Lone in the night

How to sort a batch of resistors? I received a batch of about 200 resistors from the E24 serie (3 bands) that I want to sort. Here is a solution for a quick sort: Make a first sort according to the multiplier coefficient This is usually the 3rd band, but maybe the 4th or 5th for the E48 or E96 series. For this value, we find the following colors: black = × 10⁰ = × 1 brown = × 10¹ = × 10 red = × 10² = × 100 orange = × 10³ = × 1000 (× 1k) yellow = × 10⁴ = × 10,000 (× 10k) green = × 10⁵ = × 100,000 (× 100k) blue = × 10⁶ = × 1,000,000 (× 1M) purple = × 10⁷ = × 10,000,000 (× 10M) gray = × 10⁸ = × 100,000,000 (× 100M) white = × 10⁹ = × 1,000,000,000 (× 1G) I ended up with 5 piles, having no value beyond 1M. Make a second sort according to the first band black = 0 brown = 1 red = 2 orange = 3 yellow = 4 green = 5 blue = 6 purple = 7 gray = 8 white = 9 Each pile was divided into 10 sub-heaps, with more or less items in each (sometimes...

Repairing a symmetric regulated power supply A great find on the sidewalk I was walking down the sidewalk when I came across an abandoned power supply and a bag full of components in front of an antique store. The dealer told me that the device does not work. One might wonder why he left it on the sidewalk in this case... Anyway, I grabbed the whole. (note: the pictures below were taken after the fix). On first inspection, it's a well built DIY creation. Solid folded aluminum housing, all cables tie-wrapped, voltage regulators mounted on generous heat-sinks with all the fittings. The only complain would be on the big capacitors; usually, they are glued on the PCB to avoid humming. However, we see the project was never completed, since the digital voltmeter (DVM) is not connected internally. Also, withing the components in the bag was another voltage regulator, a LM317K in a TO-3 package. First test After a more in-depth inspection (transformer, fuse,...