Podzuma
A few years ago I decided to build a portable iPod stereo for my stepdad. After finding a few designs online, I went with the Podzuma build by Darren Kuzma on Parts Express. It has a pretty simple electrical schematic which includes a battery, wall charger, amplifier, crossovers, and speakers. Though I lack speaker cabinet building experience, it wasn’t that difficult to make. You can view the original project here if you would like to see the materials used and the schematic. I made a few modifications to the schematic which I will address.
Overall, the circuit is pretty simple. The original schematic is on the left. It features a DC input jack, power LED, 12V Lead Acid battery, 12V DC Accessory (Car) Jack and an amplifier. I built the stereo when iPods were still relevant so I adjusted my version to include a 30-pin iPod port located on top of the speaker. I used an iPod car charging cable to provide power to the iPod. The cable also had an AUX out to be connected to the amplifier. The cable included a 12V to 5V USB charger (shown in the schematic). I ran the AUX out to a switch on the back to swap between the iPod or the AUX 1/8″ input jack.
As I stated, I built this a few years ago, but my stepdad began having issues with it. Mainly the DTA-2 amp that was in it started crackling and making weird noises. I believe this was related to the potentiometer that comes with it. Not sure exactly what was happening but it definitely was worse when I adjusted the knob or the ribbon cable that went to it. I knew that the amp needed to be replaced. While I was at it, I also wanted to refinish the cabinet. The original finish we applied was a dark stain/polyurethane combination that I wanted to redo with a lighter, more transparent stain.
He also experienced problems with the sealed lead acid battery. Initially, I followed the original schematic and used a 12V DC power adapter to charge the battery. I added a reverse polarity diode in series with the battery and a current limiting resistor. The diode created a pretty significant voltage drop (enough to bring the effective voltage down to 11.5V or so). Turns out, a sealed acid battery needs to be charged at a higher voltage then what is stated on the battery. In other words, a 12V lead acid battery should be charged by a charger putting out ~14V instead of only 12V. I found the best thing to do was to use a charger devoted to sealed acid batteries. I chose to use one with LED indicators to know when the battery finished charging. Here’s an example, Battery Tender
