Electronics > Beginners
What's best way to reduce a voltage... (picture)
rsjsouza:
--- Quote from: Gyro on March 14, 2019, 02:34:55 pm ---A series chain of 5 diodes would drop about 3 - 3.5V. You just need to ensure that your protective device (low rated fuse or PTC thermistor) is the FIRST thing at the positive terminal of the PSU. Insulate the diodes in a length of heat shrink.
--- End quote ---
Just be sure you are using Silicon Diodes, which drop about 0.6V per diode, and not Schottky, which drop about 0.2V per diode. Visually they are very similar, thus it is important to pay close attention to its part number.
The most common Silicon Diodes that are suitable for this task are from the 1N400x family (1N4001, 1N4002, etc.)
mariush:
Your Arduino most likely has a linear regulator on the circuit board that converts the input voltage (on the DC jack) from 9v to 5v.
That linear regulator most likely supports voltages up to 15v or 20v or some higher voltage than 9v, they simply say 9v because it's a very popular/common voltage for DC adapters, so such adapters can be easily bought.
For example, a very common linear regulator is *1117 (* because it's made by lots of companies so first 1-3 letters represent the company who makes it) ... here's LM1117 : http://www.ti.com/lit/ds/symlink/lm1117.pdf
If you can scroll in the datasheet, you will see the maximum input voltage recommended is 15v, so if your Arduino board has one of these, you can safely power it with 12v.
Now, it's important to keep in mind that the more difference is between the input voltage and the output voltage of a regulator, the more that linear regulator will heat. So for example, if your Arduino board consumes 100mA of energy, then at 9v input, your regulator will produce (9v-5v) x 0.1A = 0.4 watts of heat, but with 12v input, that value changes to 0.7w which is a bit higher but still reasonable.
For a few leds on your Arduino board, a lcd display, basically if your power consumption is quite small (you can measure by placing a multimeter on current range in series with the input) and the linear regulator on the board supports more than 12v, then you could power with 12v.
If you can't tell what regulator you have on your Arduino board, take some clear pictures of your Arduino and post them here and we may be able to help you out.
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