Micro Inverter circuit DC voltage AC 12v x110v

This is a micro-inverter DC voltage to AC from a 12v battery can generate a voltage of 110 or 220 volts AC and a frequency of 50Hz to 60Hz.

Micro Inverter circuit DC voltage AC 12v x110v Circuit Diagram:

Inverter Circuit Diagram

The circuit is very simple and does not need a printed circuit board, It is composed of two transistors oscillators that generate the square wave pulse to the transformer in the case is 10 +10 and its output 220V or 110V. This circuit is 50Hz, but can be changed by changing the value of RC .

Circuit Diagram

This circuit has the power transistor and that depends on the transformer.

source by: w3circuits

Low-cost and HiFi Expandor

This is the schematic design of HiFi Expandor Circuit with De-emphasis. The circuit is based NE570. The NE570 can be used to construct a high performance compandor suitable for use with music. This type of system can be used for noise reduction in tape recorders, transmission systems, bucket brigade delay lines, and digital audio systems. The circuits to be described contain features which improve performance, but are not required for all applications.

HiFi Expandor Circuit Diagram:
Expandor Circuit Diagram

The expandor to complement the compressor is shown in the above circuit. Here an external op amp is used for high slew rate. Both the compressor and expandor have unity gain levels of 0dB. Trim networks are shown for distortion (THD) and DC shift. The distortion trim should be done first, with an input of 0dB at 10kHz. The DC shift should be adjusted for minimum envelope bounce with tone bursts. When applied to consumer tape recorders, the subjective performance of this system is excellent.

250W Inverter using 555 timer IC1

Here is a simple circuit diagram of 250w inverter. 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:

Inverter Circuit Diagram

Low Loss Step Down Converter

This circuit arose from the need of the author to provide a 5 V output from the 24 V battery of a solar powered genera-tor. Although solar power is essentially free it is important not to be wasteful especially for small installations; if the battery runs flat at midnight you’ve got a long wait before the sun comes up again. The basic requirement was to make an efficient step-down converter to power low voltage equipment; the final design shown here accepts a wide input voltage from 9 to 60 V with an output current of 500 mA. The efficiency is very good even with a load of 1 mA the design is still better than a standard linear regulator. The low quiescent current (200 µA) also plays a part in reducing losses.
Some of the components specified (particularly the power MOSFET) are not the most economical on the market but they have been deliberately selected with efficiency in mind.
Circuit diagram :

Low Loss Step Down Converter

Low Loss Step Down Converter Circuit Diagram
When power is applied to the circuit a reference voltage is produced on one side of R2. D1 connects this to the sup-ply (pin 7) of IC1 to provide power at start-up. Once the circuit begins switching and the output voltage rises to 5 V, D2 becomes forward biased and powers the IC from the output. Diode D1 becomes reverse biased reducing current through R1. When the circuit is first powered up the voltage on pin 2 of IC1 is below the reference voltage on pin 3, this produces a high level on output pin 6. The low power MOSFET T1 is switched on which in turn switches the power MOSFET T3 via R5 and the speed-up capacitor C4, the output volt-age starts to rise.
When the output approaches 5 V the voltage fed back to the inverting input of IC1 becomes positive with respect to the non inverting input (reference) and switches the output of IC1 low. T1 and T3 now switch off and C3 transfers this negative going edge to the base of T2 which conducts and effectively shorts out the gate capacitance of T3 thereby improving its switch off time.
The switching frequency is not governed by a fixed clock signal but instead by the load current; with no load attached the circuit oscillates at about 40 Hz while at 500 mA it runs at approximately 5 kHz. The variable clock rate dictates that the output inductor L1 needs to have the relatively high value of 100 mH. The coil can be wound on ferrite core material with a high AL value to allow the smallest number of turns and produce the lowest possible resistance. Ready-made coils of this value often have a resistance greater than 1 ? and these would only be suitable for an output load current of less than 100 mA.
The voltage divider ratio formed by R4 and R3 sets the output voltage and these values can be changed if a different out-put voltage is required. The output volt-age must be a minimum of 1 V below the input voltage and the output has a minimum value of 4 V because of the supply to IC1.
A maximum efficiency of around 90 % was achieved with this circuit using an input voltage between 9 and 15 V and supplying a current greater than 5 mA, even with an input voltage of 30 V the circuit efficiency was around 80 %. If the circuit is used with a relatively low input voltage efficiency gains can be made by replacing D4 with a similar device with a lower reverse breakdown voltage rating, these devices tend to have a smaller for-ward voltage drop which reduces losses in the diode at high currents. At higher input voltage levels the value of resistor R1 can be increased proportionally to reduce the quiescent current even further.
Author : Michel Franke - Copyright : Elektor

Automatic AC Power Switch

Electrical appliances accidentally left on  in (holiday) homes left unoccupied for a  short or a long period consume power  unnecessarily and can present a fire hazard. Everyone will be familiar with those  nagging thoughts, a few miles down the  road from the house: “Did I remember  to switch off the coffee machine? The  lights? The oven?”
Automatic AC Power Switch Circuit Diagram:
Switch Circuit Diagram

Hotel rooms are often equipped with a  switch near the main door which enables the power supply to everything in  the room only when the plastic card (which  might contain a chip or have a magnetic strip  or a pattern of holes) that serves as the room  key is inserted. The circuit idea given here  to switch off lights and other appliances is  along the same lines. The solution is surprisingly simple.

A reed contact is fitted to the frame of the main entrance door, and a matching magnet  is attached to the door itself such that when  the door is closed the reed contact is also  closed. To enable power to the house, press  S1 briefly. Relay RE1 will pull in and complete  the circuit for all the AC powered appliances in  the house. The relay will be held in even after  the button is released via the second relay contact and the reed contact (‘latching’ function).
As soon as the main entrance door is  opened, the reed contact will also open.  This in turn releases the latch circuit and  consequently the relay drops out. The  various connected appliances will thus  automatically and inevitably be switched  off as soon as the house is left. The circuit is principally designed for  small holiday homes, where this mode  of operation is particularly practical. Of course, for any circuit that deals in AC  powerline voltages, we must mention  the following caution.
shock hazard! Construction and connection of this circuit  should only be carried out by suitably-qualified  personnel, and all applicable electrical safety  regulations must be observed. In particular, it  is essential to ensure that the relay chosen is  appropriate for use at domestic AC grid volt-ages and is suitably rated to carry the required  current.
Author : Stefan Hoffmann – Copyright : Elektor

0-30 Volt Laboratory Power Supply

The linear power supply, shown in the schematic, provides 0-30 volts, at 1 amp, maximum, using a discrete transistor regulator with op-amp feedback to control the output voltage. The supply was constructed in 1975 and has a constant current mode that is used to recharge batteries.
0-30 Volt Laboratory Power Supply Circuit Diagram:
0-30 Volt Laboratory Power Supply Circuit Diagram

With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum supply voltage to the op-amps supply pins. D5, C4, C5, R15, and R16 provide a small amount of negative supply for the op-amps so that the op-amps can operate down to zero volts at the output pins (pins 6).

A more modern design might eliminate these 4 components and use a CMOS rail-to-rail op-amp. Current limit is set by R3, D1, R4, R6, Q12, R10, and R13 providing a bias to U2 that partially turns off transistors Q9 and Q11 when the current limit is reached. R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), and R11 is an internal trim-pot for calibration. The meter is a 1 milliamp meter with an internal resistance of 40 ohms. Switch S1 determines whether the meter reads 0-30 volts, or 0-1 amp.
A more modern circuit might use a single IC regulator, such as the MC78XX, or MC79XX series, immediately after the half wave rectifier, to replace approximately 30 components, or at least a high precision zener diode to replace D10 as the voltage reference. The LM4040 is one such voltage reference and has excellent stability over temperature. IC regulators such as the MC78XX series may eventually become obsolete as newer IC regulators are designed, however, discrete transistors, op-amps, and zeners are more generic, have a longer production lifespan, and allow the designer to demonstrate that he understands the principles of linear regulated power supply operation.