Step-Down Converters & Voltage Regulators
Many owners of Longer 3D printers love to customize the machine with additional accessories, LED lighting, and so on. However, each accessory works at a specific electrical voltage and requires a certain current, so attention should be paid to the technical specifications of each of them; in fact, Longer printers generally work at 24V, so it is not enough to simply connect the accessories to the mainboard of the printer or to its power supply, since this could compromise the operation of both the printer and the accessories.
NOTE: This guide is only for an electronically savvy audience! Misinterpretations could cause accidents and damage to equipment. If you don't feel confident, don't try the changes but talk to an expert.
In order to lower the voltage from 24V to a lower one it is necessary to cause a "Potential Difference Drop". The most basic method in physics to achieve this is the use of a resistor, however it dissipates all the current absorbed in the form of heat, so it is an inefficient and unstable method, since it depends on many factors. Nowadays there are various electronic components that can perform this function in an excellent way, and given their really low cost it is really worth considering to be able to operate safely. Here is a description of the best components on the market.
XH-M401
This voltage converter allows you to adjust the potential difference downwards efficiently and supports a high current passage thanks to the presence of two power mosfets. Connected to one of the outputs of the printer's power supply, it allows you to adjust the voltage between 24V ~1V, so it is ideal for connecting 12V & 5V LED lamps that require high current absorption, to connect 12V & 5V fans, to connect camcorders that require a specific voltage, or any other type of accessory.
L7812
This linear voltage regulator allows you to adjust a voltage of 35V max in a voltage of 12V output, however the output current is 1A max and also dissipates in the form of heat; for this reason, the voltage regulator has a hole, as it must be fixed with a screw on top of an aluminum bracket in order to reduce its temperature. Using this regulator, it is possible to reduce the voltage from 24V to 12V, however its use is limited to accessories that require a very low current (for example, a 12V fan), and in any case the regulator must be dissipated by fixing it to the printer frame taking care not to cause short circuits.
L7805
This linear voltage regulator, similar to the L7812 regulator, allows you to reduce the voltage by having a 5V output. It is often used to reduce voltages of 12V towards 5V, however it can also be used to reduce the 24V of the machine in 5V even if the dissipation in the form of heat will be really excessive. It is strongly discouraged to use this voltage regulator allows, preferring in its place the XH-M401 regulator.
SZBK07 300W/20A (for special applications)
This voltage converter can be too elaborate, as it allows both to adjust the output voltage and to limit the max current absorbed by the connected component in output. This turns out to be the best compromise to power driver-free LEDs, battery charging and other applications that require special attention. It is exposed here only for information, as accessories for 3D printers do not require such precautions.
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