hey all i recently aquired a traffic light but the only problem is it is not wired at all, the light wires just end, there a positive for the 3 light and a common ground. i could hook them up so there's a toggle switch controlling each light, but what i really want is a circuite that controls the lights like one you see on the road. the green is on for a certain time period, then yellow then red... and then repeats. so what i am asking is if anybody knows any sites with diagrams that would accomdate this, or if anybody could design this i would be very greatfull. like i said there are the three lights (obviously) and they all run off of 120v thanx for the help everyone Eric
There a couple of ways of doing that: You could use 2 555 timer circuits and 3 realys: Attach the Red and Green to a '555 astable vibrator circuit' (switches between outputs at a specified time forever). Attach the Amber to another '555 astable vibrator circuit' (To switch it on and off forever). You would have to stick a variable resistor on both circuits (instead of a fixed) to specify the time scale (along with a capacitor) so you can tweak the times until they appear to be working together and have the right sequence. Or you coud use a PIC, to program the traffic light sequence.
I worked this up for someone else about 4 months ago: http://www.candysporks.org/~cburnett/forums/stoplight/
thanx everybody hey musirPmeaT will this circuit work on 120v ??? if not what can i change to make it so? thanx again Eric also could you make a parts list for me plz
For the timer you should figure your timing and then get the appropriate parts, but for what I designed: 3 - 10 K resistor 1 - 649 K resistor 1 - 280 K resistor 1 - 0.01 uF cap 1 - 33 uF cap 1 - 555 timer 1 - 74LS74 1 - 74LS08 3 - n-channel FETs (i.e. IRF510) To control 120 volts you can easily hook relays up to the fets so the fets turn the relay on and off. Doing so in solid-state probably won't be as straight-forward as relays.
cool thanx doing what you did what was the timing between the lights??? it went green on, yellow on, then red on, right not some weird thing well thanx again Eric
thanx for that are the three things (74ALS08N) one chip? and are the two things (74S74N) also one chip? do u have a picture of the thing completed??? im sorry but when i see a schematic i sometimes have trouble following it... but i can put it together if i know how anyways thanx for all the help Eric
Yes, the logic gates for eagle split each gate up into individual parts. Nope, but if I did....no digi cam to take a picture with. All of the pin numbers (except for the fets) are labeled on the schematics so wiring it up will be kind of like paint-by-number. Give it a shot and see how it goes. Perhaps post pics (if you can) if it doesn't wokr and we can figure out why.
alright thanx ill see if i can get some pics... i just need to get time to go to the store... the closest store that sells that stuff is a half hour drive... and i hafta work and school and christmas shopping so itll probly hafta wait till after christmas this runs off of 5 volts correct? so ill hafta get something to take it from 120 down to 5 for it and attach the relays on where the lights go... haha anyways thanx for all the help Eric
Two ways. The first is to get a step-down AC power transformer will a winding ratio of something like 1:10 which will give you 12 VAC (17 VAC peak). Then add in a rectifier to give you ~ 17 VDC peak. Then you need a DC regulator that can within stands at least 20 volts (perhaps the LM2672 by national). Or you can skip the transformer and the regulator and use a rectifier; a resistor; a cap; and a 5 volt zener. The power ratings and values are a careful balance and not as straightforward as using a voltage regulator. In fact, the analysis required is quite lengthy and quite boring and quite inflexible. So I suggest the former solution. AC => transformer => rectifier => capacitor => regulator => load. Definitely put a physical switch on the 120 VAC on the transformer, otherwise is will always draw power.
i know these parts are for the switching itself but i need the parts to do this so i am wondering which of what do i get??? hehe thanx for all your help Eric
so a "wall wart" is a power adapter? how much do they usually cost... i think it would be chaper to make that thing myslef... i am going to be selling these things to my dad's business so i would like them to be as cheap as possible first off i would like to make on for myself though well thanx again Eric
I dunno....$5-15 maybe? You would need something like a 1:10 transformer to get your 120 VAC to about 12 VAC. Then a rectifier will give you 17 VDC (peak). I know there's all kinds of neat analysis you could do to determine the right cap, but picking a large one should do just fine (perhaps 470 uF @ 30V or something similar) Then you need a regulator capable of converting said voltage to 5 VDC (I think the LM2672 does up to 32 V for the input) and associated parts. All in all, it's most likely gonna be cheaper to buy the power supply (that whole mass-production thing) and look better. Since you want to build your own, you'll have to find your favorite store/catalog and see what they have. The current requirements are going to be under 50 mA (depending on the family) for the two logic chips plus another 20 mA (or whatever) for the LED.
I've got a little C program that will do it. Random flashing, sequenced etc. It uses the parallel port and a couple of triacs to do the work.
hey say i get something like this or this, they can output 12/10 volts, from there i would need to do this? am i correct? or is there an easier way? also how would i go about hooking this all up correctlly thanx Eric
im sorry to bring up this old topic... but i have recently got a new addition to my traffic light a walk/dont walk sign... hehe well i have all the information to make the 3 light rotate like b4... but i have an idea which i would like to do... i would like it so when the green light is on the walk light is also on... when the yellow light is on the dont walk light is flashing... when the red light is on the dont walk light is on constant... so i have an idea using the circuite that musirPmeaT supplied so basicly i just need a circute for a 5 volt flasher unit well thanx everyone Eric
What do you mean acquire??? Do you mean that one drunken night out with your mates you all went to the local bar, had a great time and then when you woke up, (to the news, telling of a car crash that happened at a set of lights in your hometown, late that night) you noticed you had a traffic light at the end of your bed??
