A 50 watt inverter might look quite trivial, but it can serve some
useful purposes to you. When outdoors, this small power house can be used for
operating small electronic gadgets, soldering iron, table top radios,
incandescent lights, fans etc.
Let’s learn how to build this homemade 50 watt inverter unit, beginning
with a brief description regarding the circuit diagram and its
functioning:
Circuit Description
The circuit may be understood with the following points:
Referring to the figure, transistors T1 and T2 along with the other R1,
R2, R3 R4, C1 and C2 together form a simple astable multivibrator (AMV)
circuit. A multivibrator circuit basically is composed of two symmetrical half
stages, here its formed by the left and the right hand side transistor stages
which conduct in tandem or in simple words the left and the right stages
conduct alternately in a kind of a perpetual “motion”, generating a continuous flip
flop action.
The above action is responsible of creating the required oscillations
for our inverter circuit. The frequency of the oscillation is
directly proportional to the values of the capacitors or/and the resistors at
the base of each transistor.
Lowering the values of the capacitors increases the frequency while
increasing the values of the resistors decreases the frequency and vice versa.
Here the values are chosen so as to produce a stable frequency of 50 Hz.
Readers, who wish to alter the frequency to 60 Hz, may easily do it by
just changing the capacitor values appropriately.
Transistors T2 and T3 are placed at the two output arms of the AMV
circuit. These are high gain; high current Darlington paired transistors, used
as the output devices for the present configuration.
The frequency from the AMV is fed to the base of T2 and T3 alternately
which in turn switch the transformer secondary winding, dumping the entire
battery power in the transformer winding.
This results in a fast magnetic induction switching across the
transformer windings, resulting the required the mains voltage at the output of
the transformer.
Parts Required
You will require the following components for making this 50 watt
homemade inverter circuit:
R1, R2 = 100K,
R3, R4 = 330 Ohms,
R5, R6 = 470 Ohms, 2 Watt,
R7, R8 = 22 Ohms, 5 Watt
C1, C2 = 0.22 uF, Ceramic Disc,
D1, D2 = 1N5402 or 1N5408
T1, T2 = 8050,
T3, T4 = BC316,
T5, T6 = 2N3055 (TO-220)
General purpose PCB = cut into the desired size, approximately 5 by 4
inches should suffice.
Battery: 12 volts, Current not less than 10 AH.
Transformer = 9 – 0 – 9 volts, 5 Amps, Output winding may be 220 V or
120 volts as per your country specifications
Sundries: Metallic box, fuse holder, connecting cords, sockets etc
Testing and Setting Up the Circuit
After you finish making the above explained inverter circuit, you may do
the testing of the unit in the following manner:
Initially do not connect the transformer or battery to the circuit.
Using a small DC power supply power the circuit.
If everything is done rightly, the circuit should start oscillating at
the rated frequency of 50 Hz.
You can check this by connecting the prods of a frequency meter across
T3’s or T4’s collector and the ground. The positive of the prod should go to
the collector of the transistor.
If you don’t own a frequency meter, never mind, you do a rough checking
by connecting a headphone pin across the above explained terminals of the
circuit. If you hear a loud humming sound, will prove that your circuit is
generating the required frequency output.
Now it’s time to integrate the battery and the transformer to the above
circuit.
Connect everything as shown in the figure.
Connect a 40 watt incandescent lamp at the output of the
transformer. And switch ON the battery to the circuit.
The bulb will immediately come ON brightly…..your homemade 50 watt
inverrer is ready and may be used as desired by for powering many small
appliances whenever required.
