Max current for a stripboard?

Thread Starter

Strahan

Joined Nov 25, 2018
10
Hello. I got your help recently on building a circuit to replace batteries in a towel dispenser. It works, but the motor runs as if it was using tired batteries. I thought it was the USB charger that I was using not putting out enough power so I bought a Leviton 2 port USB charging power outlet. It's rated 3.6 amps shared, so I guess that means 1.8 amps per port. The little box I was using before was 2.1 amps shared so I was hoping more available amperage would translate to faster operation.

I just installed the new outlet and it's no better. Then it hit me; the wire I was using to go from the USB female port to the circuit board is 24 gauge. That's probably choking off the power, right? I read that 24 gauge is only good for half an amp. So for better performance (and less fires lol) I figured I'd go with 18 gauge. My stripboard though has very tiny holes. I figured I'd drill the hole to make it wider but then I got to wondering how much current the traces between holes is rated for. Will I just be moving the bottleneck from the wire to the traces?

Would I be better off getting one of those copper clad boards and doing the print transfer / ferric something-or-other bath method to make a custom board or am I just imagining problems where there won't be any?

Also I figured I need to swap my IN4001s for 1N5400 as the latter goes up to 3 amps vs the former's 1. Will that still work the same to step down the voltage or will that change that aspect as well?
 

MaxHeadRoom

Joined Jul 18, 2013
20,878
Standard Vero board should be good for at least 2a to 3a, what I do is lay/solder a conductor along any strip that may be carrying at or over rated current.
Solid conductor or Dry-Wick is good.
Max.
 

Hymie

Joined Mar 30, 2018
835
I would suggest you short out one of the diodes dropping the voltage to the motor – this will increase the motor supply voltage to around 4.3V (and will compensate for losses in the connection path to the motor).

You might consider changing the diode for one of a higher current rating, but if used intermittently, the 1A rating should be sufficient for a draw of over 2A.
 

ebp

Joined Feb 8, 2018
2,332
Current ratings of all sorts of things are often quite unhelpful when dealing with low-voltage circuitry, other than to keep things from melting. At 50 V, at drop of half a volt across a resistance might be completely acceptable, but at 5 V it is a big loss. The conductor won't run any hotter with the 50 V circuit than with the 5 V circuit, and temperature rise is usually how current ratings are arrived at, whether it is a piece of wire, a FET, a diode or a switch contact.

Actually measuring voltage drops can be helpful. With your application, it may be hard to get a stable meter reading in the time the motor is running. If you can identify a path with "too much" voltage drop, then you can beef it up with wire as Max suggested.

Some multimeters allow you to make quite good measurements of low resistance, but most are mediocre for this. Typically when you short the leads together at the tips, you'll see a resistance of something around a tenth to a fifth of an ohm - and on the least significant digit of the meter. This makes it nearly impossible to measure low resistance accurately. High-end meters support a 4-lead ("Kelvin") connection that applies the test current with one pair of leads and measures the voltage drop with another. Some less expensive meters have features that can be helpful, such as setting the display to read zero when the probe tips are shorted (i.e. short the tips & press a button to "null" the lead resistance).
 
Top