I recently finished building a circuit showcased in a beginner’s electronics book. I have included the picture of my creation below because I think it may become relevant to the question.
At the beginning of the build process, the instructions specified to add a "smoothing" 100 microfarad capacitor to be placed right by where the power supply cables were connected to the board. I decided not to bother with that step because I was using a quality power supply so I didn’t think I needed that "smoothing" capacitor (big mistake).
It wasn’t long before I started experiencing weird and inexplicable odd circuit behavior and after a lot of troubleshooting and getting nowhere, it occurred to me to add the smoothing capacitor to the circuit. As soon as I added the capacitor to the circuit the problems went away, but I found myself wondering how is possible that such a capacitor mattered so much given that my circuits uses a measly 50 milliamps of total power and I have what I think is a reasonably good power supply (Rigol DP832).
To make matters more interesting, I decided to move the smoothing capacitor away from the center of the board off to one end of the board and to my surprise the problems began again. Why such a big difference just by placing the capacitor in a different place on the board?
I decided to add a beefier 8200 microfarad capacitor (that is 82 times bigger than the previous one) thinking that this would put an end to all my problems but to my surprise once again, that still did not fix the problem. I actually had to move the capacitor back to the center of the board to make things go back to normal.
That wasn't the only issue, even with the capacitor in "perfect placement", I tried to power a small mechanical relay by using the same power from the circuit and every time the relay triggered my circuit would “reboot”.
So the question is, are all circuits that sensitive to even the smallest change in electric fluctuation? Or is the problem due to my cheesy circuit prototyping skills and an inefficient breadboard?
The IC used in the circuit are:
- NE555P (Precision Timers).
- CD4026BE (CMOS Decade Counters/Dividers).