mintx Posted September 17, 2005 Report Share Posted September 17, 2005 hi! i would like to make a circuit which is like a table hockey game... it is composed of a 74ls192, 74ls47 to make it up for the scoring system... the only problem i have is how to integrate the timer to be limited only to 2 minutes and after the time period, the circuit holds the current score, sounds a buzzer... that also happens when a player reaches a score of 9, score is hold, and sounds a buzzer. the only way to play again is to reset... please help me... i need to finish this project immediately... i know u guys can help me... Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 17, 2005 Report Share Posted September 17, 2005 Hi Mintx,Welcome to our forum. ;DDo you need the circuit for a 2 minute countdown timer?You could use a couple of 74LS04 inverters to make an accurate 32kHz crystal oscillator, and a bunch of 74LSxx counters to heat your room and make a 2 minute countdown timer.Or use a low power Cmos CD4060 crystal oscillator/counter to make 2 pulses per second and a few Cmos counter ICs to make a 2 minute countdown timer.I remember about 30 years ago Intersil made a complete 3-digit timer/driver IC. Maybe it isn't made anymore because today you can buy a kitchen cooking timer for much less cost.Use the innards from a cheap kitchen cooking timer. It has a display and everything. ;D Quote Link to comment Share on other sites More sharing options...
mintx Posted September 17, 2005 Author Report Share Posted September 17, 2005 so much tnx, audioguru! but im quite a noob in digital circuits... u suggested i could use some crystal oscilators but i dont know how to design one... ive searched info's regarding timers which could be limited on a specific time but i couldnt find the most suitable for my case... could u give me a more specific detail on this or direct me on a link which could be of use? thanks again! and im relieved i could discuss this problem with someone like you... really big thanks! Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 17, 2005 Report Share Posted September 17, 2005 Hi Mintx,A countdown timer with display is fairly complicated for a noob. In our projects section is an example of a 99 seconds count-up timer. http://www.electronics-lab.com/projects/oscillators_timers/014/index.html A 2 minute countdown timer would be more complicated. Quote Link to comment Share on other sites More sharing options...
mintx Posted September 17, 2005 Author Report Share Posted September 17, 2005 yeepp... so much of a real noob... i am just a student taking up an advanced logic circuits... and to my disappointment, explanations of my teacher are barely understandable... on lab experiments, she gives us diagrams of circuits but doesnt even give a second after to explain what she just made us do... <sigh> btw, tnx for the link... actually im just plannin not to display the time and just put a buzzer when the time reaches limit... i just hope i aint gettin to burdensome for u... i just feel so down and desperate... my running light circuit doesnt also work... <sigh> but dont worry about it... my priority is this table hockey... tnx again guru! Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 17, 2005 Report Share Posted September 17, 2005 Hi Mintx,Since you are using a timer, don't you think it is best to be able to see it progressing?How about using a 555 timer IC with a constant current source transistor charging its timing capacitor linearly. Then use an LM3914 bar graph IC to display the time stepping up or down? When the timer times-out, it would activate the buzzer. ;D Quote Link to comment Share on other sites More sharing options...
mintx Posted September 17, 2005 Author Report Share Posted September 17, 2005 wow! sounds great!!!!!! i think thats by far the best thing ive heard... rather, read... the only problem left is how to design that circuit and connect it with my current scoring system... actually i thought that the stopwatch circuit u gave me would do fine, but one problem for that is it is so hard to find those materials here in my place... Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 17, 2005 Report Share Posted September 17, 2005 Where on earth (?) are you?There are lots of ways to make a timer with difficult to find logic ICs, but 555 timer and LM3914 bar-graph ICs are pretty common nearly everywhere.Have a look at the datasheet for the LM555 timer. It shows it with a constant current source transistor producing a linear ramp. Hint: page 9 on the datasheet. ;D Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted September 17, 2005 Report Share Posted September 17, 2005 How about using a programmable device like a PLA or a PIC? Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.