Hi mbates14,
I can appreciate why you want to use parts on hand BUT!
The but is, you want this supply to be reliable don't you? You really must use parts that are designed for this application. Please follow some of the advice sent your way from other members.
You may have some parts already - good. Other parts are not that expensive and may be pulled from other dead equipment. You must first get a design that works well. Another point. Power transformers don't work well at frequencies away from the design frequency. In your case, 50 or 60 Hz.
I think ilimzn voiced this most directly. Relax and wait for the other forum to process your application. Listen to others who are trying to help you. None of us want to see you smoke something or hurt yourself.
I guess I'm trying to say, let us help you.
-Chris
I can appreciate why you want to use parts on hand BUT!
The but is, you want this supply to be reliable don't you? You really must use parts that are designed for this application. Please follow some of the advice sent your way from other members.
You may have some parts already - good. Other parts are not that expensive and may be pulled from other dead equipment. You must first get a design that works well. Another point. Power transformers don't work well at frequencies away from the design frequency. In your case, 50 or 60 Hz.
I think ilimzn voiced this most directly. Relax and wait for the other forum to process your application. Listen to others who are trying to help you. None of us want to see you smoke something or hurt yourself.
I guess I'm trying to say, let us help you.
-Chris
Thats my whole problem. I cant find hardly anything with SMPS other than complex math formulas that I dont even know where to begin.
Thats why I came here. Maybe you can help me.
I got this SMPS idea from another circuit that is a battery operated tube amp. Thats where I got my similar idea. and design.
Thats why I came here. Maybe you can help me.
I got this SMPS idea from another circuit that is a battery operated tube amp. Thats where I got my similar idea. and design.
I did a search up on an SG3525, cant this be used?
http://sound.westhost.com/project89.htm
I ran across that. Cant that be modified to work?
http://sound.westhost.com/project89.htm
I ran across that. Cant that be modified to work?
Matter of fact, that old 150w power inverter is designed like this:
There is a main b+ supply, about 150vdc. then there is an H-bridge switcher that switches the 150vdc at 60hz through the load.
Well, the 150vdc which is powered by the SG3525 still works. I still get 150vdc, but the H-bridge section is fried.
I might be able to just build off of the secondaries of that.
Maybe a voltage doubler? because I know itll handle it. its a 150w supply.
There is a main b+ supply, about 150vdc. then there is an H-bridge switcher that switches the 150vdc at 60hz through the load.
Well, the 150vdc which is powered by the SG3525 still works. I still get 150vdc, but the H-bridge section is fried.
I might be able to just build off of the secondaries of that.
Maybe a voltage doubler? because I know itll handle it. its a 150w supply.
If the 150 volt section is working, you should be able to rewire the the rectifier circuit to be a voltage doubler. You will need to use diodes that were made for high frequency use. A 1N4007 will literally melt in this circuit. If the inverter originally used a bridge rectifier, use two of the diodes to make a voltage doubler. The SG3525 is a universal SMPS controller chip. It has been around for at least 15 years. It could be used to make the circuit that you need, but If you already have a working inverter, see if you can modify its rectifier circuit, although you might not need to.
Most SMPS circuits use feedback from the secondary side of the transformer to adjust the duty cycle and provide regulation. Since you are using far less than the 150 watts, the switching inverter may be able to produce enough voltage under light load. You need to find the feedback loop and adjust the resistor values to find out. If you do this make sure that the capacitors can handle the increase in voltage. They will probably need replacing too.
You will need to modify the feedback loop even if you use a voltage doubler because it will always try to keep the output voltage at 150 volts.
Another possible alternative would be to leave the inverter circuit alone (its feedback circuit intact) and use a step up transformer to generate 300 volts AC then rectify it. You will need a transformer with a 110 volt and a 220 volt winding. A toroid would be best but most conventional transformers will work. To do this connect the 110 volt winding of a transformer directly in parallel with the secondary of the existing inverter transformer. Then connect a the 220 volt winding of this transformer to a rectifier circuit and filter cap. A fast diode must be used. This approach would have the worst regulation but should work for your purpose.
The TL494 is very similar to the SG3525, and may be interchangable with it in some circuits.
There are some battery powered tube amplifier designs on Steve Bench's web site:
http://members.aol.com/sbench101/
Most SMPS circuits use feedback from the secondary side of the transformer to adjust the duty cycle and provide regulation. Since you are using far less than the 150 watts, the switching inverter may be able to produce enough voltage under light load. You need to find the feedback loop and adjust the resistor values to find out. If you do this make sure that the capacitors can handle the increase in voltage. They will probably need replacing too.
You will need to modify the feedback loop even if you use a voltage doubler because it will always try to keep the output voltage at 150 volts.
Another possible alternative would be to leave the inverter circuit alone (its feedback circuit intact) and use a step up transformer to generate 300 volts AC then rectify it. You will need a transformer with a 110 volt and a 220 volt winding. A toroid would be best but most conventional transformers will work. To do this connect the 110 volt winding of a transformer directly in parallel with the secondary of the existing inverter transformer. Then connect a the 220 volt winding of this transformer to a rectifier circuit and filter cap. A fast diode must be used. This approach would have the worst regulation but should work for your purpose.
The TL494 is very similar to the SG3525, and may be interchangable with it in some circuits.
There are some battery powered tube amplifier designs on Steve Bench's web site:
http://members.aol.com/sbench101/
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