA3162.
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| 3-Digits Digital Volt Meter Circuit |
- The capacitor must be a low dielectric absorption type such as a polyester or polystyrene type.
- This capacitor should be placed as close as possible to the power and ground Pins of the CA3161E.
IC1 converts the analogous signal to a digital signal and also produces the multiplex signal to drive T1-T3. The BCD-code from IC1 then goes to IC2, a BCD to 7-segment decoder/driver. From there the signal goes to the displays.
The timing for the CA3162 is supplied by a 786Hz ring oscillator, and the input at pin 6 determines the sampling rate. A 5V input provides a high speed sampling rate (96Hz), and grounding or floating pin 6 provides a low speed (4Hz) sampling rate. When pin 6 is fixed at +1.2V (by placing a 12K resistor between pin 6 and the +5V supply) a 'hold' feature is available. While the CA3162E is in the hold mode, sampling continues at 4Hz but the display data are latched to the last reading prior to the application of the 1.2V. Removal of the 1.2V restores continuous display changes. Note, however, that the sampling rate remains at 4Hz.
The 'EEE' or '---' displays indicate that the range of the system has been exceeded in the positive or negative direction, respectively. Negative voltages to -99mV are displayed with the minus sign in the MSD. The BCD code is 1010 for a negative overrange (---) and 1011 for a positive overrange (EEE).
To callibrate the circuit, connect HIGH and LOW to mass and adjust P1 to read '000'. Then connect a tension from 0 to 1V to HI and LOW with LOW connected to mass. Adjust P2 to read the tension in mV.
The measuring range can be raised, using tension dividers. To use the decimal points, connect DP1, DP2 and/or DP3 to mass.
Circuit From: http://home.scarlet.be/
3 Digit Digital Frequency Counter
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| Digital Frequency Counter Circuit |
This circuit is a digital frequency counter. It covers region 1HZ until 1MHZ. The IC1 schmitt trigger that it regulates the signal of entry and him changes in reasonable level suitable for the IC2-3-4. With the tenth pulse in the entry of IC2/1, is produced a pulse '' carry '' in the IC3/5. The same moment the IC2 causes the depiction in the display 1, The IC3 causes the display 2. When in the entry of IC3 it reaches and the tenth pulse, the display 2 and the display 3, (with total depiction 100, having the display in right order). The exit '' carry'' off IC4/5, can be used in order to it turns on the decimal point (comma) the display 1, in order to it shows a situation over the limits of measurement.
The timed begins with the one of half double timer (IC5A). Switch S1 select the interruption the time in 1sec or in 1ms. At the duration of this interruption, second half the (IC5B), it produces a interruption of depiction 2 or 3sec., at the duration which counter cut off by the entry and the displays remain OFF. In the end of depiction, a pulse RESET, begins the interruption of time/depiction.
The critical point is round the Q1-IC1, which should be placed as long as it becomes more near in the jack of entry, to reject of parasitic signals of high frequency. For the regulation, we can use a frequency counter good precision (if you do not have you are lented) and a generator of signal. We put switch S1, in place [HZ], we apply in the entry a low frequency and we regulate the trimmer TR2, so that we take the right clue, which should suit with source frequency counter We repeat also the regulation for the department of KHZ, with a higher frequency. The supply of circuit becomes with a battery +9V, if it is used as portable or from suitable power supply if it is incorporated in some unit that exists already.
List Component
The timed begins with the one of half double timer (IC5A). Switch S1 select the interruption the time in 1sec or in 1ms. At the duration of this interruption, second half the (IC5B), it produces a interruption of depiction 2 or 3sec., at the duration which counter cut off by the entry and the displays remain OFF. In the end of depiction, a pulse RESET, begins the interruption of time/depiction.
The critical point is round the Q1-IC1, which should be placed as long as it becomes more near in the jack of entry, to reject of parasitic signals of high frequency. For the regulation, we can use a frequency counter good precision (if you do not have you are lented) and a generator of signal. We put switch S1, in place [HZ], we apply in the entry a low frequency and we regulate the trimmer TR2, so that we take the right clue, which should suit with source frequency counter We repeat also the regulation for the department of KHZ, with a higher frequency. The supply of circuit becomes with a battery +9V, if it is used as portable or from suitable power supply if it is incorporated in some unit that exists already.
List Component
R1 : 8.2Mohm IC2-3-4 : 4026
R2-9 : 100Koh IC5 : 556
R3 : 470Kohm IC6 : 4007
R4 : 470 ohm IC7 : 7805
R5-6-7 : 10Kohm DS1-3 : Display 7segment Comm. Cath.
R8 : 3.3Mohm TR1 : 1M ohm trimmer
C1-2 : 1uF 63V Mylar TR2 : 1Kohm trimmer
C3 : 47uF 16V Q1 : 2N930
C4 : 100nF 63V S1 : ON-OFF mini switch
C5 : 2.2uF 16V S2 : 1X2 mini switch
C6 : 10uF 16V
C7 : 10nF 63V Mylar
C8-10 : 1nF 63V Mylar
C9 : 1uF 16V
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