i am merley going to test it on a light bulb. i i just want to make sure it works, once that is done i can modify the circuit and then build something more robust so that it could be added to an already constructed solar panel.

 

An incandescent light bulb is a difficult load because its current is about 10 times higher when it is cool which might blow up the inverter.

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Uncle $crooge

 

ok/...... i started over circuit construction and this so far is the output from the lm358 op amp at both outputs 1 and 7. it give a square wave but the peak to peak voltage is about 13V. attached is a photo..........

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do you have any suggestion for a light load? i just want to show that it works. also what do you think about the output on the op amp and astable vibrator.

 

the circuit once again is complete but the desired output still cannot be obtained. for some reason, i i basically get the same output 12v approx. across the transformer output. which means in the end there is not boosting on the transformers behalf.

 

The max base-emitter voltage of the driver transistor is 0.65V without a load on the project and 0.8V with a 100W load.

the max base-emitter voltage of the output transistor is 0.7V without a load and 1V with a 100w load.

The two voltages are in series so the outputs of the LM358 are limited to 1.35V to 1.8V.
If the transistors are good and are connected properly then 13V at the output of the opamps is impossible.
You must have the wrong transistors or have their pins connected wrong.

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Uncle $crooge

 

for the transistors i am using the exact same transistors an in the schematic

2n3055
2sc1061 i also have tip31
lm358n
tell me what you thiink about these chips and transistors.

 

In the year 2009 are you still using darlington connected BJTs for switching high power? The Vcesat of up to 2 volts is a terrible waste of precious 12V energy. The 2N3055 runs out of useable β at a collector current of only 10A.

You can replace each darlington (e.g. Q1, Q11, R4, D1) with a high current MOSFET with no other design changes. If you cannot afford a low Rdson MOSFET then put as many as necessary in parallel to give a value of 0.01 ohms or less. You can use 6 per side BUZ0105 for us$0.55 each at N-CHANNEL MOSFET, 55V 22A .06OHM | AllElectronics.com.) Or a single POWER MOSFET MTP75N03HDL | AllElectronics.com for each side for us$1.75.

At 30A, 50% duty cycle, the power wasted in 0.01 ohms is 4.5 watts each so you only need a small heat sink.

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de KI6RWX

 

The circuit using old transistors connected as darlingtons was designed in a 3rd-world country for use in the 3rd-world country where power Mosfets are not available.

The poor people use inverters because they do not have electricity. A guy on a motorcycle picks-up discharged batteries and replaces them with charged batteries.

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Uncle $crooge

 

So all you guys agreee that if i change the design from darlington to sue of a single mosfet i will get the expected result. without having to change the controller circuit and the LM358 opamp???? and would the the output of the opamp just go directly to the mosfet with its output going directly to the transformer. i kam not really concerned about cost at this point. i was just concerned with a working model; modifications could be done afterward as it pertains to power consumption and things of that sort.

 

You may still have connection problems if you get no output; the 2N3055 should work well enough to show the concept. You can finish making sure the connections are right using the 2N3055.

Even if MOSFETs are cheap it still would be a shame to blow them up. You can make the switch at any time.

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de KI6RWX

 

A single Mosfet will not make a working high power inverter.
You need two Mosfets to drive the center-tapped transformer.

You are modifying an extremely simple inverter circuit that does not turn off if it is overloaded (instead it blow up) and does not have voltage regulation so its output voltage is too high if the load is light or if the battery is recently charged and the output voltage is too low if the load current is high or if the battery is running down.

The inverter has an extremely simple square-wave output instead of a modified one or a sine-wave one. It can drive an incandescent light bulb or a heater.

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Uncle $crooge

 

Hi guys,

sorry iwas actually referring to adding one mosfet on either leg. that is what i was trying to get. it makes it really simple if that is the case.

 

guys i was able to make a little progress. i couldnt get a battery with a rating of 10 amp so i pulled out a power supply from a computer with a current rating of 12V and 8.5 amps which is a little less than required. the output on the transformer now is a pulse at the 100 volt mark there about. is it because the currrent is not sufficient. or what do you guys think the problem is?

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Is your transformer designed for 60 Hz?

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de KI6RWX