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Mini audio amplifier approx. 30-50 mW, works on 3 Volts or even a lower voltage: schematic/demo/info



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Please read the textbox. A (mini) 30-50 mW audio amplifier on 3 Volt or even lower voltages. The video tells everything: properties, battery use, critical components, probable distortion and how to cure it. Music: "the day is close", by the 126ers, copyright free music. They made many songs usable for demo purposes, but also easy listening. Sounds good.

Do experiments with the value of the 10 K resistor and the value of the capacitor that goes from the base of transistor 1 (BC 547 b) to the “null” = “zero” node, where the electrodes of both 1.5 Volt batteries meet.

IMPORTANT: circuit is made for battery use and is experimental, not made for beginners in electronics. Don’t connect your MP3 player or audio Smartphone output (headphone output) directly to the “node” = the “zero” wire in the electronic circuit where the + of one 1.5 battery and the – of the other 1.5 battery meet and are connected.

That can damage your MP3 player or smartphone, by adding approx. 1.5 Voltage to the headphone output of the MP3 player or smartphone.

Use that 100 N separation capacitor (in the schematic, properly explained!) and connect everything like it is showed in the schematic. This is a disclaimer.

NB: my MP3 player did not get defective when I made this faulty connection, but stopped and showed irrational behaviour (switching in/out in a random way, etc).

The mentioned capacitor that makes the input of transistor 1 “quiet” is 100 N (=0,1 uF) but you can do experiments. The circuit works and was made for 3 Volt. It was tested and after approx. 15 hours of continuous use it still worked properly without problems, voltage dropped to 2 x 1.27 volt. Started with 2 batteries of 1.5 V each, that were not completely fresh.

Don’t expect too much audio quality, compare the sound of this amplifier to a standard cheap small MW radio. Most important thing is that it must be able to work with 2 x a 1.5 Volt battery (=3 V) for x hours. The transistors (BC 547 b NPN and the BC 556 b PNP) need no cooling, they don’t get warm.

There are more than 1200 Video’s on my YT channel. I only do analog electronics: audio amplifiers, and much more.

When you have questions about (certain analog) electronic circuits and how to make them: go to my Channel trailer (Radiofun232 on You Tube) and go to the “looking glass”. Type there the keywords that you want/need like: “power supply”, audio amplifier, capacitor tester, oscillator, radio, shortwave, shortwave radio, or any keyword you like to find the essential info & schematics on my YT channel.

You can contact me via email when you have questions about my published circuits. I always ask for a picture of what you have made + a problem description; I ask to communicate. When you don’t want to give information/communicate please don’t ask help. Sorry that I am so strict now (since 15 may 2021). It has to do with disappointing reactions in the recent past of people that asked “help” (even fake help) and did not react afterwards or asked questions when they knew the answer.

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You can also search via the “looking glass” on my Channel trailer via keywords like ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in. My books about electronics & analog radio technology are available via the website of "LULU”, search for author “Ko Tilman” there.
https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=Ko+Tilman

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Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 22 september 2021.
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Audio
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