kartino,
Thanks for your encouragement and information.
Which brand of PSU you checked ?? Do the PSUs you checked have similar circuitry ??
It is not easy to find old/used PSUs in HongKOng. The new ones are quite expensive. 450W would cost 30USD. Anyway, keep trying.
My opinion is that by adjusting R25 to get right output voltage , one can get a stabilized output.
kb.
Thanks for your encouragement and information.
Which brand of PSU you checked ?? Do the PSUs you checked have similar circuitry ??
It is not easy to find old/used PSUs in HongKOng. The new ones are quite expensive. 450W would cost 30USD. Anyway, keep trying.
My opinion is that by adjusting R25 to get right output voltage , one can get a stabilized output.
kb.
Hi,
In here, the PSU ATX are have lot of brands, even they have exactly same inside. There are big computer stores in Jakarta, where local assembling for cheap PC.
Most of "Made in China" PSU ATX have similar circuit. I think so for others brand. The voltage reference taken from all 3.3V, 5.5V and 12V in parallel and one divided resistor to ground. The feeding for control circuit taken from +12V. I think for half bridge PSU ATX will have same configuration.
I am worry that for you guys, it may little bit complex, if you didn't find "Made in China" PSU. I see PSU from Taiwan still use flyback config, that not so easy for modification.
You can also make modification as your mentioned, but you still neednegative rails, since the -12V is only 0.5-1A. The others, the 3.3V and 5.5V have very big current that useless. If you only need single rail, better you use your idea, and remove all 3.3V and 5.5V parts.
BTW, Hong Kong is part of China but why you can not find PSU ATX like what I mentioned?
Regards,
Kartino
In here, the PSU ATX are have lot of brands, even they have exactly same inside. There are big computer stores in Jakarta, where local assembling for cheap PC.
Most of "Made in China" PSU ATX have similar circuit. I think so for others brand. The voltage reference taken from all 3.3V, 5.5V and 12V in parallel and one divided resistor to ground. The feeding for control circuit taken from +12V. I think for half bridge PSU ATX will have same configuration.
I am worry that for you guys, it may little bit complex, if you didn't find "Made in China" PSU. I see PSU from Taiwan still use flyback config, that not so easy for modification.
You can also make modification as your mentioned, but you still neednegative rails, since the -12V is only 0.5-1A. The others, the 3.3V and 5.5V have very big current that useless. If you only need single rail, better you use your idea, and remove all 3.3V and 5.5V parts.
BTW, Hong Kong is part of China but why you can not find PSU ATX like what I mentioned?
Regards,
Kartino
Hi,
I check again the reference voltage for the ATX PSU (mine). As I said before that the reference voltage taken from +3.3V, +5.5V and +12V with resistor for each. But after I remove the +5.5V actually the PSU did not work.
It caused by although that the resistors in parallel but actually they give not equal voltage but only from +5.5V that give the right reference. By remove the +5.5V the PSU will have overvoltage fault.
There are two alternative now:
1. Let +5.5V exist
2. Give reference from +12V with resistor divider as replace the reference from +5.5V with equal reference.
OK, now is up to your choice and your experience.
Best Regards,
Kartino
I check again the reference voltage for the ATX PSU (mine). As I said before that the reference voltage taken from +3.3V, +5.5V and +12V with resistor for each. But after I remove the +5.5V actually the PSU did not work.
It caused by although that the resistors in parallel but actually they give not equal voltage but only from +5.5V that give the right reference. By remove the +5.5V the PSU will have overvoltage fault.
There are two alternative now:
1. Let +5.5V exist
2. Give reference from +12V with resistor divider as replace the reference from +5.5V with equal reference.
OK, now is up to your choice and your experience.
Best Regards,
Kartino
recent acquisition:
An externally hosted image should be here but it was not working when we last tested it.
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