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I'm working on a project with a few stepper motors. I want to breadboard them so I know the circuit works well before creating a physical PCB.

Each of the three motors is rated 2A, but I'll be prototyping with 1A (controled with driver chip) at 12V. How dangerous is this much current on a solderless breadboard? It's a cheap one I picked up on eBay, so I doubt that it's made with super high quality materials. I won't be leaving it plugged in for extended periods of time and it'll always be supervised with me there if it receives power. Is this a bad idea?

Note: each of the motors will be on its own rail with its own wire coming from the power source.

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    \$\begingroup\$ I would not feel happy with more than a couple of 100mA's through a solderless breadboard. Use a perfboard for the stepper drivers? \$\endgroup\$ – Wouter van Ooijen Jul 6 '14 at 9:12
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Engineers with a conscience don't let others use breadboards.

Oh, I know, it starts out easy, like any other drug. You're uncertain of yourself and instead of doing calculations, or even back of the envelope calculations you say to yourself " I'll do the easy thing, I'll breadboard it- I don't have to think too much and then I can move on". But that is the easy lie, sort of like using SPICE (but I digress) when you should be calculating \$g_m\$.

So you try it, perhaps your friends are doing it too, you want to fit in. And hey! it works, and you didn't have to spend too much time at it. But in doing so, you don't get the practise of doing those calculations, that skill never develops and eventually you end up being dependant upon the little suckers.

and then they turn on you

You're projects have started to grow, and get larger and say you want to show someone "the cool thing" you have been doing. And they want to touch it and you jump at them, not willing to allow them to touch your baby, your precious.

I was lucky when I started out. Someone gave me a breadboard to work with, and I now suspect that they did it on purpose. The thing is, this breadboard was damaged, and I wasted hours trying to get something running when it was a faulty breadboard. I didn't have that internal modelling ability, I didn't know what to expect, so I wasted time. After than once I never once used a breadboard again.

Using a breadboard is an easy way out, it's an addictive drug and if you persist you'll one day find yourself wondering " hmm, can I run One Amp those those little traces?" maybe you can. But the real question is, should you? with that much power, what happens when the board shorts out in behind (like they are wont to do)?

Listen, there are lots of ways to prototype things that take only a little more time than a breadboard that are semi-permanent, are not fragile, are smaller and more importantly allow you to build high performance circuits (be that high amperage or high frequency). Use protoboards or dead bug the circuit.

Being a little slower actually is a good thing, because you end up with something that can be handled, doesn't stop working the moment that someone sneezes and most importantly ... because you are going to put more effort into it, you learn to actually calculate before you commit. You end up learning more.

So kick the habit dead bug that sucker. You'll find that you get a better circuit by far.

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    \$\begingroup\$ 1A is probably the limit. \$\endgroup\$ – placeholder Jul 6 '14 at 1:13
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    \$\begingroup\$ Everything that @placeholder says above is true - to some extent. Judging the extent is fraught with difficulty and getting it wrong can cause endless weeping , wailing and gnashing of teeth, metaphorical or otherwise. HOWEVER breadboards, stick in the wire to connect, prototyping for the use of are absolutely marvellous. Also useful, time saving, and very productivity-improving - Except on the occasions where they are time wasting, useless and productivity-destructive. Used with care and discernment and an eye to the downside they are utterly awesome. I own untold dozens and ... \$\endgroup\$ – Russell McMahon Jul 6 '14 at 4:30
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    \$\begingroup\$ ... on past occasions have had 10 to 20 in use at once on parallel projects and used up to about 6 at a time on a single project worst case. That's a real invitation to disaster and despair and need for care increases as magnitude of components increases. | Horses for courses / everything in its place / them that dies will be the lucky ones !!! ... - oops, where did that come from. | ... \$\endgroup\$ – Russell McMahon Jul 6 '14 at 4:35
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    \$\begingroup\$ ... If you have circuitry that uses high current in one portion you can often cheat and make a flying solder wire connection to eg bring in power to the part while having a tail into the breadboard to provide signal monitoring etc. | If adding a variable quantity of 10pF to 100pF capacitors randomly to your circuit is going to cause problems a breadboard will too. | If disconnecting a random node or connection will bring fire, destruction cost or grief a breadboard may not be your friend. | They certainly have their place. \$\endgroup\$ – Russell McMahon Jul 6 '14 at 4:37
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    \$\begingroup\$ @placeholder may be right but it doesn't change the fact that he did not answer the question, which was clearly not: "Should I use breadboard?". \$\endgroup\$ – Lukasz Apr 11 '16 at 9:13
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I have been breadboarding for several years, and I keep the current through the traces below 500mA just to be safe. Anything more than that I run through separate wires. I suppose one way to check a breadboard, if you have one that is no longer any good, would be to dig out one of the metal traces and run an increasing amount of current through it until it becomes hot to the touch. Stay below that and it should be fine, but remember that only tells you about that particular board, not necessarily all breadboards. But that will put you in the ballpark regarding safe limits.

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In ref. to Breadboarding Motor Circuit. I Have Been Breadboarding Circuits for a While & In That Time, Have burned a Few. The plastic separating the Metal Channel is very Thin. As to, How much current the breadboard may take, I like to Keep It below 0.5A & that will also depend on the Voltage.

I've Learned to Keep the Current Low, while on the Breadboard. Keeping the Components that draw more Current off The Board. Using Jumpers, Perf-board.

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TLDR; Lots of boards that provide ratings say 1.5A @ 36V, but most solderless breadboards do not provide a rating. 1A @ 5V (or any 5W current/voltage combination up to 36V) is conservatively low by comparison, but will probably be safe on any random board for long periods of time.

I realize this is an old question, but here goes;

  1. Solderless breadboards are typically rated for 1A @ 5V, or 5 W. I personally would try to keep the current under 500mA @ 5V, or 2.5 W at all times. (Those power ratings are generally recommended for ~25ºC. I don't have AC in my Lab, so it gets a lot warmer in there...) 2nd hand breadboard from ebay, I would keep to 2.5 W at all times to be safe.
  2. Mildly dangerous, to Moderately dangerous if operated for long periods of time. The sporadic nature of the current through stepper motors will make it 'OK' for simple circuit testing, but potentially unsafe for long periods of time where there will be a chance of fire or a short, or both.

  3. Not a terrible idea if you want to just get your circuit tested out, or to check your firmware. Probably a bad idea if you are building a working prototype or demo unit which will be operated for long periods of time, or repeatedly for long periods of time (think how long you will spend turning it on and off while testing)

The answer which placeholder provided is also correct. =D

EDIT: Please don't take those power numbers as the amount of heat dissipated in the breadboard, they are just the amount of power that can be safely transmitted through any one trace.

2nd EDIT: I still stand by my 5W number as a good guide for boards of unknown rating, but upon further investigation, Here, and here, it seems that a boards that do provide a rating state 1.5A @ 36V. Also, the voltage I mention is not the safety rating for electrical breakdown or arching, but a 'rule of thumb' for power purposes. You can probably go all the way up to 36V with no issue on any random board, but I wouldn't bet on any random board to have enough material to not heat up running the full 1.5A.

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  • \$\begingroup\$ Where did you get the 5 V rating from? The creepage distance on a half decent board would allow many times that, I would have thought. \$\endgroup\$ – Transistor Apr 4 at 21:51
  • \$\begingroup\$ This website says a common rating is 5V@1A or 15V@1/3A ie. 5W, but my own research found the typical rating was nothing (ie. not specified). The few I could find datasheets for ranged from 36V to 500VDC. \$\endgroup\$ – Bruce Abbott Apr 4 at 23:18
  • \$\begingroup\$ @Transistor That was from my old EE lab class in college, but upon digging into some datasheets for breadboards on Digikey, I got some more concrete numbers for certain boards, but I would still keep the loads to around 5W or less for boards of unknown origin. \$\endgroup\$ – axjjienn Apr 5 at 0:17
  • \$\begingroup\$ I wouldn't call that a 5W rating, as the board itself isn't dissipating 5W unless you have a really bad breadboard! \$\endgroup\$ – Hearth Apr 5 at 0:34
  • \$\begingroup\$ Right, but giving an answer with just a current rating could lead someone to make a dangerous mistake at high voltage. The board itself does not dissipate 5W, but anything connected through any one joint should not dissipate MORE than 5W to stay safe. \$\endgroup\$ – axjjienn Apr 5 at 0:40

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