You can read books at night under a light. Energy from AC main makes it happen. But if you do not have an AC voltage. Do You still use a light? You need to use a 100w Inverter circuit and battery. Also, If you are outside a house, no electricity. You cannot use a lamp with a 12V battery.
This circuit is a mini inverter circuit using power transistor 2N3055 as the main component without IC.
It is designed for you that need to use appliances outdoor or no electricity. Someone use it in a car or the high mountain etc.
It can be converted 12VDC to 220VAC. The maximum output power about 100 watts. It is suitable for normal lighting (all home lamps), also used for radio, LCD TV, Stereo.
Someone uses it for a small soldering iron to repair or build many projects outdoor home.
How 100W inverter circuit works
See the circuit diagram below
Figure 1, 100w Inverter circuit, 12V to 220VAC using transistors
This circuit will include five main sections as a block diagram.
1. Q1 and Q2 act as the frequency oscillator circuit.
2. Q3 and Q4 act as the frequency divider circuit
3. Q5 and Q6 act as the transistor driver circuit.
4. Q7 and Q8 act as the output power amplifier circuit.
5. T1 is a voltage converter to power a load.
Here is a step-by-step process.
First, both PNP transistors Q1, Q2 will be connected together as the astable multivibrator form. They will generate the output frequency of about 100 Hz at the collector lead of Q2.
This frequency is set by both resistors R1, R2, and two capacitors C1, C2. And there are both diodes D1, D2 to set only positive voltage through the emitter lead of Q1, Q2.
Then, this signal flows through to the frequency divider by two. It makes the frequency is reduced down to about 50Hz.
Why designer does not set the circuit to directly work at 50 Hz. Because generating the steady low frequency is too hard.
This frequency has value the same as the AC main.
It will be a waveform of low-power alternating current. And, out to the collector leads of transistors Q3, Q4. Then, via resistors R8, R9, and R11, R12.
They are a voltage divider circuit to biased for driver transistors Q5 and Q6. To drive the power transistors Q7, Q8 alternately power the high current to the inductance coil in the transformer T1. It will induce electrical energy through the metal core from a set of 12V coils to an AC voltage of 220V at 50Hz to 60Hz for further use.
1. Normally, use the 2-3A transformers for 20 watts to 30watts for light bulbs. But you want 100 watts, you must use an 8A transformer. It is so expensive for me.
2. The primary coil of a transformer, you may use 9V CT 9V or 10V CT 10V or 12V CT 12V.
If you use a 9V CT 9V transformer. The output voltage will be 250V (approx).
Which normal I use 12V CT 12V, makes the output voltage about AC 220V (no-load). But with load, the voltage will reduce to AC 190V
3.This circuit will have output as a square waveform. So cannot use for inductor load.
But it’s enough for mini electrical appliances. Such as electric soldering iron, Digital TV, Mobile Charger, Small laptop, etc.
4. This transformer, we may use a secondary coil as the output voltage as you need. The example we connect to the power amplifier that uses AC 24 volts. So we use AC 24V secondary coil, etc.
How to builds
Similar to the various projects that have passed. To begin with, make the PCB or you can use the universal PCB(Perforated PCB). Then, assemble all parts on PCB as Fig. Next check all for errors. Check again and check again.
Then, apply the 12V 10A battery to this circuit. And use the voltmeter to measure AC voltage output. Next, connects the load to the circuit. is it easy?
PCB layout and components layouts of the 100w Inverter circuit, 12V to 220V using Transistors
Parts you will need
Q1-Q4: BC557, 45V 100mA PNP Transistor
Q5, Q6: BD139, 80V 1.5A NPN Transistor
Q7, Q8: 2N3055, 100V, 15A, 115W, >2,5MHz NPN transistor
D1, D2, D3, D4: 1N4148, 75V 150mA Diodes
D5, D6: 1N4007, 1000V 1A Diodes
0.5W Resistors tolerance: 5%
R1, R4, R6, R7: 10K
R2, R3: 150K
R5, R6: 47K
R9, R12: 220 ohms
R10, R13: 560 ohms
R11, R14: 100K
R17, R18: 150 ohms
R15, R16: 10 ohms, 10W Resistors tolerance: 5%
C1,C2: 0.047uF 50V
C3,C4: 0.01uF 50V
C5: 1uF 50V
C6: 0.1uF 250VAC
C7: 0.1uF 50V
C8: 220uF 25V, Electrolytic capacitors
T1: 220V/120V AC primary to 12V-0-12V,2-8A secondary transformer.
Be careful connecting components
Are components backward? You must connect them in proper pins only. Look at connecting correctly capacitors, Diodes, Diodes, transistors, etc.
For 2N3055 transistors, look at mounting it on the heatsink.
The screws should be tightened. Because a large amount of current flows through Pin C to Pin E.
All full-size images of this post are in this Ebook: Elec Circuit vol. 2 below. Please support me. 🙂
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