Simple 250W Inverter Circuit Diagram

This is a simple 250W Inverter Circuit Diagram. A 555 timer (IC1) generates a 120-Hz signal that is fed to a CD4013BE flip-flop (ICl-a), which divides the input frequency by two to generate a 60-Hz clocking frequency for the FET array (Ql through Q6). Transformer Tl is a 12-/24-V center-tapped 60-Hz transformer of suitable size. 

250W Inverter Circuit Diagram

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Flyback Converter Circuit Diagram

A low-current fly-back converter is used here to generate ±15 volts at 20 mA from a +5 volt regulated line. The reference generator in the SG1524 is unused with the input voltage providing the reference. Current limiting in a fly-back converter is difficult and is accomplished here by sensing current in the primary line and resetting a soft-start circuit.

Flyback Converter Circuit Diagram

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AVR Dongle Circuit

This circuit is intended to program AVR controllers such as the AT90S1200 via the parallel port. The circuit is extremely simple. IC1 provides buffering for the signals that travel from the parallel port to the microcontroller and vice versa. This is essentially everything that can be said about the circuit. The two boxheaders (K2 and K3) have the ‘standard’ ISP (in system programming) pinout for the AVR controllers. The manufacturer recommends these two pinouts in an attempt to create a kind of standard for the in-circuit programming of AVR-controllers. These connections can be found on many development boards for these controllers. The software carries out the actual programming task.

Circuit diagram :

AVR Dongle Circuit Diagram

It is therefore necessary to have a program (ATMEL AVR ISP), which is available as a free download from http://www.atmel.com. The construction of the circuit will have to made on standard prototype board, since we didn’t design a PCB for this circuit. This should not present any difficulties considering the small number of parts involved. We recommend that inexperienced builders first make a copy of the circuit and cross off each connection on the schematic once it has been made on the board. This makes it easy to check afterwards whether all connections have been made or not.

Author: P. G oossens - Copyright: Elektor Electronics

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Condenser Mic Audio Amplifier Circuit Diagram

The compact, low-cost condenser mic audio amplifier described here provides good-quality audio of 0.5 watts at 4.5 volts. It can be used as part of intercoms, walkie-talkies, low-power transmitters, and packet radio receivers. Transistors T1 and T2 form the mic preamplifier. Resistor R1 provides the necessary bias for the condenser mic while preset VR1 functions as gain control for varying its gain. In order to increase the audio power, the low-level audio output from the preamplifier stage is coupled via coupling capacitor C7 to the audio power amplifier built around BEL1895 IC.BEL1895 is a monolithic audio power amplifier IC designed specifically for sensitive AM radio applications that delivers 1 watt into 4 ohms at 6V power supply voltage. It exhibits low distortion and noise and operates over 3V-9V supply voltage, which makes it ideal for battery operation. A turn-on pop reduction circuit prevents thud when the power supply is switched on. Coupling capacitor C7 determines low-frequency response of the amplifier. Capacitor C9 acts as the ripple-rejection filter.

Circuit Diagram :

Condenser Mic Audio Amplifier Circuit Diagram

Capacitor C13 couples the output available at pin 1 to the loudspeaker. R15-C13 combination acts as the damping circuit for output oscillations. Capacitor C12 provides the boot strapping function. This circuit is suitable for low-power HAM radio transmitters to supply the necessary audio power for modulation. With simple modifications it can also be used in intercom circuits.

Author: D. Prabakaran - Copyright: Electronics For You Mag

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Safety Guard Circuit

Description

Protect your home appliances from voltage spikes with this simple time delay circuit. Whenever power to the appliances is switched on or resumes after mains failure, the oscillator starts oscillating and D5 blinks. This continues for three minutes. After that, Q14 output of IC CD4060 goes high to trigger the gate of the SCR through D4. At this moment, the voltage is available at the cathode of the SCR, which energizes the relay coil to activate the appliance and D6 glows. Switch SW1 is used for quick start without waiting for delay.

Circuit Diagram:

Parts:

• R1 = 1M
• R2 = 470R
• R3 = 820R
• R4 = 56K
• R5 = 470R
• R6 = 1K
• R7 = 10K
• C1 = 1kuF-25V
• C2 = 100nF-63V
• C3 = 0.02uF-63V
• C4 = 10uF-25V
• C5 = 10uF-25V
• D1 = 1N4007
• D2 = 1N4007
• D3 = 1N4007
• D4 = 1N4148
• D5 = Red LEDs
• D6 = Red LEDs
• RL1 = 12V Relay
• IC1 = AN7809
• IC2 = CD4060
• SW1 = Switch
• T1 = 24V-AC Centre Tapped Transformer

Circuit Operation:

 At the heart of the circuit is IC CD4060, which consists of two inverter gates for clock generation and a 14-bit binary ripple counter. Here the clock oscillations are governed by resistor R1 and capacitor C1. In this circuit, only two outputs of the IC (Q5 and Q14) have been used. Q5 is connected to an LED (D5) and Q14 is used to trigger the gate of the SCR through D4 as well as reset the counter. The anode of the SCR is connected to +9V and the cathode is connected to the relay coil. The other pin of the relay coil is connected to the negative supply, while its contacts are used for switching on the appliances.

Circuit Source -http://www.extremecircuits.net/2009/07/safety-guard.html

 Author: electronicsforu.com

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Build a Universal Active Filter Circuit Diagram

The Universal Active Filter Circuit Diagram as shown gives the bandpass operation the transfer function calculated from FBP(s) = where = 1 + s/Qo>0 + s2/w02. The cut-off frequency, 0, and the Q-factor are given by 0 = g/C and Q = gR/2 where g is the trans conductance at room temperature. Interchanging the capacitor C with the resistor R at the input of the circuit high-pass operation is obtained. A low-pass filter is obtained by applying two parallel connections ctf R and C as shown in Fig. 2. The low-pass operation may be much improved with the circuit as given in Fig. 3. Here the gain and Q may be set up separately with respect to the cut-off frequency according to the equations Q = 1/fB = 1 + R2/R!, A = Q2 and 0 = g ffi/C. 

 Build a Universal Active Filter Circuit Diagram

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1W BTL Audio Amplifier circuit and explanation

The TDA8581(T) from Philips Semiconductors is a 1-watt Bridge Tied Load (BTL) audio power amplifier capable of delivering 1 watt output power into an 8-Wload at THD (total harmonic distortion) of 10% and using a 5V power supply. The schematic shown here combines the functional diagram of the TDA8551 with its typical application circuit. The gain of the amplifier can be set by the digital volume control input. At the highest volume setting, the gain is 20 dB. Using the MODE pin the device can be switched to one of three modes: standby (MODE level between Vp and Vp–0.5 V), muted (MODE level between 1 V and Vp–1.4 V) or normal (MODE level less than 0.5 V). The TDA8551 is protected by an internal thermal shutdown protection mechanism. The total voltage loss for both MOS transistors in the complementary output stage is less than 1 V.

Circuit diagram:

1 Watt BTL Audio Amplifier Circuit Diagram

Using a 5-V supply and an 8-W loudspeaker, an output power of 1 watt can be delivered. The volume control has an attenuation range of between 0 dB and 80 dB in 64 steps set by the 3-state level at the UP/DOWN pin: floating: volume remains unchanged; negative pulses: decrease volume; positive pulses: increase volume Each pulse at he Up/DOWN pin causes a change in gain of 80/64 = 1.25 dB (typical value). When the supply voltage is first connected, the attenuator is set to 40 dB (low volume), so the gain of the total amplifier is then –20 dB. Some positive pulses have to be applied to the UP/DOWN pin to achieve listening volume. The graph shows the THD as a function of output power. The maximum quiescent current consumption of the amplifier is specified at 10 mA, to which should be added the current resulting from the output offset voltage divided by the load impedance.

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L200 Variable Power Supply Circuit

 L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt,2 amp rated secondary, the primary winding should equal the electricity supply. The 10k control is adjusts voltage output from about 3 to 15 volts, and the 47 ohm control is the current limit. This is 10mA minimum and 2 amp maximum. Reaching the current limit will reduce the output voltage to zero.

 

Power Supply Circuit.

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Residential Circuit Diagram Electrical Wiring Information

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Schematic Diagram.

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Electronic Circuit Diagram symbols 3

This is for beginners.Here there are more symbols

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Contactless telephone ringer circuit

The contact less telephone ringer circuit can produce a ring as well as a visual indication when a call comes.The main advantage is that since there is no direct contact between the phone line and the circuit there is no chance for a loading or disturbance in the telephone line.



When the telephone rings 60 Hz AC signal is generated which produces a proportional magnetic field around the telephone lines.These magnetic field will be picked up by the coil L1 due to electromagnetic induction.A proportional voltage is developed across L1 and it will bias transistor Q1 to ON.

This results in the conduction of transistors Q2,Q3 andQ4.The buzzer will ring and the LED will glow.The switch S1 acts as an ON/OFF switch.




Notes.

* For L1 make 50 close turns of 28 SWG enameled copper wire on any of the two telephone wires.Connect one end of the coil to base of Q1 and leave other end free.
* If the circuit not works by try by changing the end of the L1 connected to base of Q1.
* A 9V transistor radio battery can be used as the power source.
* Assemble the circuit on a good quality PCB or common board.
* Use of this type or any other devices other than the allowed telephones and devices with the telephone line may be a law violation in some nations.Check it properly before trying.

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FM Antenna Booster Circuit Diagram

This is a FM antenna booster circuit diagram.This helps you to get clear fm signals to your radio.The well important thing of this circuit is spending less money to build up this.Try this...

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Fire alarm circuit

Many fire alarm circuits are presented here,but this time a new circuit using a thermistor and a timer to do the trick. The circuit is as simple and straight forward so that , it can be easily implemented.The thermistor offers a low resistance at high temperature and high resistance at low temperature. This phenomenon is employed here for sensing the fire.


The IC1 (NE555) is configured as a free running oscillator at audio frequency. The transistors T1 and T2 drive IC1. The output(pin 3) of IC1 is couples to base of transistor T3(SL100), which drives the speaker to generate alarm sound. The frequency of NE555 depends on the values of resistances R5 and R6 and capacitance C2.When thermistor becomes hot, it gives a low-resistance path for the positive voltage to the base of transistor T1 through diode D1 and resistance R2. Capacitor C1 charges up to the positive supply voltage and increases the the time for which the alarm is ON. The larger the value of C1, the larger the positive bias applied to the base of transistor T1 (BC548). As the collector of T1 is coupled to the base of transistor T2, the transistor T2 provides a positive voltage to pin 4 (reset) of IC1 (NE555). Resistor R4 is selected s0 that NE555 keeps inactive in the absence of the positive voltage. Diode D1 stops discharging of capacitor C1 when the thermistor is in connection with the positive supply voltage cools out and provides a high resistance path. It also inhibits the forward biasing of transistor T1.

Notes.

* The circuit can be powered from a 6V battery or a 6V power supply.
* The thermistor can be mounted on a heat resistant material like mica to prevent it from damage due to excessive heat.
* The LED acts as an indication when the power supply is switched ON.

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Remote toggle switch circuit

The only difference is in the approach. This
circuit is designed by using another method. Using this circuit you can
toggle any electrical appliance between ON and OFF states by using
your TV remote. The only requirement is that your TV remote should be
operating in the 38 KHz.

 The IC1 (TSOP 1738)
is used to receive the infrared signals from the remote. When no IR
signal from remote is falling on IC1, its output will be high. When the
IR signal from the remote falls on the IC1, its output goes low. This
triggers the IC2 which is wired as a monostable multivibrator.The
output of the IC2 (pin6) goes high for a time of 1S (set by the values
of R2 and C3.This triggers the flip flop (IC2) and its Q output (pin
15) goes high. This switches on the transistor, which activates the
relay and the appliance connected via relay is switched ON. For the
next press of remote the IC1 will be again triggered which in turn
makes the IC2 to toggle its output to low state. The load will be
switched OFF. This cycle continues for each press of the remote. The
pin 6 and pin 4 of IC1 are shorted to avoid false triggering.The diode
D1 can be used as a freewheeling  diode.

Circuit diagram with Parts list.

Notes.

• Assemble the circuit on a good quality PCB or common board.
• The circuit can be powered from  a 5V DC regulated power supply.
• The capacitors must be rated 15 V.
• The IC1&IC2 must be mounted on holders.
• The
  current capacity  of relay determines the load circuit can switch.Use a
  high amperage(`10A or above) relay for driving large loads like
  motor,heater etc.

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Garage Timer Circuit Diagram

The circuit described here is a testament to the ingenuity of two young designers from  a specialist  technical secondary school. The ‘garage timer’ began as a school electronics project and has now made it all the way to publication in our Summer Circuits special issue of Elektor Electronics. The circuit demonstrates that the application possibilities for the 555 and 556 timer ICs are by no means exhausted. So what exactly is a ‘garage timer’?

When the light switch in the garage is pressed, the light in the garage comes on for two minutes. Also, one minute and forty-five  seconds  after  the  switch is pressed, the outside light also comes on for a period of one minute. The timer circuit is thus really two separate timers. Although the circuit for the interior light timer is relatively straightforward, the exterior light timer has to deal with two time intervals. First the 105 second period must expire; then the exterior light is switched on, and after a further 60 seconds the light is turned off. To realise this sequence of events, a type 556 dual timer device, a derivative of the 555, is used.

Circuit diagram:

Garage Timer Circuit Diagram

The first of the two timers triggers the second after a period of 105 seconds. The second timer is then active for 60 seconds,and it is this timer that controls the exterior light. The interior light timer is triggered at the same moment as the dual timer. In this case a simple 555 suffices, with an output active for just two minutes from the time when the switch is pressed. Push-button S1 takes over the role of the wall-mounted light switch, while S2 is provided to allow power to be removed from the whole circuit if necessary. The circuit could be used in any application where a process must be run for a set period after a certain delay has expired.

For the school project the two garage lights are simulated using two LEDs. This will present no obstacle to experienced hobbyists, who will be able to extend the circuit, for example using relays, to control proper lightbulbs. The principles of operation of type 555 and 556 timers have been described in detail previously in Elektor Electronics, but we shall say a few words about the functions of Ic1a, IC1b and IC2.

When S1 is pressed (assuming S2 is closed!) the trigger inputs of both IC1a and IC2 are shorted to ground, and so the voltage at these inputs (pins 6 and 2 respectively) falls to 0 V.  The outputs of IC1a and IC2 then go to logic 1, and D2 (the interior light) illuminates. Capacitors  C1  and  C8  now  start  to charge via P1 and R2, and R8 and P3 respectively. When the voltage on C8 reaches two thirds of the supply voltage, which happens after 120 seconds, the output of IC2, which is connected as a monostable multivibrator, goes low. D2 then goes out. This accounts for the interior light function.

Likewise, 105 seconds after S1 is closed, the voltage on C1 reaches two thirds of the supply voltage and the output of Ic1a goes low. Thanks to C4, the trigger input of IC1b now receives a brief pulse to ground, exactly as IC1a was triggered by S1. The second monostable, formed by IC1b, is thus triggered. Its pulse duration is set at one minute, determined by C5, R5 and P2. D1 thus lights for one minute. Potentiometers P1, P2 and P3 allow the various time intervals to be adjusted to a certain extent.

If considerably shorter or longer times are wanted, suitable changes should be made to the values of C1, C5 and C8. The period of the monostable is given by the formula T = 1.1 RC where T is the period in seconds, R the total resistance in ohms, and C the capacitance in farads.

Author :Daniel Lomitzky and Mikolajczak Tyrone  Copyright :Electro

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Morning Alarm Circuit Diagram Using LDR

Description

          Circuit showing a morning alarm.Here we have used a switching transistor.When the sun rise up ldr is low resistance so the ldr is conduct and a positive volt coming to the base of the Q1 there for the transistor will switch.This time  the buzzer is ON . Adjust the preset control the intensity of light.Manually cut off the power.Are you interested please comment and join this site


Component Required

                Resistor  4.7k preset  , LDR

                Transistor   BC 548

                Buzzer




Source by : http://www.electronics-circuits.in/2012/01/morning-alarm.html

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Solar Charger Circuit Project Using Transistors

A very simple solar charger circuit project can be designed using few external electronic parts . This simple solar charger circuit is capable of handling charge currents of up to 1A. Alternate component values are given in the figure for lower current applications.

Solar Charger Circuit Project Using Transistors circuit diagram :

The only adjustment is the voltage trip point when the current is shunted through the transistor and load resistor. This should be set with a fully charged battery. As the transistor and R3 have the entire panel’s output across them when the battery is fully charged, all of the current from the panel will be going through R3 and the Darlington transistor TIP112, so these must be well heat sunk. Adjust R1 for the trip point, usually 14.4 V – 15 V for a 12 V SLA or a 12 V Ni-Cd battery.

Source : http://www.ecircuitslab.com/2011/06/solar-charger-circuit-project-using.html

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Remote Operated Home Appliances Circuit

Here is the circuit diagram of Remote Operated Home Appliances or
Remote controlled Home appliances. Connect this circuit to any of your
home appliances (lamp, fan, radio, etc) to make the appliance turn
on/off from a TV, VCD, VCR, Air Conditioner or DVD remote control. The
circuit can be activated from up to 10 meters. It is very easy to build
and can be assembled on a veroboard or a general-purpose PCB.

Circuit diagram:

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Logic Probe With Sound Circuit

This logic probe can be selected to operate on TTL or CMOS logic levels, depending on switch S1. A string of resistors associated with switch S1 sets the threshold levels for a window comparator comprising IC1a and IC1b. Depending on whether the level applied to the probe is high or low, the window comparator turns on LED1 (high) or LED2 (low). The 1.2M and 680k resistors set the probe signal to a midrange value when the probe is open-circuit, thereby preventing either LED from being lit.

Circuit diagram:

Logic Probe With Sound Circuit digram

If a pulse signal is present, the output of IC1a will toggle the clock input of flipflop IC2a. This drives LED3 which either lights for each pulse or continuously, depending on the setting of switch S2. Finally, the outputs of IC1a & IC1b are connected by diodes D5 & D6 to the base of transistor Q1 which is connected to the Reset input of flipflop IC2b. This has a piezo sounder (not buzzer) connected between its Q and Q-bar outputs so that it produces a sound which echoes the input pulse signal.

Author: Tom Hughes Copyright: Silicon Chip Electronics

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Band Graphic Equalizer Circuit Diagram Design Lmc835

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