Hi,
Just a idea thrown, probably stupid, but don't know, and want to ask if it would work :
Let say, i want 250-300VDC for tube amp.
Can i do a "normal" smps with ir2153, with a simple atx transformer, but after this transformer, before rectifier directly add another atx transformer connecting it in reverse side so that the two transformers are connected by their "normal secondaries", and so putting rectifiers after both transformer, so connected to the normal primary of the last transformer.
So i do : AC line => switching => atx transformer => (whatever for example 50VAC high frequency) => atx transformer reversed => 300VAC high frequency=>rectifiers.
Would it work ???? It seems too easy !?
Just a idea thrown, probably stupid, but don't know, and want to ask if it would work :
Let say, i want 250-300VDC for tube amp.
Can i do a "normal" smps with ir2153, with a simple atx transformer, but after this transformer, before rectifier directly add another atx transformer connecting it in reverse side so that the two transformers are connected by their "normal secondaries", and so putting rectifiers after both transformer, so connected to the normal primary of the last transformer.
So i do : AC line => switching => atx transformer => (whatever for example 50VAC high frequency) => atx transformer reversed => 300VAC high frequency=>rectifiers.
Would it work ???? It seems too easy !?
It will work, but with some inconvenients: the magnetizing current will doubled, which should be of no consequence, and the internal impedance (leakage inductance + copper resistance) will also be doubled.
This will affect the regulation and the I*R losses, but everything should remain manageable.
It will also have side benefits though: the common-mode impedance caused by the parasitic capacitances will be doubled, which will reduce the level of residues injected to the secondary side
This will affect the regulation and the I*R losses, but everything should remain manageable.
It will also have side benefits though: the common-mode impedance caused by the parasitic capacitances will be doubled, which will reduce the level of residues injected to the secondary side
Yes it works, has been done so.
I even use otherwise unmodified ATX psu with additional back-to-back transformer.
One has actually 4 (four) transformers connected which provide the 4 independent power supplies (300v each w/doublers) for a little circlotrone, the 5v and 12v outputs beefed up to 6v / 15v for heaters. Regulation is on LV, HV is unregulated.
Doublers may be needed because of half bridge primary runs at 150v ac, so you normally don't get 300v back. Because atx txfms have no center tapped primary, doublers or bridge rectifiers are needed anyway, half wave would saturate the core - no air gap ...
Current project is also based on atx psu, -12v (mod)/+12v = 25v for heaters, back-to-back txfmr gives +150v/-150v thru doubler, another smaller txfmr +380v/-380v for bias and partial screen drive. Again regulation is on +12v only.
Tried to regulate the HV or mixed HV/LV but this turns out to be problematic especially with variable loads ... txfmrs buzzing, stability problems, LV sagging .... unresolved so far.
Another problem you may run into is cold heater current surge requiring NTC and inrush current of large HV caps (>47uF) requiring some current limit scheme, really slow start (several seconds) etc.....
By the way, the atx built in primary overcurrent shut-down feature proved very helpful during experiments, w/o many a flaw, oversight, slip means blown transistor switches.
I even use otherwise unmodified ATX psu with additional back-to-back transformer.
One has actually 4 (four) transformers connected which provide the 4 independent power supplies (300v each w/doublers) for a little circlotrone, the 5v and 12v outputs beefed up to 6v / 15v for heaters. Regulation is on LV, HV is unregulated.
Doublers may be needed because of half bridge primary runs at 150v ac, so you normally don't get 300v back. Because atx txfms have no center tapped primary, doublers or bridge rectifiers are needed anyway, half wave would saturate the core - no air gap ...
Current project is also based on atx psu, -12v (mod)/+12v = 25v for heaters, back-to-back txfmr gives +150v/-150v thru doubler, another smaller txfmr +380v/-380v for bias and partial screen drive. Again regulation is on +12v only.
Tried to regulate the HV or mixed HV/LV but this turns out to be problematic especially with variable loads ... txfmrs buzzing, stability problems, LV sagging .... unresolved so far.
Another problem you may run into is cold heater current surge requiring NTC and inrush current of large HV caps (>47uF) requiring some current limit scheme, really slow start (several seconds) etc.....
By the way, the atx built in primary overcurrent shut-down feature proved very helpful during experiments, w/o many a flaw, oversight, slip means blown transistor switches.
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