PSU Design of Chevin...

[HaaiFaai]

Hello,

Does anyone here uses the very simple PSU design of Chevin
(modified lamp balast switching psu)in their projects?
I saw the schematics, and it's really truly simple using Mosfets and a Ferroxcube transformer in a simple self oscillation mode.
No IC's, just a small bank of mosfets, used in a modified lamp ballast application.
(And they ask a lot for it..:-))



[Edited by HaaiFaai on 11-22-2001 at 08:07 AM]

[blmn]

HaaiFaai,

I'm interested on this circuit. I'm thinking about a variaton over simple self oscillating circuits to feed power amps. Where could I find it?

Tks in advance

[HaaiFaai]

Hello,

It is in original a design I saw at the application books of Motorola and International Rectifiers.
I can recommend you the Power Applications Manual DL410/D REV1 from Motorola.This is real a great book, not only you can find there lineair, also switching and even a class D amplifier.
If you want to know where the Leach amplifier is based on, just browse in this book.

[HaaiFaai]

BTW: the supply consists of (one for each channel)

1 ETD 49 Ferroxcube bobine (Philips)
12 times IRF 740 mosfet (hexfet) International Rectifier
small ferrit signal transformer 3C85
Capacitorbank approx. 10000-15000 Uf/450 volts
High speed rectifier diodes
Inrush current limiter
Those are the big parts, not so expensive and definitive lighter then any normal transformer, anyway they use it for their professional amplifiers rated 600-1000 Watt pro channel..
(I can specify details if needed)

[blmn]

Tks a lot.!!!

[Loner]

Hi.
I have some schematics of these amps. The power supply uses some IRF740 Fets (6 or 12 depending on model) and an output transformer (ETD49 core) with 3 secondary terminals(+V, -V and a central terminal). But the only thing I do not understand is why they connect this central terminal to the + terminal of loudspeaker instead of the ground point of the amp output stage.¿Can someone explain the reason of this?

[GeneralKang]

Hey loner how can I get those schematics form you?


Thanks

[HaaiFaai]

The design Chevin uses is a patent from Hafler audio and can be viewed on their website,its the so called grounded
emitter design(with bipolair transistors)
For details on the psu I can scan some articles if you want.
The original design is a modified lamp ballast schematics with no IC's, just a self oscillating mosfet set up.
The trick is done in the ETD 49 transformer which has a small airflow channel to get more output while maintaining
good power characteristics.
The psu is real simple and light weighted.
Btw the advantage of the grounded emitter design is a very simple low voltage driver because the needed voltage swing is done by the output stage itself.
Chevin uses mosfets instead of bipolair in their output stage (I think they are using lateral ones)

[Edited by HaaiFaai on 12-09-2001 at 09:43 AM]

[GeneralKang]

Thanks for the info, please send me those articles by email.

[AudioFreak]

I've never much liked switching supplies for audio gear outside of car/boat etc. environment because even if the supply is nice and clean the high speed rectification inevitably radiates significant amounts of rf noise.