A small tour inside my “laboratory” hobby power supply (0-35 V- 3 Ampère) and schematic

A small tour inside my power supply (0-35 Volt, max 4 A) and some tips to make a good quality power supply that will last for decades in your laboratory or hobby room..

Next video is here: https://youtu.be/JXf9evXhUW8

Important features: a separate AC output, a current limiting resistor-bank, fuses on critical places in the circuit, the (minimal value) 4700 uF supply capacitor, protection against HF stray frequencies and a sturdy series regulator made with a BD 139-2N3055 on a good heatsink (corresponding video’s are on my YT channel).

e.g. here: https://youtu.be/AwWQWghTSpo
and here: https://youtu.be/FrT395Nf6HI
also in my book “Schematics 1″(page 55), you can buy it via the Lulu website
and: https://youtu.be/YL41FPH_H-s

Also important: a digital voltmeter (preferred precision 1/100 of a Volt) and a variable (!) output Voltage, going from 0 (zero) to anywhere (practical here is max. 40 Volt DC, given the BD139-2N3055 Darlington that is used, it cannot handle more power, a good quality 2N3055 (Hfe 50-70, test the Hfe first, combined with a BD 139 with a Hfe of 150) can handle maximum 2 Amp on 40 Volt = 80 Watt constantly on a big heatsink).

Always “switch in” during work with this power supply a series resistor (power types) of (say) 2 or 5 Ohms to have a kind of shortcut protection when you make mistakes/do tests in (developing) electronic circuits.

I always have the 2 Ohm or 5 Ohm power resistor switched in.

Test your power supply by switching in an appropriate series-resistor (from the resistor bank) that will give the nominal current for which your transformer was rated (study the datasheet of your transformer) and shortcut the output and/or connect to the output (say) a few halogen lamps to get to that nominal transformer current.

See how long your circuit can handle this endurance test situation, say half an hour is good, it will get very hot but must not break down.

Circuit is also on page 62 of my book: “Schematics 1, revised” available on the LULU website. Search for Ko tilman there. And there is a free download on the LULU website of this schematic, say for max. 25 Volt.

All the videos hat I have published on You Tube can be found via my Channel Trailer: Link is

In thematic order you can find these video’s under the “comments” section.

Important: to find all the links to the (+/-700) video’s on my YT Channel, select, in the comments section, “NEWEST FIRST”

My books about electronics are available via the website from “Lulu”, search for author “Ko Tilman” there.

There is an important video via which you can buy a document where I give links to many of my video’s, published between 2010 and 2018.

Link is: https://youtu.be/XXRsA24NUE0

My books are also available via Barnes and Noble and via Amazon.

Regarding all my video’s: I constantly keep them actual, so the original video’s with the most recent information are always on YouTube. That is the source, and search there. When my video’s are reproduced or re-edited on other websites/channels you can not (!) be sure about the original content (=really working electronics) and important adaptations to the circuits. Be aware of that, I saw on the internet some of my circuits reproduced in a poor or even not proper way. I can not help that, sorry. Upload 1 january 2019.