Rechargeable DIY Boombox: How to Make One

Rechargeable DIY Boombox: How to Make OneWhether you have got some spare parts you want to maximize or you are just fond of assembling things from scratch, we give you a handyman challenge worth a try. A 2.1 rechargeable DIY boombox project we have found on Instructables!

This boombox is powered by a Lithium polymer battery that can play for 18 hours when unplugged. It also boasts of USB charging capabilities, Bluetooth connectivity, an FM radio tuner, and a 3.5 mm jack. And as if these weren’t enough, this project can also be controlled remotely! But fool you not, for this project requires advance electronic knowledge and skills.

First, What Is a Boombox?

A boombox is a portable audio device that plays loud music. In yesteryears, it was primarily a radio tuner and a cassette or CD player with two large speakers. Notably, modern models are considered more of powerful speakers that can play from some sources. On top of radio stations they play, some boomboxes can stream music from mobile devices via NFC, Bluetooth connectivity or 3.5 mm stereo plugs.

How Do You Make a Rechargeable DIY Boombox?

If you’re interested in making boomboxes that are powered by rechargeable batteries, this version is worth a try:

Step 1: Gather all the materials and tools. You will need the following:

1 x Bluetooth/FM/USB/SD player module with remote control

  • 2 x Two-channel 3W PAM8403 audio amplifier
  • 1 x watertight container
  • 4 x 3W full-range speaker
  • 1 x 4-inch woofer speaker (4 or 8 ohms)
  • 1 x 12V USB charger circuit (disassembled from a 12V USB charger)
  • 1 x three-cell 2.2A Li-Po battery
  • 1 x Vernier caliper
  • 1 x drawing compass
  • 1 x permanent marker
  • 1 x 300-grit sandpaper
  • 1 x rotary tool
  • 1 x Leatherman multi-tool
  • 1 x electric drill
  • 1 x silicone sealant
  • 1 x super glue tube
  • 1 x 40W soldering iron
  • 1 x electrical tape
  • 1 x TDA2005 I.C.
  • 1 x 100kΩ pot
  • screw posts
  • heatsink 25V capacitors ( 2 x 220uF, 2 x 100uF, 2 x 2.2uF, 3 x 100nF, 1 x 10uF )
  • 1/4w resistors ( 1 x 120K, 1 x 2K, 1 x 1K, 2 x 12Ω, 2 x 1Ω )

Step 2: With the use of a Vernier caliper, take measurements of the outer diameter of your woofer and speakers. Determine as well the screw post distance of your Bluetooth/FM/USB/SD player module.

Then, transfer the woofer and speaker measurements on the front face of the watertight container. Using your drawing compass and marker, position the holes for the woofer in the middle and of each speaker in one corner. For the Bluetooth/FM/USB/SD player module, transfer the measurements on the right side of the case.

Step 3: After you have marked all the areas where the woofer, speakers, and Bluetooth/FM/USB/SD player module would fit, cut them out using your rotary tool.

On the top side, make a hole for the switch and beside it a hole for the DC jack.

Then smoothen the edges of the holes using the Leatherman multi-tool and the 300-grit sandpaper.

Step 4: From the inside of the container, try to fit the woofer in the middle hole and mark where the screw mount holes should be placed. Remove the woofer and drill holes in the marked areas. Fit the woofer back in and screw it in place. Then, seal the gap with silicone sealant.

Step 5: From the inside, position as well the four speakers in place using superglue.

Step 6: Make the necessary wire connections from the speakers to the two-channel 3W PAM8403 audio amplifiers and Bluetooth/FM/USB/SD player module. It would be helpful if you get a wiring instruction map for this.

Have these in mind as you do the wiring: (1) speakers have a common ground so do not ground the speakers; (2) the mains require thick wires; (3) maintain proper speaker polarity; and (4) the Bluetooth/FM/USB/SD player module has an internal regulator of 5-30v.

Step 7: Mount the PAM8403 amp module on the right and left speaker array.

Step 8: Get your 5v regulator from a two-ampere USB car charger. Disassemble the charger to get its circuit. Remove by desoldering its female plug. Then, solder the 5v-input parallel of the PAM8403 amp module to the 5v-output of the 12v USB charger.

Step 9: Next, make your mini amp PCB. Then, assemble your mono amp parts onto the PCB, soldering them to their respective pins.

Step 10: Having only one woofer, it then shares both right and left audio signals, with the L-channel connecting to the Bluetooth’s left audio out and the R-channel to the right audio out. The M connects to the woofer’s amp (audio-input).

Step 11: Lastly, connect the switch, DC charger jack, and Li-Po batteries to the setup. Then, give your project a run test. Close the watertight container when done.

Congratulations! You’ve got for yourself your very own boombox!

What Other Rechargeable Batteries Can You Use?

Lithium polymer or Li-Po batteries, like the one used in this project, have a low profile. They are lightweight as well. More importantly, they have a high energy density, which makes them a good choice if you’re counting on the long-lasting power performance of your boombox when outdoors or when away from power sources.

Unfortunately, Li-Po batteries don’t take being drained for a long time very well. So, you need to check on the power reserve from time to time. Otherwise, you’ll shorten the lifespan of these expensive batteries quicker than intended.

Aside from Li-Po batteries, you can also power your rechargeable DIY boombox with the following types of batteries:

·    Nickel-Metal Hydride or NiMH batteries

While they are safe, reliable, and easy to maintain, NiMH batteries can considerably add to the weight of your boombox. They are also bulky and have lower energy density than Li-Po batteries.

·    Lithium Ion (Li-ion) batteries

These batteries have higher power density and are cheaper than the lithium polymer ones. They are also lightweight, so they do not add considerable weight to your already heavy boombox. But Li-ion batteries are more risky to use, owing to its unstable nature. They require a protection circuit to assure safety.

Getting your boombox is fairly easy and shouldn’t cost you an arm and a leg, but nothing beats the satisfaction you can get from making your boombox from scratch. Give this project a try, tweaking it here and there, and share with us your experience and some tips.

 

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