Voltage Drop at Breadboard

[anbudroid]

Hello Everyone ..

      I Have a Chinese Bench power supply set its voltage to 7.5V send it Directly to DC-DC step Down Module Mounted in a breadboard. The output voltage of 5.07 from DC-DC Connected to Arduino nano and 1602 LCD. but after connection the voltage drop to 4.68. I remove the bread board and jumper cable and solder everything together then the voltage at arduiono 5V input is 5.04 . what cause this problem? I swap my old breadboard with new one but problem not solved .

       Am new to this forum. Searching internet for 3 days about voltage drop in breadboard and didn't find any result regarding this topic . so I thought this only happen to me. this is my second college project of my brother  I plan to help him in his electronic side. so I bought some breadboards , jumper cables and few op amps to play around little bit before we start . we both are not have much knowledge in electronics.

[mycroft]

Many DC/DC converters requires a minimum load to satisfy the output voltage specification. See https://power.murata.com/datasheet?/data/power/ncl/kdc_cre1.pdf. The no load voltage can be much (>20%) higher.

[tggzzz]

The problem is that you are using solderless breadboards. Inevitably you will spend more time debugging the breadboard than the circuit, due to variable and varying stray resistance, capacitance and inductance.

It is much easier to copy the masters, and use manhattan techniques or rat's nest techniques.

[Ian.M]

Anyone working with Arduinos with female headers, or solderless breadboards etc. nneeds to be aware there's a lot of cheap and nasty flexible jumper cables with Dupont pin ends out there that are defective.

Common defects are: the stranded wire used is far too thin;  it isn't even copper wire; the ends aren't properly crimped; the wire has broken internally.    In all cases the resistance of the jumper will be excessive and if you draw a significant current through it you'll get a large voltage drop.   

Check the jumpers resistance before use after straightening it out and tugging gently on its ends to see if the crimps are loose or the wire's broken.  If it feels springy when you try to straighten it, or  stretchy when you tug the ends, breaks, or the resistance reads more than a fraction of an ohm over the reading you get with the test probes touching each other, discard that jumper. 

If you have more than one that are high resistance you can investigate further by stripping the wire and observing if its too thin, or if the wire is attracted to a magnet (copper coated steel), or fails the flame test (copper coated aluminum).

N.B the flame needs to be yellow as show, not a fully oxygenated blue blowtorch style flame as that can (just) reach the melting point of copper.

[Doctorandus_P]

How much current is your LCD pulling out of the power supply?
4- line displays may go upto 100mA, maybe 200mA.
That would be:
U = I * R  =>
R = U / I =>
R = 200mV / 200mA = 1 Ohm.

This seems excessive.
The cheap Dupont wires from China often have a relaltively high resitance (usable for signal wires, but be carefull for power supplies)

Another possibility is your electronics boards drawing high current peaks, which result in short voltage dips, which get averaged by your DMM.
You can try distributing a few ceramic 100nF caps over the horizontal breadboard power distribution bar and add a fairly large buffer elco (100uF or so) to the right of the breadboard.

[Audioguru]

The contacts that grab wires on a Cheap Chinese solderless breadboard are dirty or corroded and make poor connections.

[IanB]

I Have a Chinese Bench power supply set its voltage to 7.5V send it Directly to DC-DC step Down Module Mounted in a breadboard. The output voltage of 5.07 from DC-DC Connected to Arduino nano and 1602 LCD. but after connection the voltage drop to 4.68. I remove the bread board and jumper cable and solder everything together then the voltage at arduiono 5V input is 5.04 . what cause this problem? I swap my old breadboard with new one but problem not solved.

As others have said, the problem is excessive resistance in the jumper wires, the wire/breadboard contacts, or the breadboard itself (or a combination of all three).

But is there any reason you don't set the bench power supply to 5 V and use it directly to power the modules?

[IanB]

The problem is that you are using solderless breadboards. Inevitably you will spend more time debugging the breadboard than the circuit, due to variable and varying stray resistance, capacitance and inductance.

It is much easier to copy the masters, and use manhattan techniques or rat's nest techniques.

Wow, pessimist much?

People have built whole working microcomputers on solderless breadboards with hundreds of jumpers. For simple, basic circuits breadboards are not that terrible.

[anbudroid]

am using single stead cable . but from scrap. I try with new one sir. I realise pre made jumper cable's are too thin and failed to conduct more current. is there any link for good quality cable ? ali express links is better for me to get 

[anbudroid]

I tested without DC-DC too sir. I use DC DC because my brothers project interface with 12V system.

[anbudroid]

Total Current Consumed by the LCD and Arduino Board is just 120mA . am not using prebuild breadboard cables I know they were not quality products so that I use single stead 22AWG Cable for BreadBoard

[Jwillis]

Using those cheap bread boards is fine.They work just as well as the expensive ones. Check that you have enough supplied current .

[metrologist]

I have ten breadboards and I've been using a spool of old school solid copper 4 conductor phone line to make jumpers. It is a little thin but solid copper and cheap.

Some of Arduino clone regulators are weak, if you are using that. I get low voltage.

[anbudroid]

I have ten breadboards and I've been using a spool of old school solid copper 4 conductor phone line to make jumpers. It is a little thin but solid copper and cheap.

Some of Arduino clone regulators are weak, if you are using that. I get low voltage.

Yes Sir. My bench power supply current is 1A . But the circuit Just need below 200mA . and at this point total current consumption of the circuit including LCD is 150mA from Bench PSU.

[anbudroid]

I have ten breadboards and I've been using a spool of old school solid copper 4 conductor phone line to make jumpers. It is a little thin but solid copper and cheap.

Some of Arduino clone regulators are weak, if you are using that. I get low voltage.

Am not trust Arduino's inbuilt passive regulator. that's why am using separate DC-DC Buck Convertor. I tried with phone line cable too just now.

alternatively give 12v to bread board and connect a load to other half side of the breadboard voltage drop is 400mV . so nominal resistance of my bread board accourding to ohms law is 0.2ohms. is this correct ? total current by the load is 500mA

[tggzzz]

The problem is that you are using solderless breadboards. Inevitably you will spend more time debugging the breadboard than the circuit, due to variable and varying stray resistance, capacitance and inductance.

It is much easier to copy the masters, and use manhattan techniques or rat's nest techniques.

Wow, pessimist much?

Long experience, both mine and others. That probably means there's more realism than pessimism. Start by considering this thread, and look closely at the useful pictures the OP supplied!

People have built whole working microcomputers on solderless breadboards with hundreds of jumpers. For simple, basic circuits breadboards are not that terrible.

...and then somebody sneezed.

You can go over the Alps/Rockies/Himalaya on a push bike - many people have done all of those. But expect to have to spend a lot of time fixing problems with the bike

[tggzzz]

am using single stead cable . but from scrap. I try with new one sir. I realise pre made jumper cable's are too thin and failed to conduct more current. is there any link for good quality cable ? ali express links is better for me to get

Even if you have good wires, you still have the problem of getting a good and reliable contact.

[tggzzz]

Using those cheap bread boards is fine.They work just as well as the expensive ones.

I disagree with the first sentence, but agree with the second.

[windsmurf]

You might try multiple jumper cables for each connection to reduce resistance, if poor cable is the issue.

[tooki]

Using those cheap bread boards is fine.They work just as well as the expensive ones. Check that you have enough supplied current .

I'm the opposite of tggzzz: I disagree with both sentences.

Some cheap breadboards are fine, but others are awful. I've got some cheap ones that have several ohms contact resistance, which absolutely makes itself known in many circuits. Better cheap ones are sub-ohm, and top-quality ones just in the mOhms.

Given the issue of voltage drop here, I'd suspect that it's a cheap breadboard and contact resistance is adding up.

[Audioguru]

I gave up using solderless breadboards many years ago. Then I used stripboard with everything soldered and had no problems. The stripboards were neat and tidy with no messy tangled pile of wires all over the place and the strips of copper cut to length and a few short jumper wires formed the wiring of a pcb. If a part needed to be replaced then my solder sucker easily removed it. Most of my circuit designs were for audio or communications and were custom so only one or two needed to be made. My stripboards looked so neat and tidy that my prototype was usually sold as the finished product. Some were very complicated with many parts.

[tggzzz]

Using those cheap bread boards is fine.They work just as well as the expensive ones. Check that you have enough supplied current .

I'm the opposite of tggzzz: I disagree with both sentences.

Some cheap breadboards are fine, but others are awful. I've got some cheap ones that have several ohms contact resistance, which absolutely makes itself known in many circuits. Better cheap ones are sub-ohm, and top-quality ones just in the mOhms.

Given the issue of voltage drop here, I'd suspect that it's a cheap breadboard and contact resistance is adding up.

Just so

My agreement with the second sentence was a subtle dig at breadboards because of what I omitted to say. My longtime experience is that both cheap and expensive solderless breadboards are an unnecessary and unacceptable waste of time!

[tooki]

Breadboards may be categorically unsuited to some types of circuits, but they're of incredible value to beginners especially. There's a TON of value in being able to quickly lash together a circuit and play around. It takes far longer to solder something together, and making changes are even harder still. I think you guys forget that breadboards are, above anything else, a learning tool — you guys are experienced and knowledgeable, but for those of us still figuring things out, breadboards are incredibly useful.

Just don't buy cheap!

[tggzzz]

Breadboards may be categorically unsuited to some types of circuits, but they're of incredible value to beginners especially. There's a TON of value in being able to quickly lash together a circuit and play around. It takes far longer to solder something together, and making changes are even harder still. I think you guys forget that breadboards are, above anything else, a learning tool — you guys are experienced and knowledgeable, but for those of us still figuring things out, breadboards are incredibly useful.

True, they are a good way to learn about unexpected extra "components", and how to debug imperfect implementations (cf designs).

[Zero999]

I'm not convinced the breadboard is this issue in this case. Whenever anyone mentions breadboard, there's always this discussion which is valid, but is also a distraction.

I'm more suspicions of the DC:DC converter.

anbudroid,
Did you measure the voltage directly at the DC:DC converter's input and output terminals on the board?