S
Silvester
- Jan 1, 1970
- 0
I'm looking for some help with a counting circuit.
I have a schematic from an OLD Radio Shack book that drives a 7490 with
a 555.
The 7490 dumps into a 7448, which in turn displays the number on a
7-segment LED.
I need a similar circuit that will count DOWN from a predefined number
- say 255 using DIP switches to set the number in binary.
The problem is, I have been unable to find anything on the internet.
I plan to use a matched pair of LEDs (IR emitter/receiver) to count
objects passing a point rather than the 555 timer portion of the
circuit.
And I need a RESET button to send the count back to 255 or what ever
number is preconfigured by the DIP switches.
Can anyone help me out?
Silvester
I have a schematic from an OLD Radio Shack book that drives a 7490 with
a 555.
The 7490 dumps into a 7448, which in turn displays the number on a
7-segment LED.
I need a similar circuit that will count DOWN from a predefined number
- say 255 using DIP switches to set the number in binary.
The problem is, I have been unable to find anything on the internet.
I plan to use a matched pair of LEDs (IR emitter/receiver) to count
objects passing a point rather than the 555 timer portion of the
circuit.
And I need a RESET button to send the count back to 255 or what ever
number is preconfigured by the DIP switches.
Can anyone help me out?
Silvester