solderless breadboards: passing current through the contacts

[eccerr0r]

Well, we know that contacts and connectors can be quite resistive, but wondering for those of you who have worked with DIP/IC breadboards, how much current have you passed through the contacts without it failing? I have seen spec sheets saying 1A or possibly even 2A is fine but wow... will it really handle a few amperes through those beady holes without enough drop to make your circuit fail? Personally I think more than a couple hundred milliamps it'll heat up and break it...

I suppose the bus bars for supplying power need it most, but experimenting with building power supplies on these boards would require some thought...

[Kiriakos GR]

Re: solderless breadboards: passing current through the contacts

I did ordered my first breadboard before three days ago, and it has clear acrylic plastic on the top, that is a special version for noobs of some age. LOL

Heat and sparks can caused when the contacts in those holes are not stiff as when it was new.
And regarding designing an analog circuitry for a power supply, on the breadboard you will going to have just the driver circuitry (control circuitry) and your 2N3055 over a heat sink.
Therefore I do not see any problem.

[eccerr0r]

Re: solderless breadboards: passing current through the contacts

Well, if one was doing a series-pass PSU then yes that 2N3055 wouldn't fit regardless, but if one was trying to build, say, a slightly upped MC34063 circuit. Perhaps a 2A with an external switch and (obviously) inductor, but many parts of the circuit would need to pass a fairly large amount of current.

I've never had one of those transparent plastic solderless breadboards before, all of the boards I have are translucent. I really wonder how bad the diffraction through the plastic would hurt plugging things into the right hole though...

[momaka]

Re: solderless breadboards: passing current through the contacts

IIRC, I tried passing 3 or 4 Amps sustained through mine, and it hasn't been damaged yet.
Some of my projects regularly pass around 1A of current through contacts. I think up to 2 to 3 Amps should be fine.

[JonathanAnon]

Re: solderless breadboards: passing current through the contacts

I was asking myself this question only a week ago, when I was wondering what to test a mains circuit on... I looked up the spec for my solderless breadboard and it said 1A as well..

edit: sorry ^ meant 1 amp not 1 milliamp..

[momaka]

Re: solderless breadboards: passing current through the contacts

I wouldn't put any mains voltages on those breadboards. Not sure how good their insulation is and at what voltage they may arc over. The highest I've tried was 50 or 60 VDC. Also built an RCD snubber network on my breadboard for a transformer winding. The kickback was producing around 120 VAC. Don't know if the board was arcing over or not, though.

[senz_90]

Re: solderless breadboards: passing current through the contacts

i have tried to build transformerless psu on my breadboard a long time ago. i didn't know exactly what current flow through it but, when i forget to add 2W resistor, my breadboard burned with that resistor. i was surprised and get it off from mains quickly.not too bad, just a little burned on 1 line. but it has a dark yellow mark to makes me remember always keep the current as low as possible on breadboard, maybe below 1.5 A. not sure exactly. LOL

[JonathanAnon]

Re: solderless breadboards: passing current through the contacts

I wouldn't put any mains voltages on those breadboards.

I've had one melt completely when a very small audio amplifier chip overheat, so I would agree.. This also got me questioning what current those small stripboards can take..

Hey eccerr0r, why dont you carry out the test and youtube it .. 1A for ten minutes, 2 amp for ten minutes.... See how far it goes..

[kaboom]

Re: solderless breadboards: passing current through the contacts

They'll also burn good.

Had a 3843 explode when a MOSFET shorted and backfed raw DC. There was a little flame around the '43 til I shut off the seperate exiter power supply.

[goontron]

Re: solderless breadboards: passing current through the contacts

i have burnt one before, it wasn't amps but volts 2kv to be precise.

[Kiriakos GR]

Re: solderless breadboards: passing current through the contacts

I bet that there is out there hundreds examples of heroism which send to grave a simple breadboard.

But the safe limit of misuse could be the most power hungry LM78XX that is close to 1A.
But even so you should expect a temperature of 65 Celsius with huge heat sink so to get this performance, or else it would run close to 100C.

What I am not aware is the ultimate temperature that those breadboards can handle.

[tom66]

Re: solderless breadboards: passing current through the contacts

A burning 1/4W resistor permanently melted a breadboard of mine, but it was still usable, just sticky.

[momaka]

Re: solderless breadboards: passing current through the contacts

What I am not aware is the ultimate temperature that those breadboards can handle.

Exactly my point.

Breadboards can usually handle a fairly high current, but when components start running hot, they also end up heating the breaboard too. And that's when contacts can get loose and start arcing/rapidly overheating.

Also, most burn marks I've seen on breadboards aren't from melted contacts or over-current but rather from frying a component (usually the designer's fault).

[eccerr0r]

Re: solderless breadboards: passing current through the contacts

I guess if you skip columns you can get some voltage insulation - I was breadboarding that boost PSU, and got around 380V so far and it hasn't arced over yet (I think, at least I don't see or hear it). The voltage drop across a neon bulb seems to do fine on the breadboard at least, I fed the 380V through a 1Mohm resistor to a neon bulb which lit just fine.

I do wonder how good the insulation is on my wire - the breadboarding wire I'm using is the same I've been using for low voltage digital circuits.

[mariushm]

Re: solderless breadboards: passing current through the contacts

Well, if one was doing a series-pass PSU then yes that 2N3055 wouldn't fit regardless, but if one was trying to build, say, a slightly upped MC34063 circuit. Perhaps a 2A with an external switch and (obviously) inductor, but many parts of the circuit would need to pass a fairly large amount of current.

I'd just like to make an observation.

MC34063 is pretty much a horrible switching regulator, it's cheap and there are online calculators out there which help you figure out the components, but otherwise it's really a lousy IC which lacks some of the protections other chips have nowadays.

Also, in general, switching regulators don't work well with breadboards. Inductor has to be very close to the pin of the IC, same with some resistors, the breadboard just complicates things.
MC34063 is not quite that high frequency that it would matter, it can be prototyped on a breadboard, but if you do some measurements and then transplant it to a veroboard/stripboard or proper pcb, you'll see other values in the new measurements. So just be careful about that.

I do wonder how good the insulation is on my wire - the breadboarding wire I'm using is the same I've been using for low voltage digital circuits.

Hmm... breadboarding wire. That's usually AWG 22-24... should be a no-brainer to just look up that kind of wire on Digikey and see the typical insulation for that wire.
I would guess they're safe for about 100v and about 1A, considering the AWG gauge and length of wire.

[LDSisHere]

Re: solderless breadboards: passing current through the contacts

I was wanting to find a short on the 5V section of a motherboard and I thought the best way to do this was to use a lot of current to heat up the bad part. I wired nine 1 ohm resistors in parallel and connected the 5V of a modified ATX supply to provide power.

As you can see in the picture I was trying my best to blow the fuse in my meter as I put over 15A through the breadboard and meter. I know it is low voltage but that is still a lot of current.

[retiredcaps]

Re: solderless breadboards: passing current through the contacts

As you can see in the picture I was trying my best to blow the fuse in my meter as I put over 15A through the breadboard and meter.

The 175 can do 20 A overload for 30 seconds maximum and then requires 10 minutes of rest minimum.

[LDSisHere]

Re: solderless breadboards: passing current through the contacts

The 175 can do 20 A overload for 30 seconds maximum and then requires 10 minutes of rest minimum.

Thank you for that information as I did not realize it could do that. I guess I was not the fuse daredevil that I thought I was being

[retiredcaps]

Re: solderless breadboards: passing current through the contacts

Thank you for that information as I did not realize it could do that. I guess I was not the fuse daredevil that I thought I was being

At $10 a pop, I don't take any chances.

I did buy some cheap generic 50 cent 10x38mm 10A ceramic fuses, but I haven't tested them yet. I may put them in one or two multimeters where I know I will only use them on low powered circuits.

[ben7]

Re: solderless breadboards: passing current through the contacts

IIRC, I tried passing 3 or 4 Amps sustained through mine, and it hasn't been damaged yet.
Some of my projects regularly pass around 1A of current through contacts. I think up to 2 to 3 Amps should be fine.

Yep, I've done nearly 5 amps for maybe 30 minutes, the breadboard was only slightly warm, then again, it likey was some of the heat from the circuit itself...

I've had one melt completely when a very small audio amplifier chip overheat, so I would agree..

And, that is how I learned not to overload IC's.
My first 555 circuit, I fried the 555 after overloading it's output. It get VERY hot and melted the breadboard...