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My question is about breadboards. I've been using breadboards for 5 years and even if they are good only for early prototypes and are not too reliable, they have always let me build what I had in mind without too many problems. I have to admit that I've always used them with digital signal (IMU/GPS), so the fact that the connection weren't 100% perfect was not a big problem. But now, that I need to use them for analog electronics (active filters), I'm facing new problems which I had never considered: loose connections. I measured a 20% voltage drop just by slightly touching a resistor wired on the breadboard.

It happened while I was trying to estimate the real value of a ceramic capacitors (they have pretty big tolerances) measuring the time constant of a RC circuit. The input signal was a square wave between 0 V and 1 V so I was expecting to see the maximum value across the capacitor rising to 1V. Instead, the maximum value across the capacitor was always 0.8 V (the frequency was very low so the time constant was much lower than the square wave period). This went on until I slightly touched the 20 kohm resistor (it has very very thin legs), from that point the circuit started behaving correctly and the capacitors has been able to reach 1 V and fully charge.

Now the real question: what is the main problem with this analog circuits? The thin legs of the resistors? The unreliability (aka bad quality) of the breadboards?

Are there thicker resistors (or components) on sale?

Honestly I'm also thinking about buying some PCBs but soldering can become quite annoying and it's harder to fix errors. How do work with analog circuits? Online I see people use almost only breadboards to explain circuits and prototypes and they work correctly.

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    \$\begingroup\$ Sometimes you can get away with using a breadboard and sometimes you can't. There are contact issues, parasitic L and C issues, current capability issues, etc. Power and analog, especially high frequency, don't mix well with solderless breadboards. \$\endgroup\$
    – John D
    Commented Jan 19, 2023 at 16:56
  • \$\begingroup\$ Inconsistency of parasitic L and C is one of the main reasons to avoid breadboards for anything but the most simple of circuits. The major benefit of a PCB is that you can have high consistency of materials and permeability, and a solid ground reference plane under your signal layer. Given how much stripboard costs in small quantities these days it's often barely more expensive to get a PCB produced by someone like JLCPCB or PCBWay than it is to buy the stripboard. \$\endgroup\$
    – Polynomial
    Commented Jan 19, 2023 at 17:19
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    \$\begingroup\$ I don't think this is about having analog or digital signal. The same resistor in same breadboard hole might just as well have bad contact problems regardless. Resistor leads may have glue residue or the leads or breadboard contacts may oxidize or just become loose after a lot of use. \$\endgroup\$
    – Justme
    Commented Jan 19, 2023 at 17:44
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    \$\begingroup\$ If the breadboard has sat around for awhile (read: years) then a significant amount of dust has likely settled inside it, just waiting to interfere with a thin component leg. I've taken them apart, blown out with compressed air, even cleaned with a toothbrush and alcohol... but how much is our time worth? \$\endgroup\$
    – rdtsc
    Commented Jan 19, 2023 at 18:31
  • \$\begingroup\$ I use stripboard and the layout is designed so that the parts are cut to length so that each strip is used in different parts of the circuit. Of course all the parts and a few short jumper wires are reliably soldered but replacement of a part is simple with a solder sucker (slurp). The rows of contacts and long wires all over the place on a breadboard are antennas that pickup interference and have inductance and capacitance-coupling. All my stripboarded prototypes worked perfectly and looked good enough to be sold as the finished product. Would anybody buy a breadboarded circuit? \$\endgroup\$
    – Audioguru
    Commented Jan 20, 2023 at 1:14

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Now the real question: what is the main problem with this analog circuits?

Dirt.

Contamination of the contact surfaces.

If you have handled the device leads, so put biological contaminants on them, then these will make your nice clean metal surfaces not so nice and clean.

You don't need body fats and salts to cause problems. Airborne moisture, sulphur dioxide, nitrogen oxides, may eventually react and coat contact surfaces.

Both together is worse than either by itself.

With PCBs, once you've soldered a component, the soldering operation has burnt off all of this stuff, the flux has reacted the oxides, and you either have a good joint, or one that looks bad so you know to try again.

The main problem with breadboards is that this happens rarely enough to lull you into a false sense of security, so that it comes as a surprise when it's actually a problem.

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