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Originally posted by Benito

Audioguru, did you get to see the schematic Maloy was descibing?

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Originally posted by maloy

Hi guys, today I'll try to explain how to do it working.First of all : I am not an electronic engineer but a mechanic so I vill explain everything from mechanical point of view. At the beginning , when I started to build inverter I tried to follow instractions and finished with exploded capacitors . After several attempts and losing my money again and again I started to think that there something wrong. Thus surcuit itself is not bad or wrong , what was wrong? From technical point of view the transistors are not synchronized and practically we have some sort of backwave that mean that circuit conduct current back through capacitors to transistors, so simply there is no longer direct current but some sort of alternative current ,thus my solution is cheapest bipolar capacitors, in my case:47uf 50v electrolite caps,they work great never getting hot. Next point : do not use expensive power transistors , they are good but if you get them overloaded the next thing they could be used for is to be thrown away thus they are not so durable. What can I say about their cheap brothers (2sd850 , 2n3055) you can overload them for a short time without problems bbut do not forget about appropriate colling . the schematic is not so powerful as stated but said that could be designed for greater output . In the state the schematic presented it can produce no more than 35-40w at 120v and not capable to initiate transformers ratios designed for 240v, the usage of more powerful transistors can solve that problem but they simply getting overloaded, why? because physical thickness of conductor is not thick enough; we drain huge amounts of current through curcuit and if you remember that to rotae dc motor rated at 1hp at full load we need condactor wire no less than 3mm in diameter , so what the thickness of the transistors legs? Solution is use as many as you can instale , connect them in paralel (I use 4 of 2n 3055 2on each side) so they act as one big super transistor and their combained thickness is powerfull enough to connect any load you like. Transistors mast be connected to each other with reasonably thick wire . The rest of curcuit could be connected ordinary as you like, my transformer is was taken from video recorder power supply,its dimensions;5x5x6cm. This transformer has been rewind , I used wire from microwave transformer for centertaped winding I used thick wire and for output winding the thin wire.So if you did not anderstand something just ask me and I'll try to enplane everything, other way the system should work without any major adjustment.

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Shivick,
A 1A transformer is much too small for an inverter. The square-wave inverter' circuit needs maybe 20W to begin working but your transformer supplies only 12W. The smallest transforer is about 10A for an output of 100W.

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