| T O P I C R E V I E W |
| YS |
Posted - Mar 05 2004 : 10:13:25 PM
Very popular topic.. Looks like people have problems with this device.
I was wondering about this schematic. Just a mental exercise, you know. What caught my attention is the fact that both tantalum caps showed in - as I think - reversed polarity.
Look at the schematics: the base of the transistor never gets more than 1V above emitter voltage - when the transistor is opened; when the transistor is closed, the base voltage may go well below 0.
The other side of the cap is connected to collector. When transistor opened, it goes to almost 0; but when it is closed, it goes well above 12V (without a diode; 13V with a diode in place).
Therefore, I would connect minus of the caps to bases and plus to collectors. BTW, blowing caps may be just a sequence of wrong polarity..
So, my advice would be - change caps polarity.
Opinions are welcome.
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| 15 L A T E S T R E P L I E S (Newest First) |
| audioguru |
Posted - Apr 25 2013 : 2:25:14 PM
This project works very poorly. The transistors have avalanche breakdown and waste most of the low output power.
A mains transformer is designed to operate at 50Hz or 60Hz and might work poorly at 400Hz. |
| hsh_4321 |
Posted - Apr 24 2013 : 07:36:51 AM
I'm trying this inverter in proteus simulation
I wanted to know does it work properly with high frequncies too? I want a frequency between 200 to 400 Hz
when I calculate the R and C for 200 and something Hz It kinda works with 18k ohm and 22uF but when I connect the transformer (P:834 ohm,5.4H and S:9 ohm , 0.8mH)the voltage becomes almost zero
is there any calculation that includes all the measures?!
tired of trial and error!!!! |
| audioguru |
Posted - Sep 03 2012 : 12:45:50 PM
Hi Rhonn,
I still have some new CD4017 ICs in DIP and surface-mount packages.
I would send you a few but you are too far away on the other side of the world.
Come here to get them.
I still have never needed and have never used an inverter. |
| kasamiko |
Posted - Sep 02 2012 : 08:05:21 AM
I'm back! and to my surprised this inverter topics never ends..:P
The inverter I made about 8 yrs ago suddenly stop working...upon circuit tracing, i found out that CD4047 is fried..:( don't know what's the reason but my suspect is voltage spike since I never put any zener/decoupling caps on IC Vcc line...
The sad part is it's not available anymore in my place, have to order it online cost about 3.5 US$ in bag of 5.
I got this PWM inverter using SG3524 with feedback using photo-coupler..Got all the stuff and will assemble and assessed its performance later..
BR
rhonn
`
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| audioguru |
Posted - Jun 26 2012 : 08:50:33 AM
If the transformer is not designed properly then it is probably saturating.
Try the circuit with a 24V center-tapped to 120V power transformer made by a power transformer manufacturer rated for 100W to 300W. |
| seb27 |
Posted - Jun 19 2012 : 10:09:27 AM
Hello,
I made the circuit for testing, exactly as described, I just used my home made center tapped tranformer (in order to get an ouput of 12VAC)
It works (I mean I get well 12VAC output) but @ 3000HZ!! and the circuit consumes 3.5A without load , very strange isn'it!?
Did you have an idea of what I could doing wrong?
Thanks |
| pebe |
Posted - Apr 27 2012 : 10:36:46 PM
Why use tantalum caps? Electrolytics with a 50V working voltage would do as long as they are fitted with the correct polarity - positive to collector.
But like I said - that's not the problem. Ths bases need to be proteced with diodes. The circuit using 2N3055s is rubbish! |
| guruji |
Posted - Apr 27 2012 : 4:16:07 PM
Then what one should use instead of those tantalium caps? cause these are not easy to find |
| pebe |
Posted - Apr 27 2012 : 08:07:51 AM
Putting two caps in series will double the voltage rating, but that is not the problem.
When the multivibrator flips state, the collector voltage of the ON transistor will drop by about 25V. That voltage is transferred to the base of the other transistor, trying to take the base voltage down to about –24.5V. As that is more than the –6V maximum negative voltage of most transistors then the BE junction will zener and the transistor will probably fail.
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| guruji |
Posted - Apr 26 2012 : 4:39:12 PM
Hi Aaron thanks for sharing this inverter schematic. Regarding those caps is ok to do two 220uf electrolyte in series on both sides as a guy said?
Thanks
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| Aaron Cake |
Posted - Mar 17 2012 : 10:40:49 AM
quote:
Originally posted by harry504
I have very little time, and searching 61 pages for that and selecting which circuit is tested will take more time, that's why i need only one tested and working 500w 12V/220V Inverter circuit.
I was not aware that our time was so much less valuable than yours.
But it's not about working harder, it's about working smarter.
For example, select "Printer Friendly" when you view the topic, do a CTRL-F, and search the entire thread for "500W".
Or use Google to search the thread.
A 500W inverter is about $20 at most discount stores, so that would save you even more time. |
| audioguru |
Posted - Mar 13 2012 : 4:47:53 PM
The 500W inverter that I helped fix on another website has a squarewave output so it cannot power many electronic or motorized speed controlled products. It does not have voltage regulation so its voltage is too high when the battery is charged and/or the load current is low. The voltage is too low as the battery voltage runs down and/or the load current is high. It does not stop to prevent discharging a battery too low.
It uses obsolete parts that are available in a 3rd-world country.
It is used in a 3rd-world country where people do not have electricity. A discharged battery is picked up and a charged one replaces it. |
| harry504 |
Posted - Mar 11 2012 : 06:49:16 AM
I have very little time, and searching 61 pages for that and selecting which circuit is tested will take more time, that's why i need only one tested and working 500w 12V/220V Inverter circuit. |
| Aaron Cake |
Posted - Mar 10 2012 : 10:18:24 AM
quote:
Originally posted by harry504
Hi,
I want to ask Mr. audio guru to please upload a tested circuit diagram of 500W inverter. I am using 12V/120A of Lead acid battery and I want to power the Fans & lights which operates at 220V.
There are multiple such circuits already posted in this thread. Just work back from the last post through the pages. |
| harry504 |
Posted - Mar 10 2012 : 03:42:41 AM
Hi,
I want to ask Mr. audio guru to please upload a tested circuit diagram of 500W inverter. I am using 12V/120A of Lead acid battery and I want to power the Fans & lights which operates at 220V. |
