I was looking at 555 timer circuits. I can see what this does...it is supposed to turn the transistor on and off at about 10khz. But I haven't really looked into transistors yet. I'm kinda learning stuff either as I need it, or, like now, when I see something that raises a question. I guess the one closer to the IC is like the grid resistor on a vacuum tube? They haven't labelled them...what does the other one do? The one between the base and emitter? How would I calculate the values of both using this circuit as an example? Oh, and how critical is it? Surely there's a wide range of what works? I don't know how this will react as the battery voltage drops from the 9.8v or whatever of a fresh battery, but I'm just interested in the actual maths, not their specific circuit. I guess if they just use a value somewhere between a fully charged battery and a "dead" battery, everything will be within acceptable tolerances?
I haven't looked into transistors much, but I thought to use them as a switch, you just needed a current flowing from base to emitter, and that as long as it was enough current for that tranmsistor, then collecter to emitter would simply function like an open switch. (or closed..can never remember which way round, because it's a bad choice of word) Did I miss some things? I guess I did, bceause I don't see a point in those resistors based on what I've read so far. Is there some relationship between the base to emitter current and the collector to emmitter current that must be kept within a certain range? Is that the point of the resistor on the left?
Then, what's the one from base to emitter for? Is it some non-essential thing, or does it have to be a specific value?
It's not easy learning electronics from the ground up, because all the knowledge out there is not arranged into a logical order. Almost everything you can learn, requires you to already have learned something else
Oops. Should have checked how you post images on thius forum first
GRrr. can't seem to get it to work.