Recently I started building circuits on bread boards. Nothing advanced, mostly stuff like full adders, ripple counter, etc. I am noticing some interesting behavior from the circuit though. I'll get different behavior from my circuit without changing any of the circuitry. For example I built a ripple counter with a 555 timer the other day and it was working fine. Today when I turned it on it wasn't working the same (all the LEDS were lit up at the same time). I turned the power supply on and off a couple of times and pushed all the pieces firmly into place and it started working the way I wanted again. What I am wondering is what may cause this? Is it common for circuits to require fiddling with to get them working (even when they were working previously and you didn't change any of the circuity)? All the parts I bought were the cheapest ones I could find on Ebay so I am wondering if maybe my breadboard or ICs have problems. Is there any way to check that?
Electronic – Inconsistent behavior from circuit on breadboard
breadboardprototyping
Related Solutions
Areas where the common breadboard does poorly:
- High voltage
- High frequency (above 10MHz)
- Where the additional breadboard capacitance would present problems (oscillators, etc)
- Where glitches due to poor wire connections would result in poor operation
- Where most of the parts are not through hole 0.1" (2.54mm) centers
- For anything but on-the-bench prototyping (ie, don't take it out of the lab and expect it to work)
- Sensitive analog electronics, such as sensor usage
Here's a picture of a board which had some headers forced into it which were too large, damaging the contacts:
The outer rows of the Sharpie'd area make intermittent contact, so we avoid the whole section. Notice that some of the numbers are rubbed off, and also notice the burnt spot at the top of the picture where something burned up.
The breadboard still has two other middle sections, and this section is only 20 rows tall, so that leaves 172 good rows. On a university budget, that doesn't merit replacing the board. If you are demonstrating breadboarded circuits to a client, you should probably replace the whole thing.
By the way, this board is at least 8 years old, and still works fine except for the indicated area. I've only been around it for three years, but no one has had any problems with it that I've heard of.
Best Answer
A picture is worth a thousand words, showing us what you have might give you a more targeted answer.
Electronic components are made to be predictable, random behavior is rarely desirable.
I assume you are using a solderless breadboard? If it or your components are dirty/oxidized, it might lead to poor connection and erratic behavior. Also make sure that all your components are properly inserted in the breadboard.
A multimeter in "continuity" mode will definitely help you spot issues. Also keep in mind that very high value resistors (1+Meg ohm) are close to the resistance of your (dry) skin, so touching the circuit while it operates can change its behavior. Similarly, depending on your circuit, capacitors can retain a charge for some time, so if you plug/unplug relatively fast, you might have different base conditions for your circuit every time. That's only two possible anomalies out of many more.
My advice, keep tinkering, make good observations, and try to find a logical explanation to the behavior you see. Then test that hypothesis and repeat until you have the behavior you are expecting. Have fun and learn a lot of stuff in the process, the more you do it, the faster you get!