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The question had to do with the flip-flop and what happens to the inverted output. That drives the discharge transistor, which has been the subject of some discussion in the past on ETO. Anyway, I found this diagram on an educational site (but lost the actual URL), which I think is a pretty good drawing:
I like the video. How about putting it in the video section? Then it wont get lost in here in a few weeks It never occurred to me that you could make a 555 from transistors, i might have a go at doing this over xmas.
Oh, how far we have come. There are a lot of us here who remember early IC's being advertised with the equivalent number of transistors. Moore's law added some formality to that (http://en.wikipedia.org/wiki/Transistor_count ).
It is fairly remarkable (from an analog-phile's point of view ) what functions a 555 can be configured to perform. From my experience:
1. Self triggered One shot mono-stable (ms)
2. Triggered ms
3. Self triggered a-stable (as)
4. Triggered as
5. Self triggered flip-flop (ff) (selectable On or Off initial state of output depending on use of the Reset and Trigger pins)
6. Triggered ff (as above)
7. Single or dual triggered ff (in SIM single trigger worked, but in real life never could get it to work )
8. Cascade two of them for dalayed timer (also self or ext. trigger) Cannot cascade three or more.
9. When used in conjunction with a CV pin bias: Comparator, e.g., level sensor, hysterisis control, etc..
5. & 6. make a very handy Solid State latch, e.g., as a bounceless, low power Vcc supply (for small mechanical relays, other 555 circuits, etc.).
3. & 4. are configurable for both frequency and pulse width.
Did discover that in SIM for an ff circuit, the use of the Reset pin (as a trigger) was simply a bias issue, but in real life I needed to add a cap to ground (from the Reset pin) for output state stability.
Additional combos of all of the above.
No doubt more uses that I haven't made use of thus far...
Back in 1958 got the "Span Master' kit for Christmas, then in 59' bought the T-50 xmitter and the R-100 rcvr kits (my first novice Ham set, $$ from a paper route). Got all my parts from Allied Radio in Chicago. Still remember the smell of the components when I opened the box (not really different from today with a box of goodies from Digikey!).
I cannot get the first link to work. The second is an animation, and they generally turn me off, but it has been swiped by many others including the third. I wish I could find the original source for the animation. It looks like something Tony van Roon would have done, but apparently that is not the case (http://www.sentex.ca/~mec1995/gadgets/555/555.html ).
I like Dave; he's a lovely guy when you get used to him, and he puts A LOT of hard work and detail into his videos; detail that most people overlook, forget or just cannot be bothered with. I admit, however, watching this kit being built *in realtime* was one of the most tedious things I've ever suffered... but I love 99.999% of his videos; he's a good bloke, a nice one.