inverter anyone know how to build one

[duffy]

Yes, you should see the 20khz on pis 11 and 14 - and also on 5 and 6. These are the RT and CT lines that run the oscillator. Pin 5 should show you a sawtooth wave.

The +150V should pop up almost immediately. The chip shouldn't blow if the fets are disconnected...

Put two .1uf caps on the +12V lines on pins 13 and 12, as near to the chip as you can get. In the past I have had problems with harmonics and high frequency mosfet coil drivers. You would think the 10μf cap would take care of it, but they are surprisingly unresponsive to high frequency harmonics (like 1mHz or more) and I can tell you from first-hand experience this particular problem will blow drivers and fets.

You are using a sensible approach to build it in stages and debug each stage, and to try operating it without the feedback connected to see if that's an issue. You could also disconnect that /Shutdown line during debugging to see if that's causing the problem.

 

[RoboWanabe]

Dumb question but what is an inverter please? is it to do with transformers like changeing the input signal to a speified signal?

 

[ericgibbs]

Dumb question but what is an inverter please? is it to do with transformers like changeing the input signal to a speified signal?

hi,
Look here, this explains.
**broken link removed**

 

[unclejed613]

an inverter is, to put it simply, a device that takes a low voltage DC input (like 12V from a car battery) and converts it to a high voltage AC output (like 120 or 240Vac) to run AC powered equipment. an inverter can also be a device that takes a low voltage DC input and converts it to a high frequency AC high voltage output (such as 600V@20khz) to operate devices like fluorescent tubes in the backlight of an LCD TV.

 

[RoboWanabe]

Thank you so much

 

[lillian]

thank you Duffy I really appreciate your support. I will do as you say with the caps because this might be a problem here. If I am not using the shutdown line should I connect pin 10 to ground

 

[duffy]

If I am not using the shutdown line should I connect pin 10 to ground

The test circuit diagram on page 5 shows it left floating when the switch isn't active, but connecting it to ground is safer than leaving it open according to page 7 of the SG3525 spec sheet -
https://www.electro-tech-online.com/custompdfs/2012/06/CD00000958.pdf

 

[unclejed613]

there was also a time when an inverter was also an electromechanical device with a motor sharing a common shaft with a generator (for high voltage DC output) or an alternator (for AC output). the other names for these inverters were "denemotor", "motor-generator" (abbreviated MG in schematics), or "rotary inverter". such devices are still in use for very large applications. a few years back i worked for an AM radio station, and their transmitter was located in an area where 3-phase AC power was not available. there was a large (about 6ft long, and 3ft diameter) rotary inverter to convert single-phase AC to 3-phase for the transmitter. so the term "inverter" actually covers a wide range of devices. so the term broadly means "a device for converting a convenient simple source of power into a needed and normally unavailable source of power" in the early days of radio, it was common to use a huge rotary inverter to convert 110VDC to the 20-30khz RF power feeding almost directly into the antenna. these devices were called Alexanderson Alternators.

 

[audioguru]

Dumb question but what is an inverter please?

An inverter makes AC 120V or 230V electrical power from a 12VDC car battery. A car battery is not designed to provide continuous power so it will quickly be destroyed.

An inverter is used by poor people in 3rd-world countries who do not have electricity, it is used by people in countries that shut off electricity often and it is used by people who go away from civilization for camping, fishing or hunting.

I have never used and have never needed an inverter.

Some inverters can power a home TV or a home sound system, lights and maybe a heater.

 

[lillian]

Thank you Duffy I made some progress today I started to get high voltage out of the circuit but shortly after the ic just stop putting out signal. What I am going to do is rebuild this circuit on a new board I am loosing too many ics and I dont know why I put the caps accross the power line and it worked long this time but something else went wrong I will get another sg3525 and start again. In the mean time do you have any circuit that use tl494 as pwm to produce the dc to dc voltage with a feed back loop . If you have could you send a copy . Thank you. I usee another 170 from a working inverter and powered up the rest of the circuit and got ac out. I even used a low frequency transformer with about 169 v and got 122v ac. I have a tl494 now so if you send a schematic I could try and build that circuit. Thank you for your help

 

[lillian]

hello Duffy I have not given up on the circuit . I am just waiting to get some other Sg3525 before i try the circuit again so as soon as I get it I willl get back to you on the dc to dc inverter. Thank you for your support so far

 

[lillian]

hello Duffy I got the ic today and rebuilt the dc to dc inverter section I am now getting voltage out but I am still having another problem now. As long as i am getting about 80v dc out the fets are fine but as soon as I go over 100v the fets start to gradually get hot and the circuit start to draw escess amperage I have to disconnect power. The good thing is for the first time I am getting Ac out of my H bridge. Thank you. I know you can help me to get this problem sorted out . i am waiting for your reply . thank you

 

[RCinFLA]

hello Duffy I got the ic today and rebuilt the dc to dc inverter section I am now getting voltage out but I am still having another problem now. As long as i am getting about 80v dc out the fets are fine but as soon as I go over 100v the fets start to gradually get hot and the circuit start to draw escess amperage I have to disconnect power. The good thing is for the first time I am getting Ac out of my H bridge. Thank you. I know you can help me to get this problem sorted out . i am waiting for your reply . thank you

Look at the duty cycle on the power MOSFET's for the DC to DC converter. The duty cycle should be a function of load and should not get too close to 50%. If the turns ratio of the transformer cannot support the required output voltage you will approach 50% duty cycle too soon. Also ensure the snubber circuits on the MOSFET drain's are preventing overshoot that exceeds breakdown rating on the MOSFET's.

 

[lillian]

thank you for your support I will soon be getting back to you on this tonight

 

[lillian]

Hello Duffy I made a break through today to some extent but still have a problem for you to solve . I start to get my AC out of the h bridge but the 50 Hz is not stable it is running like 48 to 60 HZ and back. I dont know if it is the snubber circuit that tunes this output wave form . My output from the transformer is distorted and look like a distorted double sine wave . Please help me one more step and I think I should have a working inverter. Awaiting your reply . Thank you

 

[lillian]

Hello my friend I await your reply on the unstable frequency pronlem I am having. Thank you

 

[lillian]

hello my friend I still await your support on this trouble come inverter circuit. I now get it to produce Ac but my dc 170 v is falling off from 170 v to 144 with a load of 9 watts. I am using two pairs of irf3205 fets. Please help me here is there anything I can do with the feed back loop on the ta3525 to get this voltage stable. Thanks for yout support

 

[lillian]

I am still waiting your support

 

[Willen]

For invertor oscillator, 50Hz is critical or not?
What happens if I use 40Hz or 200Hz? Does it damage my instruements?

 

[johansen]

For invertor oscillator, 50Hz is critical or not?
What happens if I use 40Hz or 200Hz? Does it damage my instruements?

higher is certainly an option.
most o'scopes won't care if you run them all the way to 400Hz (the transformers are typically overbuilt)
but you can't go lower if you have any rotating machine loads or transformers.