Hi everyone, I'm not sure if Class D is the right subforum for this, so let me know if there's a better section on the site for this.
A while ago, I got this old portable tapedeck from work, the kind they used for learning languages at school and for the Cooper test at gymnastics in the 80's en 90's. This one was a DAN-SOUND AV-15. It was powered by 230V or 6x 1,5V batteries.
I also had this lithium battery lying around, which I intended to use in an electric scooter, but was the wrong voltage.
So I thought: why not combine both to make a great oldschool boombox? I did and it worked!
By using a step-down converter I created the necessary 12V to power the tapedeck and the amplifier itself. And by installing a car USB charger I can now connect a bluetooth transmitter and charge my phone. The USB adapter includes a voltmeter to see remaining battery power.
The disadvantage of this deck is that it has only one woofer, so only mono sound. The sound quality is poor overall, lot of hiss. And no high frequencies. I'm planning to attach cheap old portable stereo mini speakers which run on 4,5V battery power. Just to add some stereo sound & more high frequencies.
It has been a fun project so far. I'm certainly not planning to create a perfect sounding machine out of this.
Warning: working with 24V DC lithium batteries can cause a lethal electrical shock. Take appropriate safety measures.
A while ago, I got this old portable tapedeck from work, the kind they used for learning languages at school and for the Cooper test at gymnastics in the 80's en 90's. This one was a DAN-SOUND AV-15. It was powered by 230V or 6x 1,5V batteries.
I also had this lithium battery lying around, which I intended to use in an electric scooter, but was the wrong voltage.
So I thought: why not combine both to make a great oldschool boombox? I did and it worked!
By using a step-down converter I created the necessary 12V to power the tapedeck and the amplifier itself. And by installing a car USB charger I can now connect a bluetooth transmitter and charge my phone. The USB adapter includes a voltmeter to see remaining battery power.
The disadvantage of this deck is that it has only one woofer, so only mono sound. The sound quality is poor overall, lot of hiss. And no high frequencies. I'm planning to attach cheap old portable stereo mini speakers which run on 4,5V battery power. Just to add some stereo sound & more high frequencies.
It has been a fun project so far. I'm certainly not planning to create a perfect sounding machine out of this.
Warning: working with 24V DC lithium batteries can cause a lethal electrical shock. Take appropriate safety measures.
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ClassD amplifiers usually don't hiss as others. The lack of high frequency notes may be because the amp is designed specifically to manage lower frequencies. Depending on the switching freq of the amp, it may or not go to higher frequency response.
Keep an eye on the skate battery. Recently an entire house catched fire because of one of them, with several deaths.
Keep an eye on the skate battery. Recently an entire house catched fire because of one of them, with several deaths.
Thanks for the tip about the frequency. I guess I'll just have to find out if these tweeters respond.
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About the dangers of lithium batteries: Yeah I saw it in the news, terrible!
Try using modern low noise transistors in the first stage.
