Im using a Lucky Sky S-50-5 switching power supply to externally power an Arduino UNO, connecting the positive and negative to the Vin and Ground of the Arduino, respectively. Though, at shorter wire length it powers the arduino just fine, but since in this project the arduino is encased inside a boxed, the wire length increases significantly. By the time it reaches the arduino, the voltage drops at approximately 0.7~0.8 V at the load. What can i do to maintain a constant 5V voltage at the board?
Minimum for Vin is 6.5~7V.
With a 5V power supply you should connect positive to 5V pin on the Uno.
From the maker of the UNO:
5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
Ignoring the other issues, if you're suffering from voltage drop over long wires, you can do two things.
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increase the wire sizes. For every 3 AWG decrease, you double the wire cross section, halving the series resistance of the wire per unit length. Thus, going from 20 ga to 14 ga, you reduce your voltage drop by a factor of 4. (this is a ROT, approximately true, for those who will immediately quibble about the second decimal place of the savings). An alternative work-around for testing may be to simply run two wires of the same gauge for each power wire; ensure that they are firmly connected at both ends, or the savings will be compromised.
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reduce the current demands at the far end of the wire. That means no unnecessary LEDs, use an Arduino with a low power demand, minimize accessories, maximize resistances for display LEDs, status LEDs blink instead of constantly on, etc. etc..
Hi, @saad2715
Can we please have a circuit diagram?
An image of a hand drawn schematic will be fine, include ALL power supplies, component names and pin labels.
Thanks.. Tom..
How long are the wires?
What gauge is the wire?
Is there anything being powered along with the Arduino (increasing total current)?
Wire Gauge Chart (Ohm's per 1000 feet, etc.)
Ohm's Law (For calculating the voltage drop across a known resistance when the current is known.) Remember that the total wire length is twice the distance with the current flowing through the "complete circuit" back to the power supply.
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