Breadboard Noise

[bugmenot]

I'm designing & breadboarding various audio circuits, and I find that they work initially, but if they get bumped the wrong way, or just put away in a box and taken out later, they often don't work properly, are very noisy, or don't work at all.

This can make my electronics hobby quite frustrating.

Do all breadboarders have such troubles? Are breadboarded circuits extremely noise sensitive and physically fragile? Sometimes if I just put my finger near a pot on the board to adjust it, the circuit goes crazy until I take it out. Sometimes, if I just switch a component, the circuit shows noise (like a differentiator), even if I put the orginal component back? What am I doing wrong?

Some details which may help:
* I'm using rather cheap breadboards, but they do seem to hold the components in
* I'm using an Elenco trainer for power supply and func. generator, which I connect to my breadboards with long alligator clips connected to small pieces of jumper wire
* I need to clean things up and put them in a box in between work sessions
* My circuits are often my own design, so I'm not sure if it's my designs which are fragile, the components, or my construction

 

[Pommie]

I use breadboards all the time and have no problems at all. I suspect your breadboarded circuits are unreliable because they look more like a birds nest than a circuit.

Attached is how I build a typical breadboard circuit.

Mike.

 

[crutschow]

If it works at one time and then not another it would appear to be bad or intermittent connections. Perhaps you breadboard is not making good connections to the leads. A picture of your breadboard would help us determine what you might do to improve the reliability.

 

[audioguru]

I never use a breadboard. Their connections are intermittent and their hundreds of long wires are antennas for mains hum and other interference. Their capacitive coupling to nearby connections is high.

 

[Pommie]

I have never had a problem with capacitance. This is probably because I normally don't go over 20MHz but I have done USB stuff running at 48MHz without any problems. Besides, how much capacitance can there be between 2 strips with a few square mm of area and separated with over a mm of plastic. I really think the capacitance problem is very overstated. I was curious and so I worked it out, 40mm² (10x4) area and 1mm of some plastic (say polycarbonate - Relative permeability 2.8). I get 1pF. Completely irrelevant unless your building RF circuits. For the curious I did (8.85*10^-12 * 2.8 * 40*10^-6)/1*10-3.

Sorry if I sound like a broken record.

Mike.

 

[audioguru]

The capacitance between two pins on a transistor is a few pF. Then a strip of connectors in parallel with another strip beside it is a few times maybe 5= 15pF.

The very long connecting wires on a breadboard have capacitance to other wires and make great antennas for picking up interference.

The long wires also have inductance.

 

[bugmenot]

Will try to get some pictures, and then post them.

 

[bugmenot]

I use breadboards all the time and have no problems at all...Attached is how I build a typical breadboard circuit.

Mike - that's a very neat construction indeed. Mind if I ask for some pointers:
* What brand of preformed jumpers do you use? I tried the Elenco ones and could never get them to fit, so instead just use flexible wire.
* What brand of breadboard?
* How do you connect up power, signal, scope probes, and things like speakers which don't fit into a breadboard? I use alligator clips attached to jumper wires which I insert, and so I end up having 4 or 5 of these hanging off the board.

 

[RadioRon]

I have never had a problem with capacitance. This is probably because I normally don't go over 20MHz but I have done USB stuff running at 48MHz without any problems. Besides, how much capacitance can there be between 2 strips with a few square mm of area and separated with over a mm of plastic. I really think the capacitance problem is very overstated. I was curious and so I worked it out, 40mm² (10x4) area and 1mm of some plastic (say polycarbonate - Relative permeability 2.8). I get 1pF. Completely irrelevant unless your building RF circuits. For the curious I did (8.85*10^-12 * 2.8 * 40*10^-6)/1*10-3.

Sorry if I sound like a broken record.

Mike.

The capacitance between adjacent rows on my breadboards is 3.3pF and from any connection row up to the nearest supply rail is 1.3 pF. This has caused me grief in analog circuits mixed with fast switching circuits or any clocked logic. It usually isn't a problem with op-amps, linear regulators, and low frequency discrete circuits. It also hasn't been a problem with purely digital circuits on a modest scale because of their built-in noise margins.

 

[ericgibbs]

Mike - that's a very neat construction indeed. Mind if I ask for some pointers:
* What brand of preformed jumpers do you use? I tried the Elenco ones and could never get them to fit, so instead just use flexible wire.
* What brand of breadboard?
* How do you connect up power, signal, scope probes, and things like speakers which don't fit into a breadboard? I use alligator clips attached to jumper wires which I insert, and so I end up having 4 or 5 of these hanging off the board.

hi,
I fix my project boards to double sided pcb [use off cuts]

Cut the pcb so you have about 1 inch oversized on the project board, that is a 1 inch pcb border.

Solder 0V/Gnd wires to the pcb and push the other end of the wires into the project rails you plan to use a the 0V rails.
You now have a grounded back plane.

Use short lengths of terminal strips, the type you normally screw to a panel and has vertical tags to which you solder wires.

Solder the terminal fixing tags to the pcb [ all on the top side of the pcb!]

Use the 'free' terminal tags to connect long twisted wires to your bench power supply.
From these tags solder power wires and push the free ends into the project board lines that you are using as power rails.

Now solder on the terminal strip electrolytic and ceramic decoupling caps, using the pcb as 0V/gnd.

I usually mount two project boards on one back plane pcb, sometimes 3.
This gives a firm base for holding the project boards together, especially when connecting wires from one project board to another.

I use these boards for work from mVolts analog signals, digital logic/PICs upto 20MHz with NO problems.
I hate to admit this but my project boards have been in regular use for about 20 years, bought from Jermyn industries.

Always use clean, short lengths of TINNED solid copper wire for the interconnections. Use old telephone wire.

DONT force in oversized component leads.

If the passive components you use are on 'strips', cut off the end bit of wire thats covered by the strip..
Some strips leave a tacky residue on the wire, you dont want that in your sockets.

OK.?

EDIT: at the other end of the pcb I solder another terminal tag strip.
I use this to wire test leads into the project board and the scope/meter hang on this terminal strip.

 

[bugmenot]

Pretty neat, Eric. Have any pictures? (Would help visualizing it.)

 

[ericgibbs]

Pretty neat, Eric. Have any pictures? (Would help visualizing it.)

hi,
Whats your location.?

 

[Nigel Goodwin]

I never use a breadboard. Their connections are intermittent and their hundreds of long wires are antennas for mains hum and other interference. Their capacitive coupling to nearby connections is high.

Likewise, I never use them either.

 

[ericgibbs]

Likewise, I never use them either.

hi,
'agu' said he tried them 'once' and they didn't work, to me, that seems to a very limited amount of
experience of which to base an opinion 'they are no good' in order to put others off from trying them.

I suspect you may have a wider experience using project boards and found them unsuitable for your use.

But there are many qualified engineers/programmers who use them on a regular basis
and find them trouble free for their applications.

I think its important that 'newbies' are not put off trying these project boards by the bad experience of one or two users.

 

[transistor495]

Pretty correct
I'm very thankful to my elder brother who gifted me a breadboard when I was abt 15yrs. Before that I was making circuits as a 'spidernet' using electrical wiring copper wires for interconnection.
After that I've tried a lot of circuits including audio and radio/RF. I havn't feel any difficulty and most came up with my original expectations. According to me parasitic cap is working well on theory, but practically almost one will work except VHF.
My all fm xmitter circuits worked well on breadboard but of course, their working frequency changed when I made the prototype on pcb. A superregen may not work on a breadboard, can't trust and will make unnecessary oscillations.
Overall, breadboard is a great invention. Who discovered that. Who is that wise person??

 

[Pommie]

Mike - that's a very neat construction indeed. Mind if I ask for some pointers:
* What brand of preformed jumpers do you use? I tried the Elenco ones and could never get them to fit, so instead just use flexible wire.
* What brand of breadboard?
* How do you connect up power, signal, scope probes, and things like speakers which don't fit into a breadboard? I use alligator clips attached to jumper wires which I insert, and so I end up having 4 or 5 of these hanging off the board.

I make all my own jumpers from 0.6mm diameter wire. I have a few different coloured reels of wire and can make them quicker than most people can strip a piece of wire to a random length. The above board would take me around 1 hour to make which I consider time well spent as I can then be confident that bugs are in code and not hardware. The breadboards I use are just a cheap brand (wish) from the local electronics store. For connecting things that don't fit a breadboard I solder on SIP connectors or use breakout boards. In the above photo the LCD and the IDC both have connectors soldered to them.

Mike.

 

[ericgibbs]

Pretty neat, Eric. Have any pictures? (Would help visualizing it.)

Hi,
As per your PM, I thought a simple drawing would help.

Credit for the actual project board used in the diagram goes to Pommie aka Mike.

OK.?