Alright I need help drawing the diagram... I know what i'm doing and a lot of the information but I need help with the diagram. A three car race track has sensors in each lane at the finish line. As the cars cross the finish line their respective sensors respond and send a signal to a digital circut. The three "finish" signals occur in the same order that the cars finish in. The digital circut has a 3x3 matrix of nine LED's which indicate the placement of each car. You're hired by the race track committee to design and build a digital circut that will operate as described above. The LED indicators must be laid out as shown on the picture. http://img135.imageshack.us/img135/595/racetrackproblemkr7.jpg [Broken] A push button resets the circut and extinguishes all lit LED's. Design Hints: *The signals from the track sensors are 10mS HIGH pulses. One pulse per race. *Each LED is lit by an R.S. flip-flop. *A two bit binary counter will start at zero and be incremented every time any track pulse occurs. *Gating circuts are advised *remember, each track signal only appears for every race I figured that I will need: 3 monostable multivibrators 97474 RS Flip-Flops 1 7476 gating chip so just so you dont think that I'm just trying to get pple to d my homework.... I need helping drawing this.. I know what Im talking about but when it comes to putting it on paper I appear to be useless...:grumpy: I've been trying to figure this out with logic and common sense but this is what I think.. I would suppose from the selection of chips needed that what I should build a matrix of 3 x 3 FF's. What I would do is to use the 7476 as a 2 bit counter, representing the placement. For each placement 0 - 2, you must decode this to a data bit for the placement row. Each car clock all 3 FF's in its column, reading the placement, and increment the counter. Ths way I clock the current position into the FF's for each car. Decoding the counter to make a running '1' is fairly easy just AND the /Q's for the first(placement 1), and then use Q1 and Q2 for the other 2(placement 2 and 3). The only thing I need to do then is to combine the 3 clocks into one signal for incrementing the counter. and I think the one shots are for Cleaning up the car signals and shortening them.