That’s why all our products-including USB power adapters-undergo rigorous testing for safety and reliability and are designed to meet government safety standards around the world.Īs part of our efforts to reach our environmental goals, iPhone models no longer include a power adapter in the box. Since 19V is so close (+6%) to 18v, this should prevent damage to the sign as it is unlikely that any components used would fail at 19v with minimal current, but I would NOT recommend a similar approach id you were using, for example, a 24v source, since the significantly higher voltage could blow capacitors, transistors, diodes, etc in the sign that may not be spec'd to withstand that voltage.Customer safety is a top priority at Apple. NOTE: The resistor will not stop the light from "seeing" move than the expected 18v supply, but it will limit the voltage/current to the sign down to 18V/2A at the maximum-power point. To come up with this, dividing the sign's required current (2A) by its required voltage (18V) yields an expected load resistance of 9ohms to get the same 2A current from a 19V source requires a resistance of 9.5ohms then, accounting for a 1V drop across you 0.5ohm resistor at 2A, we see that the resistor should regularly be dissipating 2W of power, so must make sure its rating is sufficiently above 2W to insure against damage yielding the 0.5ohm 5-10 watt resistor (cheaply available in a ceramic potted wire-wound type). However, if you want to be more cautious with it, then you could add your own highly stable voltage regulator (a great reference for this can be found at: ) or, for a "quick and dirty" approach, you could try simply adding a 5w or 10w 0.5ohm resistor inline between the adaptor and the sign. Now, for usage, the LED sign very likely (but not guaranteed) has an internal voltage regulator, in which case, the small (about 6%) overvoltage would be handled there. TLDR, don't try using this adapter unless you are willing to risk damaging your device from the extra current.įirst off, that symbol on the laptop pwr adaptor simply means that its output is DC current (as opposed to AC mains power). Whether this difference is significant enough to destroy your LED sign is a matter of how much tolerance was built into it the 1-volt increase may merely increase the brightness of the LEDs or burn them, if 19 V is outside the device's range, or have no noticeable effect at all (if the 19 V is being stepped down further within the device). However, the laptop adapter's voltage is a full volt above the specified 18 V this will cause more current to flow into your device, since the voltage has been increased. Any device will only draw as much current as it needs, so long as its power source can supply it. This doesn't mean your device will consume 3.42 A when its powered with this adapter it is only an indication of the maximum current that can be drawn through the adapter by any device that it is connected to, above which the adapter gets damaged. This laptop adapter supplies an output voltage of 19 V and a maximum output current of 3.42 A, well above your original adapter's 2A maximum. The weird symbol indicates its a DC output.
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