Make something simple with 3 binary timers
(http://www.radioshack.com/nte74ls163a-ic-ttl-binary-counter/55051075.html#q=counter&start=1).
So you would need an oscillator. You can make one with a couple of
cross-coupled transistors or just use a couple of cross-connected
flip-flips.
Feed the timer into each of the counters that is enabled by each switch
plus the output of the previous counter. If the counter overflows
before the next switch is pressed, then nothing happens.
That make sense?
bp
<part15sbs{at}gmail{dot}com>
On 1/8/2015 5:09 PM, Mark - Myakka Technologies wrote:
I'm working with some kids on a school project. They want help with a
simple circuit design. Bare with me as I explain this. My circuit
design skills are VERY basic.
We will have 3 momentary switches (1 2 3). If they are pressed and
released in the order of 3 2 1, we need it to trip a relay and keep it tripped
for
about 4-5 seconds. Any other order and the relay stays closed. Also,
there should be a reset timer such as if 3 and 2 are tripped, but
nothing happens in x seconds system resets.
This will be running off of 4 AAA or 4 AA batteries. This device will
be used for 5-10 minutes at a time.
I'm trying to keep it basic as possible. These are 6 & 7 graders with
zero electrical knowledge. If the circuit get too complicated, their
eyes will just glaze over.
I was thinking about something with capacitors. I know they store and
release energy and have some timing specs.
