TRAFFIC LIGHT COUNTDOWN TIMERS HOW TO
TRAFFIC LIGHT COUNTDOWN TIMERS FREE

Who is right on this?Ī: By a show of hands, how many of you, when you see a pedestrian traffic signal with a countdown timer, look at the remaining seconds, calculate whether you can cross the street that fast, and then make a run for it? You can all put your hands down now.īefore we get into pedestrian signals with countdown timers, let’s do a quick refresh on a traditional pedestrian signal. They seem to think that they are okay to start across as long the seconds are showing. I see pedestrians constantly starting to cross when the red hand is lit and the seconds are showing. My understanding is that when a pedestrian comes up to the corner to cross the street and the red hand light is flashing, they are not supposed to start across.

For example, you know how 24-hour clocks use a dual or quadruple input AND gate to get 59 (60) seconds to reset, likewise with 59 (60) minutes and 24 hours by using the a to g outputs to feed the 4 AND inputs which makes the AND output reset the necessary counters and clock +1 on the next counter.Q: I have a question on traffic signals for pedestrians. Maybe you just need a standard logic IC of some sort (NOT/AND/OR/NAND/XOR/whatever.) to complete your circuit function instead of multiple 555s. I do this when a circuit is getting the better of me (which happens quite often!), it helps to see the wood from the trees, and to remember the mechanics of a circuit apart from the distraction of incorrectly flashing LEDs! Both plans of attack usually help a lot to see what's happening/what should be happening, and what may or may not be missing for that result to happen. Just remembered, last thing is: Have you tried doing a truth table for your circuit, or even just a block diagram of 'in' and out' signal paths, and looking at it from the point of view of whether it is combinational logic, sequential logic or a mixture both? (Quite a few 'simple' circuits are a bit of both).

TRAFFIC LIGHT COUNTDOWN TIMERS FREE

I'm happy to help if I can, feel free to ask if I can actually help, but not happy to waste your time with bad/useless advice, my friend, that would be unfair to you.

TRAFFIC LIGHT COUNTDOWN TIMERS HOW TO

Perhaps for what you are doing a PIC would be nice for the more complex functionality you may need, and to use far less parts, but I drag my feet in that regard as 6 months to learn how to configure and code the things just to finish a circuit you are already halfway through is maybe not worth it.Īs I'm not much use to solving your puzzle I suspect, I hope maybe these links can help you: Besides that, for something else I needed to use 3 timers to do a set/reset function for a hands-free stopwatch circuit, it wasn't possible with less.Īt first glance it looks like that circuit works with a switching input signal, or one per traffic light sequence. I ask because I've been working (off and on) on a circuit that uses 4017s and 555s to control 3 motors, and it would only work with a monostable - possibly two - for the timing I need (30 seconds total, 21 seconds for one sequence and 9 seconds for the second) controlling three different astable 555s which drive the various 4017 cyclical counts. To be honest I'm not familiar with this BCD counter or the 7-segment BCD decoder,(I know the 4026/4033, 4511, 3161 and another I can't remember now), but I have been looking at the datasheets for both your ICs, and at other 74192/7447 circuits (for what that's worth), and something I don't know about the 74192 so I wonder: Are you trying to get three different timed pulse signals from 1 astable 555? If so, can your circuit/47192s create the 3 distinct time sequences from 1 astable 555 pulse? If you haven't quite resolved this yet, if you don't mind could you maybe re-post the schematic larger/as a jpg, please, and I'll be happy to scratch my head for a while, not promising anything but I'll gladly give it some thought if you want. Okay, I'm having difficulty seeing the details of the pin uses in the schematic, when I enlarge it gets blurry - sorry.

Traffic light countdown timers