Many people don't want to build circuits. For only a little more cost than the transistor based circuits, you can build a buck driver. For some/most, the extra $15 is worth it when you don't have to build and debug the circuit.
Building a buck driver, like using the stcs1? That one is already $10 per unit, so you're already up to the cost a buck, when including the pcb and other pieces of the build.
The main reason I'm contemplating using a transistor driver is because buckpucks aren't available here and would cost $30-40 total, including taxes and shipping if ordered from usa. For about $5 I can make a transistor driver here.
I'm a little twisted as how to pick mosfets for the driver - does it matter as long as it's rated big enough for the job and is a Nfet? And the secondary transistor (small one) - Can it be any NPN?
As for dimming, I imagine a switch could be constructed that switches between a f.e. 3 resistors.. 25%, 50%, 75% and 100%. For me that would be plenty, if it's as simple as it sounds (finding the correct resistors and connecting to a rotary switch f.e.)
Edited by keli, 03 March 2009 - 07:52 AM.