Al salaam a'alaykum Bob

09 Nov 03 11:41, Bob Lawrence wrote to John Tserkezis:

 JT>> As I've mentioned in the other message, jaycar has the LM2576
 JT>> available as one-offs, about $14 a pop. They also have
 JT>> pre-wound toroidal inductors available off the shelf, hopefully
 JT>> the right one for your application. 

 BL>  You and Brenton need a reality check. David's not going to *ever*
 BL> finish building this thing. You've got to be practical. Even my idea
 BL> of a 6V bike battery and a 5W light bulb is a bit over the top. He'll
 BL> have to plug it into a the cigarette lighter, and if David's anything
 BL> like me, he'll buy the plug and never wire it up.

Hoi! It may not happen overnight, but it will happen....

 BL>  SMPS on a PCB? Get real!

 JT>> Efficiency might be an issue, I'm using one on 5v equipment at
 JT>> about an amp (or just over actually), the heatsink is 5cmx5cm
 JT>> thinnish aluminium plate mounted within the case. It gets warm
 JT>> if it's been on for a while, but well within specs. At 3 amps a
 JT>> larger heatsink would be wise. A larger coil wouldn't go astray
 JT>> either. 

 BL>  Yair. These little fuckers are 50% efficient if you're lucky, and
 BL> the smaller they get the worse they are. 

National Semiconductor claim 70-80% efficiency....

 BL> He'll lose 10W+, which is why I suggested an ordinary series regulator as 
 BL> a viable possibility. He can just wire the whole thing onto the heatsink 
 BL> and put it in a shoe box with his other inverter.

Shoe box, other inverter?

The main SMPS would be left here in the big city where we have 240V coming
out of the socket on the wall.

The wall sockets at my "country estate" only deliver 11.5-14V

Regards,
David

--- Msged/LNX TE 06 (pre)