Simple 250W Inverter Circuit Diagram

This is the Simple 250W Inverter Circuit Diagram.In this time 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. 

Simple 250W Inverter Circuit Diagram

Simple 250W Inverter Circuit Diagram

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Light and Sound Indicator for Mains Power Supply Project

While repairing or installing electrical machines in a building, the AC mains power supply is switched off from the mains electrical switchboard installed outside the building. There is a chance that someone who is not aware of the same may switch on the mains from outside. This poses a great danger for the technician working inside. Hence, an indicator like the one described here, which can be plugged into a nearby mains wall socket, might prove very useful for the technician.

This circuit can also be useful for people who are living in a place where there is frequent mains power cut.

Circuit and working
The circuit diagram of the light and sound indicator for the mains power supply is shown Fig. 1. The circuit is built around capacitors C1 and C2, resistors R1 and R2, diode D1, zener diode ZD1, LED1 and a piezo buzzer (PZ1). Resistor R1 and capacitor C1 are used for reducing the voltage and limiting the current. Diode D1 is a rectifier.

C2 is used as a filtering capacitor. Zener diode ZD1 limits the output voltage to around 12V. The value of zener diode should be equal to or lower than the maximum voltage of the buzzer and higher than the minimum voltage. Preferably, the buzzer should have a built-in oscillator working in the range of 6V-12V and requiring a current below 10mA. The frequency of the alarm sound is usually in several kilohertz (kHz).

LED1 is on when the mains power supply is present, and at the same time the buzzer produces sound. Resistor R1, capacitor C1 and diode D1 are selected depending on the current requirement of the buzzer.

Circuit diagram of the mains power indicator
Fig. 1: Circuit diagram of the mains power indicator

Fig. 2: Actual-size, single-side PCB of the indicator

Fig. 3: Component layout of the indicator

Construction and testing
An actual-size, single-side PCB of the simple light and sound indicator is shown in Fig. 2 and its component layout in Fig. 3. Enclose the PCB in a suitable small box in such a way that you can use it during repair work or installation. Ensure proper wiring to avoid any mistake.

Sourced by: EFY

Petre Tzv Petrov was a researcher and assistant professor in Technical University of Sofia, Bulgaria, and expert-lecturer in OFPPT, Casablanca, Kingdom of Morocco. He is currently working as an electronics engineer in the private sector in Bulgaria

Glass Break Alarm Circuit Diagram

This circuit can be used for sounding an alarm to detect the breaking of a glass window by an intruder, even when the intruder ensures there is no sound of the shattered glass.

Fig. 1: Circuit of the glass break alarm
Fig. 1: Circuit of the glass break alarm

Circuit and working
Fig. 1 shows the circuit diagram of the glass break alarm. It is built around a piezo element connected across connector CON2, transistor BC549 (T1), timer NE555 (IC1), a piezo buzzer (PZ1) and a few other components.

A small piezo element used in the piezo buzzer is used as a sensor. It may be fixed at the centre of the window glass. IC1 is wired in monostable multivibrator mode, which is triggered by the piezo element. Output of IC1 is used to drive piezo buzzer PZ1. LED1 indicates the high-state output at pin 3 of IC1. Time delay can be adjusted by potentiometer VR1. Use an ordinary piezo buzzer at the output to generate a warning sound. This circuit works on 9V-12V DC.

When an intruder tries to break the glass, the piezo element generates an electric pulse, which is amplified and sent to the monostable multi-vibrator (IC1). The high output of IC1 drives LED1 and also produces a sound to indicate that someone is breaking the glass.

The 9V-12V DC power supply is connected across CON1, and the piezo element is connected across connector CON2.

Construction and testing
An actual-size, single-side PCB for the glass break alarm is shown in Fig. 2 and its component layout in Fig. 3. Enclose the PCB in a suitable small box in such a way that the piezo buzzer sounds when someone tries to break the glass window. Fix the piezo element at the centre of the window glass for best results.

Fig. 2: Actual-size PCB of the glass break alarm

Fig. 3: Component layout of the PCB

Use of 8-pin IC base is recommended for IC NE555.

Sourced by: EFY. Author : Pradeep G.

Automatic Dipper for Vehicles Project

While driving a car in night a problem like many drivers do not dip the head lamps of their vehicles in night while approaching. The several switching operation is used to dip the head light which may distract the concentration. To overcome this type of problem the innovative group Dreamlover Technology designs a unique electronics gadget called “Automatic Dipper” using very popular IC NE555 and LDR.

Circuit Description

The entire circuit of automatic dipper consist LDR followed by timer IC NE555 (IC1) and few other components, where LDR is used as sensor. LDR sense the light and change its internal resistance according light fall on it, which is further mounted in PVC pipe of 4 cm length positioned on the grill of car or in front such that the light fall on the LDR only when vehicles is approaching and is distance of 3M to 9M. When light fall on it the resistance decrease and makes output of IC1 low which energized the relay. The relay operates and voltage across the head lamps is reduced. When the distance between two approaching vehicles is more than 9 meter or less than 3 meter the circuit is not operated.

Automatic Dipper for Vehicles Circuit Diagram 

Automatic Dipper for Vehicles

The operating and non operating distance of the circuit can be varied by proper positioning of the PVC pipe and by adjusting the variable resistor VR1.

Resistors (all ¼-watt, ± 5% Carbon)

R1 = 10 Ω/10W

VR1 = 10 KΩ

IC1 = NE555 (timer IC)

D1 = 1N4001

RL1 = 12V/100 Ω

LDR1= Light dependent resistor

Sourced by:  electronicsproject

Electronic siren circuit Diagram

This is a compact electronic siren circuit based on three transistors.This circuit is suitable for in corporating with other alarm or siren projects such as burglar alarms, automatic factory sirens etc or a simple push to on alarm.

The  electronic siren circuit given here  is  based on a complementary transistor pair consisting of Q2 & Q3 (BC557 & BC 37)  wired as an astable multivibrator oscillator,which directly drives the speaker.The transistor Q1 is used to provide a full charge on capacitor C2 when power is turned ON. When push button switch S1 is pressed , the capacitor C2 slowly discharges through resistor R8.This makes the circuit to  oscillate at a low frequency that increases to a high frequency and kept indefinitely as the capacitor is fully discharged. When the switch P1 is released, the output  frequency decreases slowly as C2 is charged to the  positive voltage through resistance R6 and the Base-Emitter junction of tramsistor Q2. When C2 is fully charged to the positive battery voltage the  circuit stops oscillating.

Electronic siren circuit Diagram with Parts list.

Electronic siren circuit Diagram


  • A 12 V battery or a a well regulated 12V DC power supply can be used to power the circuit.
  • Assemble the circuit on a good quality PCB or common board.
  • The switch S1 can be used to activate the alarm.
  • The switch S2 can be used as a power switch.
  • You can experiment on the tone of alarm by using different values for C2 and R8.

Sourced By: circuitstoday