Category Archives: iPod Touch & iPhone

Adding Aux Line-in (and USB Power) to an 03 Subaru Impreza Stock Radio

Finished Front Connections to Stereo
I was impressed with Jordan’s simple hack to add an auxilary input to a stock stero head unit and had to try it myself. As my head unit is rather busy on the front panel I routed the input jack into the back of the tray above. I also added a USB charging socket using a 7805 Voltage Regualtor and the data line configuration from Ladyada’s Minty Boost.

WARNING: Obviously opening up your radio and cutting/soldering risks breaking it and will most definitely void your warranty, be prepared to buy a new head unit if it all goes wrong.


Step One: Removing the Head Unit and Cage

On many Subaru’s you have to remove the centre console in order to remove the head unit cage. However on my 03 Impreza Sportswagon all you have to do is pop open the drink holder above the stereo and then gently pop the trim off from around the head unit. Unfortunately I did not figure this out until I had removed my entire centre console! So hopefully the same won’t happen to you.

Step Two: Locating the Radio Lines

Stero Head Unit showing Radio CardI’d recommend reading Jordan’s Post as a reference. You will need to dissasemble your stereo until you can find a point on the circuit board where you can safely cut the radio lines (FM or AM) and then reconnect them through the 3.5mm switching socket. Try and find points where components are soldered in to add your wires, soldering to a track is virtually impossible.

If you can’t locate the lines, you will need to do some diagnostics with a multimeter or give up.




Step Three: Wiring Up the Switching Socket/Jack

From wikipedia in a 3.5mm stereo jack the tip is left channel, the ring is the right channel and the  Base/last ring is the ground. You will need to look at the data sheet from your socket to determine which pins are which and then solder a wire to each. The pictures show the wiring I used for a socket I bought from Jaycar in Australia.









Step Four: Cut the Radio Left and Right Lines and Solder in the Socket

Since my stereo has the radio on a seperate little board inside, I severed the connection between the radio and main amp board for the two FM channels. In retrospect I would have been better finding a section of track to cut as the connection between teh two boards was really strong and I had to use a drill to cut away the connections.

Once the connections were severed I connected the OUT wire connections from the socket to the amplifier side of the lines and the IN wire connections to the Radio side. I soldered the ground wires to the same ground pin on the amplifier side of the stereo (green wire in step five picture).



Step Five: Test Connections with a Multimeter Then Glue

Soldered and GluedSet the multimeter to the beep test (resistance) and check that none of your lines are connected to each other and also that they are connected to the board (probe your connection and next connection along track). Once the connections are checked then you need to glue down the wires so they do not come loose during your next rally.






Step Six: USB Charging Circuit

For the charging circuit I soldered together a USB Socket and the components on the left as per the diagram. Covering the entire circuit in electrical tape to protect it and then soldering it to the VCC and Ground of the stereo. Once again I checked the connections and glued to hold in place.

The data lines attach into the resistor ladder network in order to be held at 2 volts each. This tells many products (Ipods etc – see the minty boost compatability list) to charge and draw half an amp.

Click the diagram for larger image.

NOTE: If you use a USB cable socket as I have you will need to thread the cable through the tray before soldering up the charging circuit.








Step Seven: Mount the connectors

Carefully re-assemble your stereo and route the cables out the back (you may need to bend the casing or drill a hole).

Drill a hole for the 3.5mm socket and mount it into the plastic tray using the screw on the socket and with glue at the back.

If your USB socket is a cable like mine, wrap some electrical tape around the cable as pictures to stop it pulling through and breaking the soldered connections.



Step Eight: Re-install

Plug in your stereo before re mounting and turn it on. Be ready to turn it off quickly if there is any smoke, sparks, or bad burning smells, if this happens then something is wired wrong, dis-assemble and re-check everything.

If it powers on without issue check the CD, AM/FM etc are all working as well as your new auxilary line in. Onces it is all working remount the stereo and re-attach the trim etc.

All Done!


How Apple should have implemented the controls on the new iPod Shuffle

Most people will have heard of the new iPod Shuffle by now and as you know it has the controls on the earphones and not the main unit. This means you can’t use it with good quality headphones or plug it into your stereo for playing music with friends etc. Which is just a pain, but then again anyone who sees this as a problem, probably isn’t in the target market for the shuffle!

Also isn’t this Sony’s design? They had an on wire control for their CD and MiniDisc players way way back.

Anyway I wanted to share how I thought Apple should have implemented the controls on the new shuffle.

The Mechanism

Rather than having the controls on the headphone wire, the shuffle body should have a capacitive strip down the front. The strip would sense your finger just like the click wheel on existing iPods.

Capacitive control on new ipod shuffle



You can then use a series of simple and intuitive gestures to control your music.

Gesture Control
shufle play Play/Pause

Touch once to pause or play the current song.

 shuffle next song Next Song

Slide your finger from left to right across the shuffle to go to the next song.

 shuffle previous song Previous Song

Slide your finger from right to left across the shuffle to go to the previous song.

 shuffle voice over Voice Over

Double touch the shuffle to have it voice over the current artist and song name.

 shuffle select playlist Choose Playlist

Slide your finger back and forth to activate the voice over playlist selection. Single touch to select a playlist after playlist selection has been activated.

 shuffle volume up or down  Volume

To increase the volume slide left to right and hold, let go when the volume is at the desired level.

To decrease the volume slide right to left and hold, let go when the volume is at the desired level.


I think that this setup would be much easier to use, headphone/stereo friendly and a lot simpler/cleaner looking.

It is also possible that the unit is too small and would start trying to play when you were clipping it on to things, but hey thats what the on/off switch is for right…

Worth upgrading ipod touch to 2.0 firmware?

Ipod Touch Remote app connecting to pc

Today I upgraded my ipod touch to the 2.0 firmware. Whilst the only main difference form the ‘January Upgrade’ that I also purchased is the addition of the ‘Apps’ section to the ipod, I still think the upgrade is worth the $12.99 (AUD). This is because of the free ‘Remote’ application that lets you control itunes remotely. It looks exactly like the normal player on your touch and is super responsive over wifi (Great for parties as music selection can be ‘passed around’ or as host you can maintain control).


  • Remote app is really good
  • Better email support (exchange)
  • I am sure some more useful apps will come along


  • $12.99 for a firmware update! most companies would supply this free apple.

Testing the memory limits of Safari on Ipod Touch

In order to find out the memory usage limit in safari on my Ipod Touch I wrote some javascript to grab chunks of data 500Kb at a time from a web service and waited to see how long it took to crash. The Touch ran smoothly right up to recieving 24Mb of data in memory (via javascript). At which point it promply crashed/stopped playing music and then shut down/crashed safari.

 This probably means that you should limit your pages to use around 4-5Mb of data maximum (in case the user has multiple pages open that are memory heavy). In reality I think you could get away with 10-15Mb as I doubt that any user will really open up more than 2-3 pages as this feature on the touch/iphone doesnt work that well.

 I also recorded the time it took to load 500Kb. For me this took around 23 seconds. In an ajax world this means you would not want to load more than 100Kb at a time as users would have to wait more than 5 seconds (5sec is a rule of thumb for max page load time). One second wait time would be better so a better target chunk size might be 20Kb depending on your connection speed of course.


The Verdict:

Use up to 15Mb of memory in your Iphone / Ipod Touch Safari Web Application.

Make web service calls of up to 100Kb. Aiming for a chunk size of 20Kb (or less for slow links).