| ??? 07/14/04 17:06 Read: times |
#74240 - RE: Ramping instead of zero-crossing Responding to: ???'s previous message |
Russell Bull wrote:
------------------------------- Can we define what the load is? A TV, Stereo, lights (how many watts) and how fast do you want to switch them. Any of the above and similar (say, the switch would be installed in a home socket, where I can plug anything in. Obviously such sockets are rated about 3A by themselves but we should take "dumb users" into consideration, say, a housewife who plugs whole kitchen with microwave oven, fridge and electric oven, but in this case the device is not required to work, just to fail relatively harmlessly (no fire, shrapnels all over the kitchen, lightnings, smoke etc. Say, just a burnt breaker.) The hardest part is choosing which one! Many years of my professional life was designing light dimmers controlling kilowatts of lights. If I only wanted to switch a load, I would use a relay.
Relays have some serious minuses of quite high triggering current (too much for your average TTL buffer), some of them are audibly noisy, and generally through mechanical parts they are usually considered less reliable than "solid state" devices. Although you're probably right and as an amateur I shouldn't try any modern science miracles, especially that I ask for a -simple- solution... Dissipation is a problem though for large loads and you need to have a bit of protection around the devices to protect against short circuits and high voltage spikes. Diode array, breaker, air gap, a radiator plus thermal protection... anything more? That's my ten cents worth! I'd say several $k in value but it's just me, thanks :) |
