Ben Eater 6502 Kit — Day 5

in Project HOPElast year (edited)

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Day 5 and we are still building a clock. But today I finished the clock module. It was fun subproject. Tomorrow I start with the actual computer.

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The parts needed

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Placing the integrated circuits.

God that I compacted the placement of the 555 circuits yesterday. There is not much space left in the board.

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Wiring the clocks and switches

Yellow are the two clocks, white is the switch and orange is the inverted switch.

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Wiring the rest and testing

Everything seems to work. As in the original video I attached the LED without a limiting resistor. You can do this because the SN74LS08N has an internal resistor limiting the current. However that's a fairly low resistor of only ≈100Ω making the LED far to bright.

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Now with a resistor for the blue LED

I decided to add a 220Ω resistor to the blue LED like the yellow LED. Even with about ≈300Ω the blue LED is brighter than the yellow LED.

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Testing manual clock off

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Testing manual clock on

After the test I added the suggested decoupling capacitors. I left the yellow LEDs in place since the clock is will be used for the 65C02 project and not the 8 bit breadboard CPU project. After I added the capacitors i redid all the tests.

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The LEDs from left to right:

  1. Adjustable clock
  2. Manual clock
  3. Switch, on = adjustable clock used, off manual clock used
  4. Blue LED final clock output.