Old upload from my former channel, radioam232 (2009). Watch also the second video for more info. Shows a sturdy - almost non destructable - audio amplifier from 3 or 5-8 watt. In the first seconds from the video you see the schematic. The complete schematic with a description is available on the Lulu website, search for "3-7 Watt audio amplifier (TDA 1519 or 2N3055 transistors) with tone control".
LINK to description [ Ссылка ]
Lulu content = 13796927 published 2013. The leaflet also shows a loudness circuit (parallel T filter) to play music on low audio levels properly.
Important: the potmeter at the emitter from the BD 139 is 100 Ohm. You see an "X". This X is between the emitter from the first BD 139 and ground. There you must connect a 100 uF capacitor (or less, or more) to set the "bass" amplification and sound for low frequencies.
The input capacitor to the first transistor is 470 N non polar (= 0,47 uF). Important: without a series resistor from the input potentiometer to the base from the first transistor the amp can start to oscillate (!). Watch the second video or download the schematic via Lulu for more info.
The diodes in a row between the two bases of the driver transistors are all 1N4007. Glue these 3 diodes to the heatsink, they have to make a thermal contact with the 2N3055 heatsink in the upper part of the schematic. Mount all transistors on separate (!) heatsinks, both the drivers (!) and the end transistors or download the schematic at Lulu for precise information. If you have questions about the circuit mail me on radiofun232@gmail. com. The amplifier has a good sound, I do not know whether it is Hi Fi. Of course good loudspeaker boxes are necessary.
Much more audio audio in my book "Schematics 2, audio amplifiers and loudspeaker boxes" on the LULU website, author Ko Tilman.
This book is also illegal available via "Cloudflare" (San Fransisco) and "myfreemediacloud" (Russian website) but when you download it there it contains a virus or malware. Cloudflare San Fransico helps to make stolen content available on the internet. I did not receive any reaction from Cloudflare on my written complaint regarding this issue (september-oktober 2015).
