iPod Car Charger w/ Audio Out

[luna5]

I have been working on a circuit design that would allow me to charge my iPhone/iPod classic 120 GB from my car. I am going to use power from the back of the cigar lighter sockets and put it into this circuit.

The plan is that it will step the voltage down the a usable charging voltage for the iPod. I have also had to use a voltage divider to provide power to the D+ and D- pins on the USB plug, apparently the phone will not charge with out it.

There is also an audio out section there that will basically use the GND, L Audio and R Audio and this will be wired into a 3.5 mm plug to go to my car sound system. There is also a 1 M Ohm resistor going from pin 21 on the iPod to GND to tell the iPod to shutdown when power is lost.

I am unable to breadboard this ATM as I don't have the voltage regulator or any rated capacitors. I have drawn up the breadboard design with Fritzing (see below). Now to the question, can anyone see any issues with my design? I am a little worried about how hot the LM7805 will get and also concerned about if the common ground is going to mess with my audio? For reference here is the iPod Pin out.

Breadboard layout Breadboard layout

Schematic Schematic

Parts list

12-14v power Car Battery
C1 4.7uF 50V Electrolytic Capacitor
C2 0.1uF 50V Electrolytic Capacitor
J1 Generic female header - 10 pins (Ipod)
J2 Generic female header - 3 pins (Audio)
LM7805 LM7805
R1 1MΩ Resistor
R2 47kΩ Resistor
R3 47Ω Resistor
R4 150kΩ Resistor
R5 100kΩ Resistor
PCB layout PCB layout

 

[Olddawgsrule]

I assume you found an electronic's forum to post this on.. If not let me know. I know a site with some pretty smart folks in it that may be able to assist.

Uncertain of the rules of posting another site, so PM me and I'll pass it.

 

[pm-r]

Urrr…hmmmm…???

Do I dare ask why you don't just buy one that's already been made, and often complete with cables, and often just for a few dollars at your locals "Dollar Den" type store???

They sure work well with our iPhone/iPods.






- Patrick
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[Olddawgsrule]

The fun part Patrick, is in the build! Reality, most store bought don't do what you really want.

Example is I have a voltage regulator on a solar pump I use in my Soaker Tub. Yes, I could buy it on Amazon for $20. Cheap enough.. What I would buy doesn't give me what I really want, close, but...
For $1.95 I bought the module and wired it myself. I have what I want.

Now, I did buy the solar charge controller cause the build was more than what I wanted to do. $10 was cheap enough to sway me!

Sometimes, it's all in the build!