Daryl Musashi
New Member
Hello everyone,
I am fairly new to electronics and going to make my first larger project at the moment. One main element of it is a 2 x 7-segment-display counting down from a certain value to 0. To realize that I used a 555-timer in astable mode to generate the pulses for the first of my two 4029 ICs. Furthermore I use 2 x 4511 ICs to convert the input for the 7 segment displays.
At the moment I have a running circuit, which counts down from 99 to 0. Now I want to modify the starting value, which can be achieved by putting "high" or "low" to the 4 jam inputs (4, 12, 13, 3) of IC 4029. For example if I want to start with "5" the code for the jam inputs is 0101 (for the jam inputs 4, 12, 13, 3) - I hope I am right?
But in detail I cant get the circuit work. I can try every possible combination of "high" and "low" to the jam inputs 4, 12, 13 and 3 - it always starts counting from 9 to 0 !
I thought for a time that the "Preset Enable" pin needs a permanent "high" if I want to define a certain starting value, but the counter does not count any more in this case. But this is no surprise referring to the data sheet of the IC 4029 I realized, as this behaviour is cleary described in the general description section.
Can anyone please guide me what to do in order to achieve a countdown from a certain value? A simple circuit diagram as an example would be sufficient, too.
I am fairly new to electronics and going to make my first larger project at the moment. One main element of it is a 2 x 7-segment-display counting down from a certain value to 0. To realize that I used a 555-timer in astable mode to generate the pulses for the first of my two 4029 ICs. Furthermore I use 2 x 4511 ICs to convert the input for the 7 segment displays.
At the moment I have a running circuit, which counts down from 99 to 0. Now I want to modify the starting value, which can be achieved by putting "high" or "low" to the 4 jam inputs (4, 12, 13, 3) of IC 4029. For example if I want to start with "5" the code for the jam inputs is 0101 (for the jam inputs 4, 12, 13, 3) - I hope I am right?
But in detail I cant get the circuit work. I can try every possible combination of "high" and "low" to the jam inputs 4, 12, 13 and 3 - it always starts counting from 9 to 0 !
I thought for a time that the "Preset Enable" pin needs a permanent "high" if I want to define a certain starting value, but the counter does not count any more in this case. But this is no surprise referring to the data sheet of the IC 4029 I realized, as this behaviour is cleary described in the general description section.
Can anyone please guide me what to do in order to achieve a countdown from a certain value? A simple circuit diagram as an example would be sufficient, too.