shelf oscilating psu

[east electronics]

simple as that ...

just seen the revox B251 power supply unit .... i may also post a schematic

that is actually a simple oscilator and more actually the circuit that was was used as an "inverter" inside the first "economic" lamp SL 18- SL25 from philips ( if memory serves properly )

only adopted to higher power ..

any comments about this circuit ? it doesnt feature none of super functions like PWM or PFC but still worked quiet well ...for long time ..

Question is asked since "we" normally power amplifiers ... not spaceships

 

[east electronics]

or it could be the other way arround

what could possibly go wrong when a circuit like that is used next to a high tech supply ?

i see no regulation and that i can live with .... anything else ???

 

[luka]

If the oscilator part is not to complex to make, I don't see nothing too bad about it. So what if it doesn't have regulation, really depends on application you need it for... But this days, IC are so cheap, I think I would still go with it, instead of only parts you see on schematic

 

[sesebe]

If I'm right this power supply have some advantage. It is a resonant one, ZVS type, the current is sinusoidal and the harmonics are very low, so less noise to the amplifier.
A SMPS with IC need to be a resonant one to have the same shape of current and is not so easy to made.

 

[east electronics]

i have seen this type of psu made before but failed all the time i think poor choise of transistors or make of transformer ... but since im going to repair the revox i might take alook to see if its possible to get some expirience from that .

i will post my results here ...

regards sakis

 

[sesebe]

Hello,

Any news with this power supply?

 

[ontoaba]

Hi, sakis.
For high power use, that self oscillating will need much bigger transistors to make it not breaking down at repetitive starting operating mechanism. While controlled switching PSU need much smaller switching transistors.
This transistor size differences will affecting many of its performance, efficiency, speed, and cost, so there are few people using that type of self oscillation in high power.

 

[Kay Pirinha]

that is actually a simple oscilator and more actually the circuit that was was used as an "inverter" inside the first "economic" lamp SL 18- SL25 from philips ( if memory serves properly )

Hi Sakis,

those pioneering Philips energy saving lamps didn't feature any electronics at all, they simply were miniaturized switch-start fluorescent lamps with in-built chokes, which made them so heavy (about 1 pound).

Modern economic lamps feature inverters comparable to your schematic.

Best regards!

 

[jitter]

Indeed, those first generation energy saving lamps had magnetic ballasts. They earned the nickname "jam jar" in Holland.

The circuitboard in the attached picture does show similarities to the left part of Sakis' schematic.

The pic, BTW, is of an end of life CFL from a well known Dutch department store, but it's acually a Philips Genie CFL.

 

[Steerpike]

Old thread, but interesting. Also interesting: Revox abandoned this switching supply and went back to a conventional one (with 4x22,000uF capacitors!) in the B251's successor, the B250.