While on long family trips we bring along our Netbook or Laptop with use as a portable entertainment system. Most often a pair of headphones isn't enough. I also prefer to have a decent set of speakers. Unfortunately the Speakers built into most laptops are not decent and don't get load enough. So we have a $20 set of PC speakers we carry with use. Unfortunately they are a bit cumbersome and wires get tangled easily. So i figured it was time to do something about it.
In this Instructable i'll show you how i condensed the speakers down into a small package. I'll also show you how i integrated an Apple iPod dock into the unit allowing it to function as an iPod stereo and charger.
- Cheap set of PC speakers
- Spare iPod data cable
- Broken Western Digital 500Gb External Hard Drive
- 1/8" panel mount Headphone jack
- DC power jack (compatible with the one used by the speakers)
- Hot Glue Gun
- Wire cutters and strippers
- Soldering Iron
- Dremel tool with cut off wheels and scroll cutting bit
- Phillips head screwdriver
Step 1: IPod Charger
After opening the speaker set i went about verifying the voltage output of the speaker's wall adapter. It was odd since the adapter claims an output of 9V @ 400mA. My meter would show almost no voltage coming from the adapter. Yet it is able to power the system. So i went into my box of "warts" and pulled out one rated 9V @ 500mA. This adapter actually puts out about 15V without a load. The speakers seem to handle it fine with nothing overheating. Besides the power will be divided between the speakers and charging when an iPod is docked.
Next i went about building a charge circuit for the iPod dock. I used a very basic circuit using an LM7805. I quickly found that you need more then just 5V going to the power leads of a USB cable to get an iPod to charge. So i found a great instructable on How to get your iPod to charge with your homemade charger. So i broke out my breadboards so i could prototype the circuit to ensure i get it right. There seems to be allot of hit and miss with different resistor combos people have used. Since I didn't have the mentioned resistor values on had i broke out the trust Voltage Divider calc on my iTouch and went about finding a good combo using what i had. From the instructable i knew i needed 2V going into the D+ (green wire) and about 2.7V going into the D- (white wire). I ended up with the following based on the 5.03V output my charge circuit offers:
- R1= 22K Ohms
- R2= 26K Ohms (1x 22K resistor and 1x 4K resistor in series)
- R3= 15K Ohms
I hooked everything up then went about testing the circuit before connecting it to my iTouch. Making sure sure that the D+ (green wire) was at 2V and the D-(white wire) was at 2.7V. I found that the diagram on the above mentioned instructable has the voltage divider upside down. R1 needed to be coming from the DC input and R2 and R3 need to be attached to ground. Otherwise the voltage readings across the data pins wasn't reading right. So i connected everything as my schematic shows and all the measurments worked out. Since everything looked good i plugged in my iTouch and it worked without a problem. Even with the voltage across D- at only 2.27V. I am using a mini-USB B cable like those found on many cell phones. The iPod connector i'm using is from a charging kit and is an adapter that plugs into a mini-USB B cable.
Before moving everything to a board i wanted to hook it up to the speakers and see how the wall adapter handled the load from the speaker and the charger. Everything stayed powered with room to spare. The output voltage of the charger was 5.03V without a load. Once the iTouch was connected it only dropped to 4.93V. Overall not bad for such a basic circuit. Since everything checked out i was ready to solder the charger to a board. But not everything can go onto the board yet. The power input and USB wires need to be left off till final assembly.
After laying out the components on the board i soldered everything down and ran wires over the top to where i wanted the USB cable to connect. Since the wires from the USB cable are so thin i used a healthy helping of hot glue to secure then to the board so they won't move and break. I did a quick test to ensure everything still worked as it should the the charger is complete.
Step 2: IPod Dock
I have an iPod dock adapter plate that came with my 2nd Gen iPod Touch. So i altered that to be the dock on top of the can. First i used a file to widen the slot in the bottom to better accommodate my iPod connector. The i used a scrolling bit in my Dremel to cut a space to allow a head phone jack to be mounted.
Next i went about mounting the iPod connector and the headphone jack. The jack i'm using is from the speaker set. (As mentioned before the final product will use a panel mounted jack and a double male cable to connect the speakers to a PC or laptop.) First i set the iPod connector in its slot and set it about 1/16" up from the bottom of the bock plate. I wanted the connector as close to the bottom as possible but still allowing the plate to keep a pinch on it. I then hot glued the corners of the connector to the dock plate. Next i plug an iTouch into the dock and connector. This allowed me to plug in the headphone jack and have it perfectly aligned. I was then able to fill all the gaps with hot glue and make everything nice and secure.
Step 3: Preparing the Case
For the case i wanted something that was nice and compact. I considered many options and design ideas before i settled on this broken Western Digital 500Gb External Hard Drive. With a little coxing the 2 pieces of the body snapped and slid apart. The Hard Drive and electronics popped right out of the case. Now it was time to see if everything would actually fit in that case.
The speakers will sit in the back of the unit facing down. Each speaker will be angle to the side of the case. Both the speaker amp and charging circuit will be up front. The iPod dock will go right over top of the speakers and there will be just enough clearance for the headphone jack top fit. It was then time to start making holes in the case.
To ensure i get the holes right for the front plate i used the front face of the original speaker housing to make a templet. I then used a 1/16" drill bit to start the center of each hole. I know the pictures shows a hole for the Headphone jack on the front but after drilling all the starter holes i realized the headphone jack stuck out too far. Which would make it impossible to get the amp all the way through. So the head phone jack was removed. For the LED hole i finished it off with a 1/8" bit. The other 3 holes will drilled to 1/4". Since i didn't have a drill bit bigger then 1/4" and smaller then 3/8" i used my files to open the holes the rest of the way. With the holes finished i did a test fit to make sure everything lined up as it should. I then found the LED stuck out too far and did my best to move it as far back as possible. It left me just enough room so that the nobs could be put back on the pots but forces me to use Hot glue to mount the board in the case rather then a nut on the pots.
Next i placed the speakers on bottom of the case to drill the 1/16" starter holes for the screws that would hold them in place. I finished off the holes with an 11/64" bit. I went ahead and mounted the screws onto the case that will hold the speakers. Each screw needs 3 nuts. 1 to hold the screw to the case and 2 to pinch the speaker in place. I temporarily mounted the speakers in place to help me gauge the placement of the iPod dock. I had to place the dock slightly off center to make room for the connectors.
The hole for the dock only needs to be big enough to fit the parts the fit below the main part of the dock. Once again i created a paper templet for the hole i wanted to cut. I then broke out my 3/8" Drill bit and drilled a series of holes across the templet area. Then it was time to use my Dremel with scrolling bit to clean out the rest of the plastic. Once i was sure that the dock would fit in the oval hole i marked off the notch protrusion on the dock and cut the opening so the dock will sit flush on the case. Another test fit and everything is good to go.
Last was the back plate only a couple of mods needed here. First was using my Dremal and scroll bit to cut off the brace in the front. Then a bit of filling on one of the holes for the Fire Wire port to make room for the DC jack. The hole for the DC on the Drive will house the Headphone Jack for input from a PC/Laptop.
Step 4: Final Assembly
Now came time for the hardest part of the build... cramming everything inside this little case.
First i needed to do final preps on the Electronics. So i shortened the wires to the Speakers and soldered them into place. I also shortened the wire for Audio input and soldered the Headphone jack on. The wires that go to the DC jack where stripped and tinned in preparation for soldering to the Jack. Next i soldered the Power wire from the Charging circuit to the speaker amp. The i stripped and tinned the Audio wires from the dock in preparation for them being soldered to the speaker amp. Now everything is ready to go in the case.
Now comes the hard part. The Right side Speaker went in first to prevent clearance issues when its time for the dock to go in. I flattened the Corners of the speaker so it can be held tight at an angle on the screws. I used a bit of hot glue to help lock the nuts into place and along the opposite side of the speaker to prevent vibrations. Next i put the dock through its mounting hole but left it unsecured. Then soldered the dock's audio cable to the speaker amp.
With that done it was time to get the electronics inside the case to the general area it needed to be in. I could then mount the Left Speaker, bending the corners and securing it with hot glue. Before i could mount the speaker amp i had to remove the LED indicator light and the small section of board it was attached to so the amp could fit into the face correctly. So i had to remove the Left speaker, pull the amp board out. make the cuts needed with my wire cutters and put it all back together again. Now i could mount the Speaker amp in place. The pots on the amp didn't have any washers or nuts so i had to pull one from a pot i had on hand. With the amp good and secure it was time to glue the charging circuit to the bottom of the case.
Now i could go about plugging in the USB cable to the dock. and securing it with hot glue. Then the dock gets mounted and glued into it slot. I had to use a couple of clips to hold the dock in place while i glues it. I noticed that my wire for the power plug came up a bit short so i had to solder on an extension to it. Next i attached the DC jack to the back side of the case and soldered the power wire in place. Before closing it up a hooked everything up and made sure it works. Its a good thing i did cause i wasn't getting any sound/ I i pulled the Left speaker and amp out. I noticed that when i removed the Headphone Jack from the board i left the L and R channels open. So i soldered in a couple of jumper wires and we where good to go. I also noticed the 7805 was getting pretty hot. So i found a heat sink and put a dab of thermal compound on it and bolted it to the 7805.
Now that everything checked out i attached the Audio input jack onto the back plate. I also covered the power and audio jacks with electrical tape in case anything made contact with the speakers.
Step 5: Completed
So here it is. A nice compact PC speaker set with iPod Touch dock! The speakers sound no better or worst then they did in there original housing. The system works great with my 2nd and 4th gen iTouchs. Overall i'm very pleased with the end result. There where troubles along the way as there are with most projects.
Done in time to give it to my wife for Valentines day. She's been wanting a set of speakers for her iTouch.