How to make dc to ac converter more efficient?

[sebswed]

Hi all.

I completed a circuit I found here https://howtodosteps.blogspot.se/2016/08/simple-4-volt-dc-to-400-volt-ac-output.html but the uncooled transistor gets around 49*C (120*F) with no load attached. I'm not an expert in any way but this seems to indicate to me that it is converting energy into heat, reducing its efficiency. Did I understand that correctly? Other than that I am very happy with the circuit. The video shows a 240R resistor but the schematics show a 1.5K, not sure why.

I read on Google that the max temp for the TIP41C should not exceed 25*C (77*F) I'm not sure if there is a certain strain on the transistor reducing it's lifespan when I cool it down with a cooling element.

Is there a way for me to make this circuit more efficient?

Thanks in advance and kind regards,
Sebastiaan

 

[Harald Kapp]

the uncooled transistor gets around 49*C

Sounds cool whith respect to power transistors.

I read on Google that the max temp for the TIP41C should not exceed 25*C

Where? I'd be interested to see this.
It is nonsense. You'd never be able to use this transistor in an environment 'hotter' than 25 °C. I'm quite sure you misinterpreted some information. For example it is common to list operating parameters in a tabular form for an environmental temperatire of 25 °C and to add parameters (typically charts) that show the degradation with rising (or falling) temperature.

Is there a way for me to make this circuit more efficient?

This circuit can probably be improved, but not much. There are other circuit topologies for efficient converters. These rely on controller ics and some peripheral circuitry.
A very important factor in improving efficiency is a well designed transformer that matches the requirements (voltages, currents) as well as possible.
For your simple setup it is probably best to simply add a big heatsink to the transistor.

Warning: you're dealing with dangerous voltage here. Observe all necessary precautions. Ask an experienced person to supervise the safety of your setup.
Neither I personally nor any other person on this forum shall be made responsible in case of an accident due to non-observance of the relevant safety measures.

 

[sebswed]

Thanks Harald. Yes it turned out I misinterpreted the text about 25*C, it was about the characteristics at 25*C.

Thanks again for your answers!