This allows:
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
I’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
Set 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!
My friend is part of SOAK (Smart Operational Agriculture Kit) and needed some help putting together a demonstration sprinkler for the project. We ended up with a ‘sprinkler without water’ which can be activated from .NET (we did consider spraying onlookers with water :) ). The main electronics is a serial port controlled switch built using a TIP41C transistor which is activated from a ‘Switch’ class in C# .NET. The SOAK team then wrapped the class in a web service for use with their project.
Switch Features:
1x USB to Serial Port Adapter [$25] (These can be had for $10 if you are running XP, but ones that work with vista are $25 to $50 dollars and I am yet to see one that works with 64bit Vista which is a shame)
1x TIP41C transistor [$1.30]
1x DB9 Plug [$1.00]
1x DB9 Casing [$1.00]
1x Wires [$2] (I’ll let you decide how long you want them, but you will need at least a metre or so.)
1x Battery/Power Source
1x Servo Motor [$10]
1x Roll of electrical tape
1x Sprinkler [$5.00] (I got mine from the local ‘discount’ store)
2x Hours of time [$100?]
1x Soldering Iron
1x Wire Cutters
1x Serial Port Switch C# .NET Sample project
Before you start soldering you might want to check that the circuit is working using a breadboard or just twisting the wires together.
Attach Leads to components
Link the components together
Refer to this diagram
Once all the components are soldered together insulate any bare wires with electrical tape and pack the transistor and short wires into the DB9 casing leaving the two long wires protruding through the hole at the back of the casing.Then screw/clip it together depending on your casing.
You will need a copy of Visual Studio 2008 (Web Developer is fine) to run the sample project. All you should need to do is plug the serial switch in and run the project and it should find the serial switch port automatically. If not there is probably something wrong with your loopback connection (pins 2 & 3) so you might want to check that. If you are having problems the SerialPortSwitch.cs file is well commented, have a look in there. To operate the project press once to turn it on and once to turn it off.
Building the sprinkler part was a matter of gluing a servo motor to the sprinkler and then attaching some wire arms to the servo horn to actuate the ‘twacker’ on the sprinkler. The wires were run out the sprinkler water inlet and through the ‘hose’ so that they could not be seen. The pics below should give you an idea of how it was all put together.
This switch is not isolated. Meaning that whatever you drive with the switch could feedback into your serial port (eg. damage your computer). Replacing the transistor with an optically isolated component would fix this.
Chris has a nice circuit on his blog that is opt-isolated and can handle low load mains: http://hmmtheresanidea.
{gallery}netswitchsprinkler{/gallery}
Seeing this article on Hack A Day (and another one where it is connected to an apartment entry buzzer button) got me thinking about a way to make mobile phone activated switch that is simple with as few parts as possible (and cheap). The idea I had was to utilize the existing smarts of a mobile phone coupled with its vibration motor to power a relay or press a button.
WARNING: This is hack will alter your phone and any servo’s permanently and may break them permanently. Perform these modifications entirely at your own risk.
To get started you will need the following bits.
The two black and silver things above are pager motors. If you need more reference do a google image search on ‘pager motor’.
Now put everything back together how you pulled it apart. Except make sure the two wires you have attached poke neatly through your phones newly made hole.
Now that the modifications to the phone are done it is time to modify a servo.
This will depend on the phone, but what you need to do is set your phone to vibrate mode so that calls activate our newly installed servo.
If you used a newer phone you may be able to set it up to only vibrate for certain callers.
Now you just need to use some double sided tape to attach the servo to a switch or button so that when the servo turns it will press the button.
Call your cell phone! The servo motor should turn and activate your device. You may need to re-position your servo for it to work well.
Here is a video of my test:
Mobile Phone Switch Video.mp4
I performed the following tests during development of this hack.
Initially I connected the phone wires to a bread board with two LED’s in opposite polarity to see the signal produced from the pager motor connections. By using two LED’s like this I was also able to ascertain the polarity of the wires.
I also used my multimeter to measure the voltage produced by the pager motor connections. The voltage was 3.3 volts.
Also not pictured I put a 3300uF capacitor into the circuit. This was relatively effective at smoothing the pulses produced by the phone. This meant you got a stable 2v for around 3 seconds which would be good for powering a relay or transistor.
Thanks for watching.
My friend and I bought some PIC16F690 microprocessors. However we didn’t realise that our DIY Kit 150 programmers did not support the 16F690. Luckily a new firmware and software update is available (Beta) which supports the 16F690. Read on to see the process I used to upgrade my programmer and program my 16F690.
You will need the following:
The DIY Kit 150 programmer has a firmware chip (a pic16f628a) which can only be used with the corresponding verison of Micro Pro. In order to upgrade to the new version we must program and install a new firmware chip to use with the new version of Micro Pro.
Upgrading your programmer:
Programming your 16f690 via ICSP:
A couple of days ago engadget featured this airline USB travel charger that charges your device really slowly from the aircraft audio jack. I wanted something cheaper better so i could use my ipod, phone and camera during my international flight. So I made this AA battery powered USB charger form parts I had lying around.
What you will need:
So construction is pretty simple:
NOTE: Check your polarity (+ve’s and -ve’s) and voltages with the multimeter after each step.
UPDATE NOTE (21/10/2007): Originally I used a voltage regulator however the 5-6v from the battery pack was not enough for it to sustaion 5v so I had to remove it to get it to charge properly. The max output voltage with 4 AA batteries is 6V so it is unlikely to hurt any usb things.
Happy Charging!
NOTE: This setup will not charge all things (it works with my ipod, but not my motorola phone). This is because in the usb spec devices are supposed to contact the host (pc or usb hub) and request high power mode. As this setup has nothing to request high power mode from, the device will never try to charge (as it will assume high power mode is unavailable).
The Minty Boost Kit has the electronics required for most usb devices to work.