EDIT.
Good work, I've recorded the voltages and currents for future reference.
I replaced the attachment as forgot to include the Reset button in the circuit.
Circuit description.
Turn on Power, press Reset button, all counters are preset to Zero. Display shows 000.
Press Up button, U/D is pulled Low, the 100 nF cap starts charging towards +5 Volt.
When the cap voltage reaches the upper threshold of IC4a (after about 50 milliseconds, IC4/3 goes High and IC1 increments fro 0 tp 1. The display shows 001.
At the tenth press of the Up buitton, IC1 goes from 9 to 0 and IC2 goes from 0 to 1. Display shows 010.
If the Down button is pressed, the U/D input remains High and, after the delay, the counter decrements by 1.
The 50 ms delays have 2 functions.
1. to allow time for the contacts to settle in order to avoid contact bounce problems.
2. to ensure that, when the Up button is pressed, U/D is pulled low before the clock goes high.
I have not included the interface to the Tx. You will need two 74HC05 hex inverters for this.
I suggest you build the counter first to gain experience. Note my previous comments about the display and display driver.
I suggest that you build it on a prototyping PCB.
I don't know what is available in the US, but in Australia the electronics shops sell various types of prototyping PCBs.
The one I prefer is sold by JayCar, see the "IC Experimenter's board" www.jaycar.com.au. Catalogue number HP-9558.
They have an internet shopping site in the US www.jaycar.com.
Good work, I've recorded the voltages and currents for future reference.
I replaced the attachment as forgot to include the Reset button in the circuit.
Circuit description.
Turn on Power, press Reset button, all counters are preset to Zero. Display shows 000.
Press Up button, U/D is pulled Low, the 100 nF cap starts charging towards +5 Volt.
When the cap voltage reaches the upper threshold of IC4a (after about 50 milliseconds, IC4/3 goes High and IC1 increments fro 0 tp 1. The display shows 001.
At the tenth press of the Up buitton, IC1 goes from 9 to 0 and IC2 goes from 0 to 1. Display shows 010.
If the Down button is pressed, the U/D input remains High and, after the delay, the counter decrements by 1.
The 50 ms delays have 2 functions.
1. to allow time for the contacts to settle in order to avoid contact bounce problems.
2. to ensure that, when the Up button is pressed, U/D is pulled low before the clock goes high.
I have not included the interface to the Tx. You will need two 74HC05 hex inverters for this.
I suggest you build the counter first to gain experience. Note my previous comments about the display and display driver.
I suggest that you build it on a prototyping PCB.
I don't know what is available in the US, but in Australia the electronics shops sell various types of prototyping PCBs.
The one I prefer is sold by JayCar, see the "IC Experimenter's board" www.jaycar.com.au. Catalogue number HP-9558.
They have an internet shopping site in the US www.jaycar.com.
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