Inverter Circuit 12V DC to 230VAC Sine Wave
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audioguru2
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You need to study about transformers.
The size of the core is determined by the frequency and amount of magnetic flux it can have without saturating. You need a high flux to have a high power. High power also requires thick low resistance wire.
The number of turns for the primary winding determines its inductance and leakage inductance that determines how much current the inverter draws without a load.
The size of the core is determined by the frequency and amount of magnetic flux it can have without saturating. You need a high flux to have a high power. High power also requires thick low resistance wire.
The number of turns for the primary winding determines its inductance and leakage inductance that determines how much current the inverter draws without a load.
audioguru2
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Welcome back, Steven. ;D
We need to know the continuous power rating of your new inverter. Also please attach its schematic and parts list.
It looks like a two transistor multivibrator driving the output transistors. Its output is probably a square-wave.
It will be interesting to see if and how its design stops the multivibrator transistors from having avalanche breakdown.
It will also be interesting to see how the circuit deals with inductive voltage spikes since it doesn't appear to have any protection diodes.
We need to know the continuous power rating of your new inverter. Also please attach its schematic and parts list.
It looks like a two transistor multivibrator driving the output transistors. Its output is probably a square-wave.
It will be interesting to see if and how its design stops the multivibrator transistors from having avalanche breakdown.
It will also be interesting to see how the circuit deals with inductive voltage spikes since it doesn't appear to have any protection diodes.
ive allready mounted the heatsinks on the 2 transistors on the main board, just have to wire it up and add the 2 other transistors and big separate heatsinks to them and the transformer, ive typed out the instructions etc so here they are12_to_240_vac_convertor_circiut.txt
audioguru2
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Hee, hee. ;D ;D
120W input makes only 60W to 70W output. Nearly half of the input power makes heat.
No schematic?
120W input makes only 60W to 70W output. Nearly half of the input power makes heat.
No schematic?
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audioguru2
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Hi Sasi,
How are you?
What do you think about Steven's 50% efficient square-wave inverter?
What do you think about the recent "deletion and corrections" that were made to our 500W inverter project?:
http://www.electronics-lab.com/projects/power/033/index.html
How are you?
What do you think about Steven's 50% efficient square-wave inverter?
What do you think about the recent "deletion and corrections" that were made to our 500W inverter project?:
http://www.electronics-lab.com/projects/power/033/index.html
audioguru2
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Does it work? Does it get really hot?steven said:
It will be difficult to measure its square-wave output voltage accurately with a meter that doesn't measure AC with "true RMS" circuitry.
Please post its schematic so we can see "what makes it tick".
Steven,
It looks like a nice little kit. It is a shame they didn't include the transformer and heat sinks, but it looks like a nice simple kit for those who do not need a lot of power.
Where will you use it? Did you purchase the kit for a specific purpose or for learning about inverters?
MP
It looks like a nice little kit. It is a shame they didn't include the transformer and heat sinks, but it looks like a nice simple kit for those who do not need a lot of power.
Where will you use it? Did you purchase the kit for a specific purpose or for learning about inverters?
MP
hey mp i brought the invertor kit as i was ciurious as to how something so small would do what they say it dose , ive had an inverter once but it dident put out enougth current to power a drill, in fact it just barely turend it and it lite a house hold globe only dimly so i wonder what this inverter will deliver, the transformer they recamended in the catalouge i have to buy it and the 2 heatsinks sepparate , it says in the instructions that for more output power add a 2n3055 transistor in parralell with each of the other 2 but dose it really matter which ones you use in the 2n3055 range with the different manufacterers , the ones that came with the kit have tesla written on them , im gona try a normal 2n3055 and see what goes, when i get the last bits i need , even if it dont deliver the current output i need ill try then, the parralell transistor setup for more power or ill use what i got for a bingo feul reactor i plan to try makeing , and for the hydrogen from water thing
The transformer that you choose will make quite a difference as to what you get out of this device. I assume the kit gave you a recommendation. You should be sure to get one as good as the recommendation or better.
Regarding the 2N3055s, it does not matter which manufacturer as long as the transistor specs are correct.
MP
Regarding the 2N3055s, it does not matter which manufacturer as long as the transistor specs are correct.
MP
audioguru2
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Hi Guys,
I found the schematic of Steven's super-simple inverter kit and I have figured out why it wastes half of its supply power and has an output power of only 60W to 70W:
1) The BD234 PNP driver transistors are in a multivibrator like I thought. They have avalanche breakdown since their bases try to swing 12V above the supply voltage but the absolute max reverse voltage of their emitter-base junction is only 5V. This wastes a lot of power that should be used to turn on the output transistors harder.
2) The BD234 driver transistors don't have enough base current to saturate well which wastes power.
3) The 2N3055 output transistors also don't have enough base current to saturate well so they also waste power.
Paralleled pairs of output transistors would increase the output power only a little because each one receives half the base current as one. Of course the transistors must be matched when paralleled or the one with the most gain will hog the load and will fail first.
View attachment 40074
I found the schematic of Steven's super-simple inverter kit and I have figured out why it wastes half of its supply power and has an output power of only 60W to 70W:
1) The BD234 PNP driver transistors are in a multivibrator like I thought. They have avalanche breakdown since their bases try to swing 12V above the supply voltage but the absolute max reverse voltage of their emitter-base junction is only 5V. This wastes a lot of power that should be used to turn on the output transistors harder.
2) The BD234 driver transistors don't have enough base current to saturate well which wastes power.
3) The 2N3055 output transistors also don't have enough base current to saturate well so they also waste power.
Paralleled pairs of output transistors would increase the output power only a little because each one receives half the base current as one. Of course the transistors must be matched when paralleled or the one with the most gain will hog the load and will fail first.
View attachment 40074
thankyou for that diagnostic audio guru , it sounds like that kit dont deliver what the makers say it dose, 140 watts they say , well anyhow ill find a use for what i can get out of it when i get the transformer and heat sinks, the 2 transistors that originally came with it had tesla written on them, i have no info on them , and dont know how good they would really be so maybe ill try them first , and see how they go
audioguru2
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Hi Steven,steven said:
My first comment about the kit was about the first line in its instructions, "max 120 watts input, output power max. 60...70 watts". The circuit's output cannot provide anywhere near 140W. So I calculated that its input power is about 105W and its output power about 62W. Depending on the very wide gain range of its transistors it could be better or be worse. Maybe the maker tested the transistors and used only the high gain ones, or ordered high gain transistors from a manufacturer. Then it will be a little better.
It is difficult to guess how long the driver transistors and coupling capacitors will survive since the transistors are constantly having avalanche breakdown. At my first job at Philips I was told to never design a circuit that lets a transistor have avalanche breakdown. I have seen the same comment many times on the internet.
The output voltage of this inverter isn't regulated and could go up to 300V. The maker says so. They also say that its output voltage is higher in Australia. 240V/220V x 300V= 327V.
I don't see protection diodes to clamp inductive voltage spikes from the transformer or from the load.
It has a square-wave output so it will be difficult for you to measure its output voltage if you have a meter that is calibrated for sine-waves.
Please let us know if you find a good job for it to do. ;D
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