Another option is 555 IC's, very easy to work with and a million circuits out there.
Rory -----Original Message----- From: Af [mailto:[email protected]] On Behalf Of Bill Prince Sent: Thursday, January 8, 2015 6:25 PM To: [email protected] Subject: Re: [AFMUG] OT - EE help please 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. > > >
