In a classic case of “use it or lose it” I cannot remember any of my electronics training and transistor theory is a purple haze. Basic electricity is a snap, but even after looking at my school notes and books, I am tron idiot now.
I turn to the SDMB because years ago, kids in Radio Shack were all savants. Now, they are burger flipper rejects that can only ripple off gameboy details.
Situation:
My motorcycle (12 volt system) has a twin bulb brake light system. My modulator flashes both lights simultaneously and after a few seconds, holds them steady on. There are other modulators that will alternate the bulbs continuously. There isn’t a modulator that I can find which combines the two.
Question:
Is there a relatively simple and possibly inexpensive relay setup that I can put together that will alternate the bulbs at a rate of say, three flashes each per second, then hold them steady after about 5 seconds? If it starts involving IC chips, or building circuit boards, forget it. I’m too stupid in my older years. Something is telling me that it should be simple, but that might just me my educated past trying to swim through the belligerent drunk brain cells.
I can’t think of a simple way to do this that doesn’t involve some sort of simple logic circuitry. Getting them to flash alternately is pretty simple using a DPST relay and an automotive turn-signal flasher module, but getting them to both stay on after a fixed time limit is tricky without some kind of timing circuit.
Oh wait, on second thought, there is. You can use your existing flasher, but use a normally closed relay on one of the bulbs to invert the state, using the power from the first bulb to activate the pulldown coil. I can draw a diagram for the hookup if you want.
Yeah **Q.E.D.[/]I’ve been going through my logic notes and realized that they are very illogical. I just don’t know components anymore, which is the main problem. It’s right there in the dark shadows, but I just can’t get to it. It’s driving me nuts.
I already thought of just throwing a relay into whats there but came to the same conclusion. Don’t know how, but I knew it wouldn’t work.
Sure, I love burning my fingertips off with a soldering iron! I’ve got a quart of RMA flux just sitting in my fridge doing nothing. Go ahead and email me. I’ll run some circuit simulations on PSpice and see what happens.
An SCR really is a “dc version” of a triac. (More properly, a triac is an ac version of an SCR).
An SCR only needs to have a pulse applied to the gate to make it turn “on”. After that, it act like a diode. Until the current flowing through it is stopped by some external means.
A triac, in effect, is just two SCRs connected in inverse parallel.
A triac works really well in controlling ac currents because the current through it is automatically stopped twice per cycle, just by virtue of the fact that it’s ac.
SCRs have more limited application, because the dc current flowing through them, in most situations, doesn’t stop.
