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Solderless Breadboard Problems And Warnings

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Hi again,

Chemelec:
I like your low ohms meter.
What kind of test current does it put out?
I have a breadboard just like that one i could test also.

Eric:
Well then all the breadboards i have are of low quality
because they all measure about the same.
What kind of meter do you use for the test?

P.S.
I'll have to check out the blondboards later :)
 
I have never had a problem with breadboards and have initially built almost every circuit on them. I am very careful and never put any power parts on them. If I need power parts then they get a PCB or veroboard type construction. I just avoid putting large conductors into the BB. The wire I use is 0.6mm diameter and I try to make them as tidy as possible so as to eliminate errors. If you start plugging thick wires into them and then try to reuse them then expect failure. However, I did buy some cheap ones once and they were terrible.

Mike.
 
Hello Pommie,

Well the problem is that when you go to buy them they dont have "These are the cheap ones" stamped on them, or "These are the good ones", they just say "Solderless Breadboard". So unless you guys that have "good ones" can state the make and model number we can not know what to buy that might work better.

I have bought several from different places and some were more expensive, but they all read about the same and give intermittent readings when the wires are jiggled a little. It's hard to believe that other makes might be so much better.
 
Hi again,

Chemelec:
I like your low ohms meter.
What kind of test current does it put out?
I have a breadboard just like that one i could test also.

100 mA on the 1.99 Ohm Range.
10 mA on the 19.99 Ohm Range.


It is Possible to make one using Lower Currents, by adding in an Amplifier circuit.
But I don't see these Current values as being a problem.
 
Last edited:
I'm passed it, all I get is remanence.

I have wisher breadboards, they seem fairly reliable, but watch out there are cheap fakes.
 
Hi,

Ok, this problem might have something to do with the CURRENT levels we are using. Recall that some switches made for higher currents do not work well for lower currents and voltages, and the same for some relays. This is why mercury wetted relay contacts came into existence (instrumentation). Relays like this will have a low current rating as well as a high current rating.
So keeping that phenomenon in mind, i believe this is what we are seeing here. My meter probably only puts out 1ma for the test or maybe even less. Some meters will put out more and so might measure the contact resistance for a *higher current load*.
Of course this doesnt rule out other possibly explanations too, but at least we can be sure this is one of them. But to be really sure i can test the same boards with a higher current level and see what gives. I am betting that there is a threshold that once reached, shows lower resistance, just like some switches do.
I once measured a switch that was installed in an electrical box with an ohm meter (standard 1ma or so test current) and it measured completely OPEN. However, turning the switch ON when in the lamp application caused the light to turn on normally. The voltage potential is higher for the 120vac line than for the 3v ohm meter so that is a possible explanation for that too. The higher voltage establishes a 'connection' whereas the lower voltage cant get through the oxide, even though it can be just a tiny amount.
YES, cleaning the contacts might help, but i dont think i want to spray the board with contact cleaner and have it sitting inside the contacts for a while. Maybe smacking it a few times to remove the bulk of the fluid though. I'll have to give this some thought.
 
I once measured a switch that was installed in an electrical box with an ohm meter (standard 1ma or so test current) and it measured completely OPEN. However, turning the switch ON when in the lamp application caused the light to turn on normally. The voltage potential is higher for the 120vac line than for the 3v ohm meter so that is a possible explanation for that too. The higher voltage establishes a 'connection' whereas the lower voltage cant get through the oxide, even though it can be just a tiny amount.
Many years ago when checking the wiring of a newly built control system cabinet, I found that one of the mains isolator switches was open circuit when it should be closed circuit. I just replaced that switch and binned the "faulty" one.
Some weeks later it occurred to me that this could have been a "dry circuit" fault and the thing would have worked correctly with the normal mains supply instead of a multi-meter.

Ok, this problem might have something to do with the CURRENT levels we are using.
Good point, I will try and look at that later.

JimB
 
A Dry circuit is one that has very low power like a signal from a microphone. I always used gold plated contacts on switches, relays and IC sockets because they continue to work "forever" in dry circuits where silver plating is used for high current that "bites" through the black oxide that forms on silver after a while. The gold plating costs the same as silver plating.
 
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