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enter image description here

I made a circuit of experiment 19 from Make : Electronics 2nd Edition. It's called "time transitor."

I made the first part of this circuit by referring the upper pictures, but when I connect the electricity, it does not work at all.

I want to figure out what's wrong with it.

enter image description here

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    \$\begingroup\$ Please link to the original project to see the schematics. We can't possibly know from the picture what the circuit is supposed to do or how things should be connected, not to mention we can't even see what those chips are. \$\endgroup\$
    – Justme
    Nov 30, 2020 at 5:50
  • \$\begingroup\$ Thanks for the advice. The upper one is 555 timer, the second one is 4026B chip, and the last one is 7 segment device. I'm really sorry for the broken English. \$\endgroup\$
    – Wright Mark
    Nov 30, 2020 at 6:04
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    \$\begingroup\$ That's not a very good tutorial, for example the single resistor on the LED display is poor design. Anyway start at the output and work back, see if you can light a segment bypassing the 4026B, then get the 4026B to display anything at all, then get the 555 clocking it. Are you sure you have the right display and have not mixed up common anode with the needed common cathode? And show your power source. Buy a voltmeter if you do not have one and check key points in the circuit. \$\endgroup\$
    – Chris Stratton
    Nov 30, 2020 at 6:25
  • \$\begingroup\$ Chris, thanks for the answer. If you don't mind, can you give me some feedbacks online.. for example like by using zoom to see directly what's wrong with my advice. Because, I don't major in electronics, I'm almost illiterate about the circuit... \$\endgroup\$
    – Wright Mark
    Nov 30, 2020 at 7:27

2 Answers 2

Reset to default
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I see one thing that looks wrong.

enter image description here

See the break in the blue line on the breadboard? That means that there is not a connection between that line and where you connected the ground. You have to jumper over it if you want it connected.

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  • \$\begingroup\$ Can you explain a little bit more? I'm not sure what the red point is.... \$\endgroup\$
    – Wright Mark
    Nov 30, 2020 at 8:37
  • \$\begingroup\$ The resistor is not connected to ground, so no LEDs light. \$\endgroup\$
    – Spehro Pefhany
    Nov 30, 2020 at 8:38
  • \$\begingroup\$ It's connected... Do you think there's nothing wrong on that circuit of the picture from the book I posted on this website? \$\endgroup\$
    – Wright Mark
    Nov 30, 2020 at 8:53
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    \$\begingroup\$ @WrightMark try moving the resistor lead on the right up the line 3 holes. Let us know how you go \$\endgroup\$
    – ezra_vdj
    Nov 30, 2020 at 9:24
  • \$\begingroup\$ Can you please give me some feedbacks online by chatting or something else..? \$\endgroup\$
    – Wright Mark
    Nov 30, 2020 at 9:29
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The breadboard power line is physically disconnected between the gaps. Add a jumper cable as indicated in the picture below (red line). enter image description here

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  • \$\begingroup\$ Staples work too, often enough you want the blue and red lines to be continuous powerlines on breadboard anyway. Doesn't fall out as easily. \$\endgroup\$
    – Mast
    Nov 30, 2020 at 19:53

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