Every home laboratory needs a power supply with adjustable voltage and current for the implementation and testing of prototypes and custom projects, or for repairs. Of course, such devices are commonly available for purchase in electronic component and measuring instrument stores.
The presented design of the laboratory source differs somewhat from the common concepts of such devices.
The enormous development of electronics over the past decades has also affected our homes. The term Smart Home is no longer a stranger to anyone. Home Assistant undoubtedly has its place among the various Smart Home systems. 
One of the important devices in the production of printed circuit boards by the photo process is the exposure unit. Its construction, for radio amateur needs, is described in this article.
