James Knott said the following on 09/14/2010 04:04 PM:
Anton Aylward wrote:
I don't know about heavy, though. Back in the mid 70s I needed a 50W PSU for a piece of avionics I was working on. Equipment for use on aircraft was severely weight constrained, compared to elsewhere. Switching supplies weren't common until the '80s or so. Prior to that, a power supply would need a heavy iron transformers, heat sinks for analog regulators, large filter capacitors etc. IIRC, aircraft equipment commonly used 400 Hz AC, which meant power supplies could be built with smaller transformers, capacitors etc.
Indeed. But when I cranked the maths, I found that a 5V DC output that was powering the semiconductor circuitry could be best achieved with a 30kHz switcher, and as a result very small - OTS - components. This was dramatic enough at the time to get "why didn't I think of that" reactions. Even back then, the 'norm" was rectification and voltage droppers (aka resistor chains that grew hot). I still wonder why we don't see more high-frequency switchers. Someone is going to say "interference". Well, yes, but we know how to deal with that, and there's a lot of high frequency noise anyway on the power mains..... -- There are two ways to slide easily through life: to believe everything or to doubt everything; both ways save us from thinking. -- Alfred Korzybski -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org