The IC-TDA2009 amplifier circuit on stereo 10W+10W IC is to qualify from the power supply 8-24V, the current maximum of 1-2A. and 24V load 4 ohms [...]
No light! because of a low voltage battery. How do you increase the voltage up? You can do many ways. And, I recommend a simple step-up converter circuit using TDA2822.
I like the 12V LED. But I have only 3V of batteries. So, No light. When using this circuit, I can get light of the LED at 100 mA. And, an adjustable output voltage.
Relatively easy to build up to 30W Amp OTL by TDA2030 transistor is packed into this project.the power dissipation of 20W at 8 ohm or 30W at load 4 ohm
This is First Variable DC Power Supply 1.2V to 30V 1A using LM317. using a few parts and build easy with PCB layout and can fine adjust voltage output.
Not suitable for beginners!
Here is simple ICL7017 digital voltmeter circuit easy to build and cheap because it is high technology, by single IC,small number, along by LED 3 digit.