sorry for offtopic
ohh , the one quite far from the main road.anyway what is a SMD ? last time my interviewer asked me whether I have built a PSU myself.

This post has been edited by jasonkwk: Jul 11 2007, 11:21 PM

Surface Mount Device, teeny weeny discreet components that don't require through hole connections.

Haha...oicccc....but should we be calculating a retailed products like tat? wat about side cost like R&D, etc...
no offence but dun tell me u'll calculate everythin parts by parts based on ur understanding b4 doing d purchase...

e.g. buy car: windshield $x, paint (per sq m) $x, rubbers (per kg) $x, steel (per kg) $x, etc
buy paper products: tree $xxx, packing $xxx, etc
buy milk: cow $x, packing $x, milking/squeezing cost $x, etc...

Lol...was juz kidding on d last 1...well, tatz juz wat i think lar...paiseh

i do tat when buying a set of PC... common wat... car no need to count cuz usually it's definitely cheaper then u buy part by part original parts... for PSU... my fren DIY a PSU from a blown up Powerlogic Magnum 300 for the CPU fan display in the shop i working at... the air coming out of it is a lot cooler and stronger than original magnum 300... i dunno wat he did or how though... but when comes to assembling a PC he is pulak...

haha, at last someone notice there's an additional cost besides the direct material & direct labor cost, the overhead cost

warranty.. support?

What RnD, all switchers are the godamned same. If you want a design, it's already included with data sheet that comes with the main regulation chip, then just trim trim here, trim trim there, and hey! You're done. It's like telling me that building a linear power supply requires a gazillion bucks of RnD , RnD is usually left to chipmakers who come up with topologies that suit their chips, PSU makers just eat the specs and schematics and try to work around them. That's the way it works in real life.

Power supply design isn't complex. Cost cutting is, because if you have all the parts to work with, you can get away with bloody murder. It's the problem that companies wanna make money and cut down at the same time. It's like the question of how can you perform proper voltage clamping without the use of a proper IC regulator with adjustable feedback sense? Simple, you use Current Sense resistors and Zeners. But of course, you take an extremely large hit in the stability department.

Since i'mma so nice and i don't care about the millions it costs to develop a PSU , here's a block diagram of mah PSU free for you


The secondary electronics industry relies on the innovation of bigger firms, it has always been that way, and why do bigger firms tolerate it? Well, if you give the customer a design where by you can only implement your chip in it, you win big time! Open up an FREE datasheet out there for a Switching regulator, everything's already there lah. And of course looking at the money these buggers make, it still doesn't justify anything because Power electronics isn't rocket science and heck there's always PSPICE.

This post has been edited by empire23: Jul 12 2007, 07:29 PM