General Purpose Adjustable Power Supply

Figure 1 

The project is using a combination of an LM317 with a thumbwheel potentiometer to easily select the preset voltage outputs and set the output from 1.5V to 2V less than the input.

The basis for a quality regulated DC power supply is typically provided by the LM317 since a good adjustable power supply is essential when testing electronic projects. The input power may come from an external source while the reset voltages are 5V, 9V, and 12V. An iPod shuffle box can be used as an enclosure since the adjustable power supply fits nicely inside the clear plastic box. There is enough space for the output terminals and a potentiometer by drilling appropriate holes.

The diameters of the hole will be determined by the type of terminal posts and potentiometer to be used. The DC input jack will be provided an access by the hole on the back panel. The ventilation of LM317 and APS board which easily gets hot will be provided by a few extra holes on the sides and the cover. Good voltage adjustability is given by the precision potentiometer with 10 turns while a single turn is also preferred.

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