Interested to make your own power inverter with built in charger? A simple 400 watt inverter circuit with charger that can be very easily built and optimized has been provided in this article. Read the complete discussion through neat illustrations.

A massive 400 watts power inverter with built in charger circuit has been thoroughly explained in this article through circuit schematics. A simple calculation to evaluate the transistor base resistors has also been discussed.

I have discussed the construction of a few good inverter circuits through some of my previous articles and am truly excited by the overwhelming response that I am receiving from the readers. Inspired by the popular demand I have designed yet another interesting, more powerful circuit of a power inverter with built in charger.

The present circuit though similar in operation, is more interesting and advanced due to the fact that it has got a built-in battery charger and that too fully automatic.

As the name suggests the proposed circuit will produce a massive 400 watts (50 Hz) of power output from a 24 volt truck battery, with an efficiency as high as 78%.

As it’s fully automatic, the unit may be permanently connected to the AC mains. As long as the input AC is available, the inverter battery is continuously charged so that it is always kept in a topped up, standby position.

As soon as the battery becomes fully charged an internal relay toggles automatically and shifts the battery into the inverter mode and the connected output load is instantly powered through the inverter.

The moment the battery voltage falls below the preset level, the relay toggles and shifts the battery into the charging mode, and the cycle repeats.

Without wasting anymore time let’s straightaway move into the construction procedure.

You will require the following parts for the construction of the inverter circuit:

All resistors are ¼ watt, CFR 5%, unless otherwise stated.

R1----R6 = To be calculated - Read at the end of the article

R7 = 100K (50Hz), 82K (60Hz)

R8 = 4K7,

R9 = 10K,

P1 = 10K,

C1 = 1000Âµ/50V,

C2 = 10Âµ/50V,

C3 = 103, CERAMIC,

C4, C5 = 47Âµ/50V,

T1, 2, 5, 6 = BDY29,

T3, 4 = TIP 127,

T8 = BC547B

D1-----D6 = 1N 5408,

D7, D8 = 1N4007,

RELAY = 24 VOLT, SPDT

IC1 - N1, N2, N3, N4 = 4093,

IC2 = 7812,

INVERTER TRANSFORMER = 20 – 0 – 20 V, 20 AMPS. OUTPUT = 120V (60Hz) OR 230V (50Hz),

CHARGING TRNASFORMER = 0 – 24V, 5 AMPS. INPUT = 120V (60Hz) OR 230V (50Hz) MAINS AC

We already know that an inverter basically consists of an oscillator which drives the subsequent power transistors which in turn switches the secondary of a power transformer alternately from zero to the maximum supply voltage, thus producing a powerful stepped up AC at the primary output of the transformer.

In this circuit IC 4093 forms the main oscillating component. One of its gates N1 is configured as an oscillator, while the other three gates N2, N3, N4 are all connected as buffers.

The oscillating outputs from the buffers are fed to the base of the current amplifier transistors T3 and T4. These are internally configured as Darlington pairs and increase the current to a suitable level.

This current is used to drive the output stage made up of power transistors T1, 2, 5 and 6.

These transistors in response to its alternating base voltage are able to switch the entire supply power into the secondary winding of the transformer to generate an equivalent level of AC output.

The circuit also incorporates a separate automatic battery charger section.

The construction part of this project is pretty straightforward and may be completed through the following easy steps:

Begin the construction by fabricating the heat sinks. Cut two pieces of 12 by 5 inches of aluminum sheets, having a thickness of Ã‚½ cm each.

Bend them to form two compact “C” channels. Drill accurately a pair of TO-3 sized holes on each heat sink; fit the power transistors T3---T6 tightly over the heat sinks using screws, nuts and spring washers.

Now you may proceed for the construction of the circuit board with the help of the given circuit schematic. Insert all the components along with the relays, interconnect their leads and solder them together.

Keep transistors T1 and T2 little aloof from the other components so that you may find sufficient space to mount the TO-220 type of heat sinks over them.

Next go on to interconnect the base and emitter of the T3, 4, 5 and T6 to the appropriate points on the circuit board. Also connect the collector of these transistors to the transformer secondary winding using thick gauge copper wires (15 SWG) as per the shown circuit diagram.

Clamp and fix the whole assembly inside a well ventilated strong metallic cabinet. Make the fittings absolutely firm using nuts and bolts.

Finish the unit by fitting the external switches, mains cord, output sockets, battery terminals, fuse etc. over the cabinet.

This concludes the construction of this power inverter with built in charger unit.

The value of the base resistor for a particular transistor will largely depend on its collector load and the base voltage. The following expression provides a straightforward solution to calculate accurately the base resistor of a transistor.

R1= (Ub - 0.6)*Hfe / ILOAD

Here Ub = source voltage to R1,

Hfe = Forward current gain (for TIP 127 it’s more or less 1000, for BDY29 its around 12)

ILOAD = Current required to activate fully the collector load.

So, now calculating the base resistor of the various transistors involved in the present circuit becomes pretty easy. It is best done with the following points.

We start first by calculating the base resistors for the BDY29 transistors.

As per the formula, for this we will need to know ILOAD, which here happens to be the transformer secondary one half winding. Using a digital multimeter, measure the resistance of this portion of the transformer.

Next, with the help of Ohms law, find the current (I) that will pass through this winding (Here U = 24 volts).

R = U/I or I = U/R = 24/R

## Introduction

A massive 400 watts power inverter with built in charger circuit has been thoroughly explained in this article through circuit schematics. A simple calculation to evaluate the transistor base resistors has also been discussed.

I have discussed the construction of a few good inverter circuits through some of my previous articles and am truly excited by the overwhelming response that I am receiving from the readers. Inspired by the popular demand I have designed yet another interesting, more powerful circuit of a power inverter with built in charger.

The present circuit though similar in operation, is more interesting and advanced due to the fact that it has got a built-in battery charger and that too fully automatic.

As the name suggests the proposed circuit will produce a massive 400 watts (50 Hz) of power output from a 24 volt truck battery, with an efficiency as high as 78%.

As it’s fully automatic, the unit may be permanently connected to the AC mains. As long as the input AC is available, the inverter battery is continuously charged so that it is always kept in a topped up, standby position.

As soon as the battery becomes fully charged an internal relay toggles automatically and shifts the battery into the inverter mode and the connected output load is instantly powered through the inverter.

The moment the battery voltage falls below the preset level, the relay toggles and shifts the battery into the charging mode, and the cycle repeats.

Without wasting anymore time let’s straightaway move into the construction procedure.

**Parts List for the circuit diagram**You will require the following parts for the construction of the inverter circuit:

All resistors are ¼ watt, CFR 5%, unless otherwise stated.

R1----R6 = To be calculated - Read at the end of the article

R7 = 100K (50Hz), 82K (60Hz)

R8 = 4K7,

R9 = 10K,

P1 = 10K,

C1 = 1000Âµ/50V,

C2 = 10Âµ/50V,

C3 = 103, CERAMIC,

C4, C5 = 47Âµ/50V,

T1, 2, 5, 6 = BDY29,

T3, 4 = TIP 127,

T8 = BC547B

D1-----D6 = 1N 5408,

D7, D8 = 1N4007,

RELAY = 24 VOLT, SPDT

IC1 - N1, N2, N3, N4 = 4093,

IC2 = 7812,

INVERTER TRANSFORMER = 20 – 0 – 20 V, 20 AMPS. OUTPUT = 120V (60Hz) OR 230V (50Hz),

CHARGING TRNASFORMER = 0 – 24V, 5 AMPS. INPUT = 120V (60Hz) OR 230V (50Hz) MAINS AC

### Circuit Functioning

We already know that an inverter basically consists of an oscillator which drives the subsequent power transistors which in turn switches the secondary of a power transformer alternately from zero to the maximum supply voltage, thus producing a powerful stepped up AC at the primary output of the transformer.

In this circuit IC 4093 forms the main oscillating component. One of its gates N1 is configured as an oscillator, while the other three gates N2, N3, N4 are all connected as buffers.

The oscillating outputs from the buffers are fed to the base of the current amplifier transistors T3 and T4. These are internally configured as Darlington pairs and increase the current to a suitable level.

This current is used to drive the output stage made up of power transistors T1, 2, 5 and 6.

These transistors in response to its alternating base voltage are able to switch the entire supply power into the secondary winding of the transformer to generate an equivalent level of AC output.

The circuit also incorporates a separate automatic battery charger section.

### How to Build?

The construction part of this project is pretty straightforward and may be completed through the following easy steps:

Begin the construction by fabricating the heat sinks. Cut two pieces of 12 by 5 inches of aluminum sheets, having a thickness of Ã‚½ cm each.

Bend them to form two compact “C” channels. Drill accurately a pair of TO-3 sized holes on each heat sink; fit the power transistors T3---T6 tightly over the heat sinks using screws, nuts and spring washers.

Now you may proceed for the construction of the circuit board with the help of the given circuit schematic. Insert all the components along with the relays, interconnect their leads and solder them together.

Keep transistors T1 and T2 little aloof from the other components so that you may find sufficient space to mount the TO-220 type of heat sinks over them.

Next go on to interconnect the base and emitter of the T3, 4, 5 and T6 to the appropriate points on the circuit board. Also connect the collector of these transistors to the transformer secondary winding using thick gauge copper wires (15 SWG) as per the shown circuit diagram.

Clamp and fix the whole assembly inside a well ventilated strong metallic cabinet. Make the fittings absolutely firm using nuts and bolts.

Finish the unit by fitting the external switches, mains cord, output sockets, battery terminals, fuse etc. over the cabinet.

This concludes the construction of this power inverter with built in charger unit.

### How to Calculate Transistor Base Resistor for Inverters

The value of the base resistor for a particular transistor will largely depend on its collector load and the base voltage. The following expression provides a straightforward solution to calculate accurately the base resistor of a transistor.

R1= (Ub - 0.6)*Hfe / ILOAD

Here Ub = source voltage to R1,

Hfe = Forward current gain (for TIP 127 it’s more or less 1000, for BDY29 its around 12)

ILOAD = Current required to activate fully the collector load.

So, now calculating the base resistor of the various transistors involved in the present circuit becomes pretty easy. It is best done with the following points.

We start first by calculating the base resistors for the BDY29 transistors.

As per the formula, for this we will need to know ILOAD, which here happens to be the transformer secondary one half winding. Using a digital multimeter, measure the resistance of this portion of the transformer.

Next, with the help of Ohms law, find the current (I) that will pass through this winding (Here U = 24 volts).

R = U/I or I = U/R = 24/R

- Divide the answer with two, because the current of each half winding gets divided through the two BDY29s in parallel.
- As we know that the supply voltage received from the collector of TIP127 will be 24 volts, we get the base source voltage for BDY29 transistors.
- Using all the above data we can now very easily calculate the value of the base resistors for the transistors BDY29.
- Once you find the value of the base resistance of BDY29, it will obviously become the collector load for TIP 127 transistor.
- Next as above using Ohms law, find the current passing through the above resistor. Once you get it, you may go on to find the value of the base resistor for the TIP 127 transistor simply by using the formula presented at the beginning of the article.
- The above explained simple transistor calculation formula may be used to find the value of the base resistor of any transistor involved in any circuit

**Need Help? Please send your queries through Comments for quick replies! And please Bookmark my site :)**

## Comments

i am a student a i want to connect my on 400w inverter circuit in my project pls i nit assistance from you sir.

what help do you need?

Though I know a little of electronics my knowledge is very limited.On seeing your " how to make a 400 Watt inverter I am tempted to try to do this. kindly guide about

inv on,p1,n/i n/o.What components I have to fit in there & their values.My email address is pramamurthister@gmail.com. Thanking you

P1 is a variable resistor or a preset.

N/O and N/C are the relay contacts.

Please note that the above circuit is not for newcomers, there's a big chance that you may fail to make it work due to lack of complete knowledge.

Yes you can use it.

try something simple, may be you can begin with the following design for learning:

https://homemade-circuits.com/2012/09/mini-50-watt-mosfet-inverter-circuit.html

I have already provided more than enough data in the car GSM article therefore I have stopped answering to comments under that article. The project is strictly for the experts in the field so anyway there's no point in making that project if you are not an expert.

Which inverter circuit are you referring to?

pls provide the link.

we connected the schmitt NAND gate circuit using IC4093 (vcc =+12v, vss =gnd) and gave 24v an input to first nand gate N1, through c1 and R8.. we obtained +12v at n4 gate output and 0v for n2 gate. we expect a square wave output. we got a pure dc output... what will be the actual output from the nand gates... please give your valuable suggestions.... as possible we started to do this inverter..... thank you

Please sir could you kindly post a circuit on 1000watt (1KVA) inverter.

Thank you in anticipation

i have already have this circuit in my blog, please use the search box to find it.

https://homemade-circuits.com/2012/07/simplest-and-best-100-watt-inverter.html

Please tell me what happen if we not connected 12v truck battery in this circuit,is it(12v battery) for giving solar power at night times ?also give information about cost.

Thanks&Regards

siva

Actually I wana make a 100 or 50 w inverter with inbuilt charger using 6v, 4.5 Ah battery plz suggest me the circuit

What type of simple Inverter can i desing to operate Fans, bulb, Soldering Iron and Tv/dvd?

Lets say, the one with 220v 50hz, 150watt.

I need your help on, partlist needed for the above invater construction.

Thanks!

https://homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html

1)if i use invertor transforMER 12-0-12/ 20amp or 30 amp & Charging transformer 0-12/3amp or 5 A

2) Battery voltage is 12v /100AH

3)What is the value of R1 to R6 ,i cannt calculate because of Iload? what is ILOAD value?

After using this ,the o/p will be 400w or not.If not what should made changes for this circuit?

Plsease reply.

ILOAD can be achieved by dividing the trafo wattage with the battery voltage, in your case that will be simply 20 amps I guess

i blow up already some tansistors

i use de dec3716 (5of them in 1 section) and the bdx53 in a little different confuguration

thanks

rinus

i'm stack with the calculations

pls help me

you can give me the values you use as an example

thanks

= (12 - 0.6)10 / 40 = 2.85 ohms

you can try 10 watt resistor.