Review on 💡 Tripp Lite PR-3UL DC Power Supply - 3A 120V AC Input to 13.8V DC Output (UL Certified) by Tom Roberts

My PR-3UL was made in 1987, I bought it cheap at a flea market probably 10 years ago. The design is a simple inline design with a 2N3055 transistor mounted on a large rear heatsink for the final output stage, so it should be able to source a full 3A of continuous current. Internally it has one Fuse on AC low voltage side. The output voltage has dropped slightly after so many years of operation at 14V instead of 13.8V, which is not bad for all the time. There is a POT that I used to set the tension, but it was pretty tricky to set. For most people, the tension probably won't be too critical anyway. Better design and build quality than the Micronta 2.5A power supply (model 22-124) which was a popular Radio Shack competitor in the 70's and 80's. To make such power supplies larger due to the relatively low amperage with large size and weight, as well as inefficient performance. However, the output is cleaner compared to many of the smaller pulse sources commonly found today. However, for most people, a switching source is better because it's smaller, more energy efficient, and less expensive. Simply replace the existing regulator circuitry with a 78H12A and you have a stable, low-noise power supply. All that is required is a few jumpers and the placement of the regulator IC where the 2N3055 is installed.