Hi Brian nice talking to you, yes like you said the relay is DC but I have rectified the output with no result, also I have made all these circuits and I got the same problem. I'm careful about the winding directions, I have made the winding of two connected primary coils in the same direction, also in the hand drawing circuits I tested all ways means that I have tested the three pins of the transistor with all three pins of transformer primary, and like I have said there's noises made by transformer it shows that oscillation is working isn't?!.Relays generally work on DC or low frequency AC. All but the multivibrator (3rd from bottom) circuits will oscillate at a frequency entirely decided by the inductance of the transformer and could be tens or thousands of KHz.
None of the circuits are particularly good or have any kind of frequency or amplitude stabilization so don't expect good or reliable results.
The transformer winding direction is vitally important. In the three lower schematics, the transformer primary is like one continuous winding in the same direction with a center tap. In the hand drawn ones if the winding feeding the base of the transistor is reversed it will not oscillate, its the direction of the winding that provides the needed phase inversion.
The 3rd from bottom has no dots to indicate connections. If you build it, be sure to connect all the junctions except the ones crossing over diagonally between transistor base pins.
Brian.
Hi Klaus, in my city there's no PCBHi,
5Mbytes of data for a couple of lines. And a lot of text but almost no information we can work on.
Thus I can just give general advice from my experience.
When I started designin electronics I soon gave up on the trial and error method. It wwas just a waste of time, a lot of smoke, damged devices and mainly disappointment.
Thus i changed my way and studied reference ciruits, learned how they are meant to work. How, why and the calculations behind it.
Also with switching power applications the PCB layout is very important. You may have absolutoey the same schematic, use the same devices but still one PCB solution may work clean, reliably, generating low heat, whil the othere does nothing useful but generating heat .. then kill itself.
Almost any semiconductor manufacturer provides very detailed documents, tutorials, examples... some even videos.
Like Brian said the shown schematics are incomplete, don´t tell the math, don´t tell what´s important about the transformer. Don´t tell about PCB...
I can only recommend to read some of them. But for sure you are free to go your own. way.
Klaus
Hi Klaus,Hi,
5Mbytes of data for a couple of lines. And a lot of text but almost no information we can work on.
Thus I can just give general advice from my experience.
When I started designin electronics I soon gave up on the trial and error method. It wwas just a waste of time, a lot of smoke, damged devices and mainly disappointment.
Thus i changed my way and studied reference ciruits, learned how they are meant to work. How, why and the calculations behind it.
Also with switching power applications the PCB layout is very important. You may have absolutoey the same schematic, use the same devices but still one PCB solution may work clean, reliably, generating low heat, whil the othere does nothing useful but generating heat .. then kill itself.
Almost any semiconductor manufacturer provides very detailed documents, tutorials, examples... some even videos.
Like Brian said the shown schematics are incomplete, don´t tell the math, don´t tell what´s important about the transformer. Don´t tell about PCB...
I can only recommend to read some of them. But for sure you are free to go your own. way.
Klaus
Hi, thanks for your reply.I attempted to build my own power inverter using a transformer in reverse. It was a center-tap type similar to your last image. I scavenged the transformer from an appliance where it powered several circuits. I thought I'd get ample 120 VAC from it.
However all I could manage was to light a 7W bulb dimly.
Each time I increased power, it generated severe spikes which fried my mosfets. I had to give up. That was many years ago when I barely knew what I was doing.
Since then I realized power transformers are designed to be at the load end of the electric company. They see the primary side wound from lots of turns of thin wire. Its Henry value is combined with an ohmic value. It only lets through a certain amount of Amperes.
By running the transformer backwards, we're asking lots of turns of thin wire to conduct in series with our load. Electron flow is hampered.
View attachment 184370
What confuses me is that there is many videos in YouTube which people makes these circuits from the beginning to the end and it seems work fine, powering up even devices of 220v from 12vdc power source!!! So I'm not sure if those videos are just a scam or I'm missing something.
(If you ask me I think those guys have lots of new batteries to put in handheld projects. I suspect their power inverter projects require that they wind many transformers, to learn the right way to make one so it carries sufficient power.)I built low-power oscillators where a transformer provides the up-and-down triggers for oscillations. (I've seen this topology called blocking oscillators.) The circuits are in the instruction manual of old-time Radio Shack electronic lab kits. I discovered component values are finicky, otherwise nothing happens.
The mystery is in the construction of inductors and transformers. It's not obvious what's wrong if the circuit does nothing.
Supply voltage is also finicky. I applied variable voltages from my power supply. Often there was a point when I turned up voltage where oscillations stopped. It's successful only within a certain range of voltage.
It's not obvious what's wrong when the circuit does nothing. Do I need to change a resistor value? The transformer ratio? Primary inductance?
When an experimenter puts up a Youtube video, he probably had to troubleshoot many problems, until his project worked. He only needs to film the steps that worked.That's when it looks easy.
If you ask me I think those guys have lots of new batteries to put in handheld projects. I suspect their power inverter projects require that they wind many transformers, to learn the right way to make one so it carries sufficient power.
The phasing I have made is the same in the last picture where there is dots, the dots in my transformer is the beginning of the winding.In the 1st ckts above - there is no reference to phasing - this could be your big issue
yes I'm using iron core transformer and for the rectifier I'm using those big rectifiers with 4 pins.Adding to Brad's words, many videos on You Tube are complete fakes. They may look real but often have hidden wiring or use light bulb loads that look to be mains powered but have flashlight bulbs inside them.
Incidentally, if your oscillations are higher than about 1KHz a normal rectifier diode will not work so measuring the recovered DC will give a wrong reading. You should drop the frequency if using an iron cored transformer or use a fast recovery diode for higher frequencies.
Brian.
Yes I agree, I'm aware about the phasing, the video below of one of transformers I have made.Only one picture shows actual dots ( phasing ) adjacent to the windings - I greatly fear your implementation misses this important point - there are no phasing marks ( dots ) on the very first images you show in post #1, if you don't get the phasing correct - the thing will never work.
So, I was wrong about those rectifiers I mentioned, I have fast recovery diodes I will used them.The bigger bridge rectifiers like you describe are no good above about 1KHz, in fact they appear as a load on the transformer but produce low DC output.
For the sake of a few components it is far safer to make an oscillator at a known frequency (50Hz or 60Hz) then use its output to drive a transformer. It avoids all the frequency problems and also offers the possibility of adding dead time to the waveform driving the transformer. Dead time in this context is a short delay between switching one driver transistor off and the other one on. It avoids a potential problem that happens if both driver transistors are partially conducting at the same time, one in the turning off phase and the other turning on. If they both conduct at the same time they short out the primary and absorb the power the other transistor is pushing to the transformer.
Brian.
Hi Brian, finally, this is the first time I got real power from this inverter the (video/picture below), like I have said, a while ago I have tried many, many times to make these circuits work, I tried everything but the problem was that the meter shows voltage even high voltage in the output but it can't power up even a 12v load which means I didn't get even the input voltage.The bigger bridge rectifiers like you describe are no good above about 1KHz, in fact they appear as a load on the transformer but produce low DC output.
For the sake of a few components it is far safer to make an oscillator at a known frequency (50Hz or 60Hz) then use its output to drive a transformer. It avoids all the frequency problems and also offers the possibility of adding dead time to the waveform driving the transformer. Dead time in this context is a short delay between switching one driver transistor off and the other one on. It avoids a potential problem that happens if both driver transistors are partially conducting at the same time, one in the turning off phase and the other turning on. If they both conduct at the same time they short out the primary and absorb the power the other transistor is pushing to the transformer.
Brian.
thank you. You mean that I can upload only schematic of oscillation circuits and the simulator circuit tell me what is the frequency?, another question, does this website work with a smart phone?.It looks as though you found the right track by trying a more reliable setup.
My own attempt at making a power inverter had all the things to make it easy even though it wasn't successful
* I used a car battery.
* I took square waves from my waveform generator with frequency counter.
* I could see what was happening on my Tektronix oscilloscope.
It's appealing to combine oscillator in the step-up transformer. But that requires adjusting everything just right. Even in simulation it requires adjusting everything just right.
There are inexpensive projects which duplicate instruments commonly used in electronics. Here's a frequency counter made from two 4017 IC's. LED's form a tens column (left) and a ones column (right). Apply incoming pulses to the clock pin (bottom right). Every second reset all IC's with a brief signal. Although the lit led's move upward rapidly, a quick eye can recognize which ones are lit just before each reset signal. My simulation has a waveform of 30 Hz. Thus the leds indicate 30 just as reset is about to occur.
If you wish to count frequencies higher than 99, add a hundreds column by adding another 4017. Etc.
--- Updated ---
View attachment 184439
By clicking this link,
1) It opens website falstad.com/circuit
2) Loads my schematic in the simulator
3) Runs it on your computer
Yes, it seems that the circuit need more work, but I don't think that they sell 555 timer here in my city, unless if I use some old similar IC taken from old devices's boards I have, I have many of them I believe that some of them are similar to 555 timer such those in companies made smps, maybe.Well done for getting it work so far.
You still really need a fixed oscillator to make sure the transformer can work efficiently. I would suggest using a 555 timer with a variable resistor to set the frequency. 555s should be able to provide enough base current to drive one of the transistors, the other will then follow. Ideally you drive both transistors, it will give better symmetry to the waveform.
Consider that if you try to run the output into something frequency sensitive, like an other transformer or a motor, any deviation from their designed frequency will result in less power or in the case of a motor, it might run at the wrong speed.
Brian.
Yes, I saw it run on my iPhone. Everything is tiny of course. My fingertips are awkward as I try to tap where I want.thank you. You mean that I can upload only schematic of oscillation circuits and the simulator circuit tell me what is the frequency?, another question, does this website work with a smart phone?.
OK, thanks, I will try it later when I work on oscillator.Yes, I saw it run on my iPhone. Everything is tiny of course. My fingertips are awkward as I try to tap where I want.
Command scope traces by tapping on a component and choosing New Scope trace. Scope traces travel across the screen. Frequencies, duty cycles, appear after a few cycles. By tapping on a scope trace it opens options for you to choose.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?