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Step 3Control Switches
You need to be able to set the time. I used three microswitches I salvaged from an old stereo, mounted them to a bit of veroboard (or stripboard) and gummed the switch assembly using hot glue to the case.
The first switch selects the time set mode, the second selects the digit and the third increments the digit. After changing the time select the first switch again and the clock will run.
The ribbon cable from the switch has 5 lines, vcc/gnd and the three switch inputs. Each switch is momentary closed. On size connects to ground, the other to the switch input line and a resistor pullup to vcc. In other words the inputs are normally high, then pulled low to activate. See the schematic for details on the wiring.
On thing that was useful in using veroboard was that the board itself because the drilling template for the switch holes. Small holes were drilled in exactly the right positions, then squared out with a file. It made a nice fit.
The first switch selects the time set mode, the second selects the digit and the third increments the digit. After changing the time select the first switch again and the clock will run.
The ribbon cable from the switch has 5 lines, vcc/gnd and the three switch inputs. Each switch is momentary closed. On size connects to ground, the other to the switch input line and a resistor pullup to vcc. In other words the inputs are normally high, then pulled low to activate. See the schematic for details on the wiring.
On thing that was useful in using veroboard was that the board itself because the drilling template for the switch holes. Small holes were drilled in exactly the right positions, then squared out with a file. It made a nice fit.
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