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I am trying to build this circuit here: https://www.youtube.com/watch?v=AZb4NLXx1aM

But instead of using the same timer setup I am using this:

enter image description here

When I connect the ground pin of the CPU, the LED starts blinking very fast and the CPU begins to overheat.

Note: I do have the correct pins connected (ground, power, clk), and the 555 timer works perfect without the ground plugged in.

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    \$\begingroup\$ Please include all relevant information in the question. Otherwise the question would become useless if a link disappears. \$\endgroup\$ – zx485 Jun 6 at 16:06
  • \$\begingroup\$ Sorry, I am new to very new to all of this. \$\endgroup\$ – Jay LeCorps Jun 6 at 16:37
  • \$\begingroup\$ One clue is the 9V battery you show. The Z80 won't like that. You need to show a schematic however, since a breadboard layout does not work for analyzing what you are doing. \$\endgroup\$ – Jack Creasey Jun 6 at 17:39
  • \$\begingroup\$ I am doing a duplicate of this video: youtube.com/watch?v=AZb4NLXx1aM But with this timer circuitbasics.com/wp-content/uploads/2014/12/… \$\endgroup\$ – Jay LeCorps Jun 6 at 17:53
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    \$\begingroup\$ @zx, that's a wiring diagram, not a schematic. It doesn't show us the "schema" of the circuit so we can't easily see what it is supposed to do. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. Note that when you use the CircuitLab button on the editor toolbar an editable schematic is saved in your post. That makes it easy for us to copy and edit in our answers. You don't need a CircuitLab account, no screengrabs, no image uploads, no background grid. \$\endgroup\$ – Transistor Jun 6 at 20:59
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You don't give a datasheet to your Z80 CPU or the exact type, but it is likely that 9V clock signal from the 555 timer has damaged the Z80. Usually the Z80 devices run with 5V so they are limited to 5V signals coming in and out of them.

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