I'm trying to build an LED flasher (as small as possible -- operating on a 9V battery) like this...
Here's how it works...
You attach it to the battery then program the flash sequence by shorting the terminals on top. Once you first short the terminals, the time starts counting and you have a specified amount of time (about 5-6 seconds) to program a sequence. As you short the terminals, you see a visible green LED that indicates on. You tap out your sequence and when the time is up, it stops accepting programming.
If you view it through night-vision scopes, you can see the pattern you input flashing in IR.
which I'm assuming are simple off-the-shelf logic (could be a bad assumption). I had originally thought 555 timer and shift register.
My idea for the design was that a timer clocks in your input to a shift register. The longer you short the terminals, the more 1s are clocked in. This results in a pattern of varying pulse widths that can then keep cycling through the shift register and illuminate the LEDs.
I was unable to find similar circuits on the web, so I'm not sure that's the right approach. I had although thought of individual one-shots somehow keeping the outputs high/low with something clocking them to change it based on what you input.
I can't figure out the "memory" of it, but I'd assume it's not something complex -- that's why I keep thinking "shift register". For it to work though, it would have to be many bits wide. I found some
8-pin ICs that have 16-bit serial registers in them, so if the duration of the one-shots output is 1/3 second, then the shift register would support a 5-second programming duration.Any ideas?
Thanks.