MikeB Posted December 10, 2005 Report Share Posted December 10, 2005 Hey, i have recently built the 7 segment LED counter from this website (http://www.electronics-lab.com/projects/misc/012/) and i couldnt make it count. What exactly is a TTL pulse and how can i provide it to the counter to make it count up?Thank you very much. Quote Link to comment Share on other sites More sharing options...
EdwardM Posted December 10, 2005 Report Share Posted December 10, 2005 Hi MikeBTake a 4.7Kohm resistor from +5v and connect it to the input. Connect a switch between input and ground.This circuit will count every time there is a transition from high to low voltage on the input pin. The first thing you may notice is that each time you hit the switch and expect an increase of 1 in the displayed count, you get several counts - this is switch bounce and can't be avoided unless you add a debounce circuit first. There are also many other kinds of input that you can use which don't suffer the bounce problem to the same extent, for example, optical or magnetic switches.Hope this helpsEd Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 10, 2005 Report Share Posted December 10, 2005 Also add a 0.1uF ceramic and a 10uF electrolytic supply bypass capacitors to the circuit. ;D Quote Link to comment Share on other sites More sharing options...
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