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 12/120V inverter again
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tim
Mad Scientist

198 Posts

Posted - Oct 08 2006 :  12:11:48 PM  Show Profile  Reply with Quote
well to make an inverter but to put out 24v ac , maybe you can try a throwaway camera flash circuit and take away the diode then becomes ac but use resistors to bring down the voltage.
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Benito
Apprentece

5 Posts

Posted - Oct 09 2006 :  1:15:37 PM  Show Profile  Reply with Quote
Audioguru, did you get to see the schematic Maloy was descibing?
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Oct 09 2006 :  1:54:25 PM  Show Profile  Reply with Quote
quote:
Originally posted by Benito

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


Who is Maloy?
Which schematic of what?
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Benito
Apprentece

5 Posts

Posted - Oct 12 2006 :  05:35:17 AM  Show Profile  Reply with Quote
quote:
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.


I am referring to this Maloy...
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Oct 12 2006 :  6:33:04 PM  Show Profile  Reply with Quote
Benito,
This inverter circuit doesn't work. Its capacitors are backwards and the transistors' emitter-base junctions have avalanche breakdown like a zener diode, causing extremely high current to be wasted in the capacitors and transistors. The base current for the transistors is too low and more powerful transistors or a more powerful transformer won't make any difference.

I linked to a 500W inverter that uses 8 2N3055 output transistors, 2 2N3055 driver transistors, 2 medium power pre-driver transistors, a dual opamp and a Cmos oscillator and it works well. The link is gone now and I can't attach it from my hard drive to here.
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tim
Mad Scientist

198 Posts

Posted - Oct 17 2006 :  6:13:28 PM  Show Profile  Reply with Quote
ok, forget it guys i spent almost 2 years trying to get that very inverter circuit to work. well i did how many caps later and how many transistors but never the way i thought it would work. rewinding transformers the works so i finally put it to rest and if you guys dont do the same you might need a head shrink. all i was ever able to get that inverter to power was a 19 inch color tv for a minute and a half .
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shivick21
Apprentice

Philippines
57 Posts

Posted - Oct 24 2006 :  03:38:54 AM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
is it posible to use our old PSU transformer that uses switching tech on this Inverter? well PSU converts sine wave to square wave before it fed itself to the transformer... instead of 60 hz of 220/110 volts... it regulates its cycles on the demand of watts that needed for the pc.. if you seen china's schematic or their inverter products. the have the max rating of 600-800 watts w/ minimal power loss coz of this. and it will also decrease its size, weight and even its product parts cost. IMO. well im having a problem building audioguru's mod's shematic inverter but i got it worked. im not satisfied on its result. due to my small transfromer (1A) and only 6 2n3055.. i get a buzzing sound and i need to turn on/off for the buzz to wear off(this is my starter projects). and im still having a problem on its ic.. CD4047 .at first test.. it went ok.. after some trial and error... my ic CD4047 generates adnormal heat and my inverter dont work. i try replacing it with MN4047 (w/c they say its similar) and end up working again.. but... i take off the LM358 in the schematic and redirect the impluse to the 2SC1061. i got it work again. i but still... there are not much force to light an CFL.

nothing anusual..
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Binary 1011001101
Nobel Prize Winner

United Kingdom
569 Posts

Posted - Oct 24 2006 :  04:36:53 AM  Show Profile  Reply with Quote
I take it that makeing yourself a inverter isnt so simple. I found a really cheap inverter but it ran on 24V, is there a way to get 12V up to 24V at quite a high amperage 5A?
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Oct 24 2006 :  09:31:34 AM  Show Profile  Reply with Quote
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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shivick21
Apprentice

Philippines
57 Posts

Posted - Oct 24 2006 :  1:01:36 PM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
quote:
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.


well i just use these as my test purposes.. btw.... i about C1 (.1uF metalized caps) is there any subsitute for these? and, can i use MN4047 rather CD4047? an do i realy need ML358 for amp? coz when i place IC2 in place.. i only got half of the transformer running..

nothing anusual..
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Oct 24 2006 :  4:25:57 PM  Show Profile  Reply with Quote
A metalized film capacitor is mylar or polyester. In the Orient they are called "green caps" and 0.1uF/5% is marked "104J". I use Philips or Siemens and they are marked "100nFJ".
I think an MN4047 is made by Panasonic but I have never seen one. All American and European semiconductor manufacturers make a CD4047.
The LM358 dual opamp boosts the the two outputs of the CD4047 from its 8mA to about 20mA so the transistors have enough input current.
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shivick21
Apprentice

Philippines
57 Posts

Posted - Oct 26 2006 :  07:55:49 AM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
ei! i got my inverter working again! yey! but i have some problems with it. it seems that when i disconect one of the signal pulse from LM358 to C/H1061, i get 190 volts w/o load and 80 volts with a 10w bulb or when i disconect one line from the transformer, i get this results too. but if i connect both signal/line form transformer, the inverter doesent work... ill post some pics on my inverter.. btw. does c1 need to be polarized? coz. it sayz on its diagram that it is polarized. but mylar/polyester ones are not.

nothing anusual..
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Oct 26 2006 :  8:53:33 PM  Show Profile  Reply with Quote
Shivick,
Instead of a center-tapped 24V transformer winding (12V-0V-12V), your transformer might have two 12V windings. They must be wired with the correct phasing to work properly in the inverter circuit.
C1 must not be polarized.
The inverter's output is a square-wave that is measured incorrectly with an ordinary voltmeter that is made to measure sine-waves.
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shivick21
Apprentice

Philippines
57 Posts

Posted - Nov 04 2006 :  02:40:42 AM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
audioguru,
It seems that the controller itself draws a large amount of current just to feed on the C1061.. i remove the controller and try to figure out how to mimic it.... when i touch the collector terminal of c1061, the transformer generets a humming sound... and the bulb starts to glow. i measured the amount of energy that its produce and end up 170V. now... when i accidentally touched the emmitter junction of the other C1061... the noise starts humm smothly and the voltage reach @ 190V.. on one side only... i try hook up some series of resistors and it generate 170v with the annoying humm sound..

my question is.. what signal do the c1061 need to trigger its pulse?

nothing anusual..
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yomi
New Member

Nigeria
2 Posts

Posted - Nov 04 2006 :  2:06:11 PM  Show Profile  Reply with Quote
using 4047 with darliton pair in oslator circuit
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