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iPod Charger Adaptor Charge any iPod using a standard 5V plugpack & this simple circuit By JOHN CLARKE This simple iPod charger adaptor uses just a few parts and mates with a standard 5V switchmode plugpack or a standard USB supply/charger. If you already have a 5V plugpack, it will cost you less than a proprietary charger and is easy to build. W HILE iPODs can be charged via a computer USB port, this is not always convenient and a separate charger is more useful. That way you can charge from the 230VAC mains or from a USB power outlet that plugs into the lighter socket of a car. However, iPod chargers from Apple and other suppliers can be expensive, while lowcost chargers bought online might not work with some iPod models. Generic USB plugpack supplies and chargers are much cheaper but they won’t work with iPods. Instead, you will be left with a “charging is not supported with this accessory” warning. However, with just a few minor additions, you can get a generic 5V supply/charger to work. Back in February 2006, we published an iPod Charger that comprised a 5V switchmode regulator fed from a 9-15V DC plugpack and the output was via a USB socket. It was designed to charge the first generation (1G) iPod nano available at the time. Later, we siliconchip.com.au published modifications to enable the charger to work with subsequent iPod releases from Apple. Essentially, four resistors have to be added across the 5V supply to provide a DC voltage at the D+ and D(data lines) of the USB socket. These are required for iPods to recognise the charger as valid before charging occurs. Now in 2013, an iPod charger can be much simplified. We can just use a cheap 5V regulated plugpack or USB supply or charger directly. Add a USB socket and some resistors to set the voltage at the D+ and D- inputs on the USB socket and that’s all that is required. Circuit details Fig.1 shows the circuit. The 5V supply connects to the 5V and 0V terminals, ie, pins 1 and 4 respectively of the type “A” USB socket. Resistors R1 and R2 form a voltage divider network across the 5V supply for the D- (Data minus) input while R3 and R4 set the voltage for the D+ input. A 1kΩ resistor provides current limiting for the power LED (LED1). We used a blue LED but any colour could be used including red, green, yellow, orange, white and aqua. Construction The parts are assembled onto a PCB coded 14108131 and measuring 18 x 60mm. Fig.2 shows the layout details. Install the resistors first, checking the values as you go with a digital multimeter. Table 1 shows the values for resistors R1-R4 to suit different iPod modelss (and for the Samsung Galaxy Tab2), while Table 2 also shows the resistor colour codes. It’s just a matter of selecting the resistors to suit your particular device. We recommend that these resistors are only tack-soldered in first and the charger adaptor tested before fully soldering the resistors directly onto the PCB. Make sure that the supply August 2013  57 Par t s Lis t +5V R3 R1 1k 5V SUPPLY INPUT 1 2 A TO iPOD 3 D+ 4 l LED1 R4 K USB TYPE A SOCKET R2 LED 0V SC Ó2013 1 PCB, code 14108131, 18 x 60mm 1 5V 1A regulated plugpack (eg, Jaycar MP3144, Altronics M8903) OR 1 5V USB charger/supply and 1 USB “A” line plug (Jaycar PP0790) with a length of lightduty figure-8 wire OR 1 USB type “A” plug & cable cut from a USB extension lead 1 PCB-mount USB type “A” socket (Jaycar PS0916, Altronics P1300) 1 75mm-length of clear 20mm diameter heatshrink tubing 1 3mm LED (any colour) (LED1) CON1 D– i POD CHARGER ADAPTOR K A C 2013 +5V R1 R2 R4 LED1 R3 A 1k 0V 14108131 13180141 Fig.1: the circuit uses just a few resistors, a power indicator LED and a type “A” USB socket. Power comes from a regulated 5V plugpack supply. 4 3 2 1 Fig.2: install the parts on the PCB as shown in this diagram. Resistors R1-R4 are selected from Table 1 to suit the iPod model. LOOP WIRES THROUGH HOLES This view shows the completed PCB. Make that sure the LED is orientated correctly. you will be using can deliver the necessary current if you want to charge at 500mA or 1A. The LED indicator is mounted directly on the PCB. Make sure it is orientated correctly with the anode (longer lead) inserted as shown on Fig.2. Solder its leads quickly to avoid heat damage. The USB socket goes in last. It must be pushed right down onto the PCB before soldering its outer mounting lugs soldered. Its four pin connections can then be soldered. The 5V power input can come from either a 5VDC plugpack or a USB supply (eg, a plugpack with a USB socket). As shown, the leads from a plugpack are directly soldered to the 5V and 0V terminals after the wires have been looped through two holes at one end of the PCB. This is done to provide stress relief for the connections. Make sure the that the plugpack’s leads are connected to the correct pads. If in doubt, check the voltage between its leads before making the connections. If you intend using a USB supply, a cable fitted with a USB type “A” plug at one end will have to be wired to the PCB. Fig.3 shows the details. Note that we do not mean using a USB supply on a computer here, since Resistors (0.25W, 1%) 1 33kΩ 2 15kΩ 2 22kΩ 1 10kΩ 1 18kΩ 1 1kΩ all iPods can be charged from a computer USB port. However, USB ports on a charger are different in that they supply power via pins 1 and 4 of the USB socket but there is no communication via the D+ and D- lines. Making the USB cable You can obtain a suitable cable by cutting off the socket from a USB extension cable (ie, the socket at the opposite end of the cable to the type “A” plug). That done, strip back the insulation and connect the red wire to the +5V input on the PCB and the black wire to the 0V input. The unused white and green data wires must be cut short and insulated so they can not short to each other or to any other parts. Table 2 shows the wire colours in a USB cable. Alternatively, you can use a USB Table 1: Selecting Resistors R1-R4 iPod touch/iPHONE/ iPod NANO 2G iPod touch/iPHONE (if product allows for 1A charge) D- <at> 2V D+ <at> 2V 500mA charge D- <at> 2.7V, D+ <at> 2V 1A charge R1 = 22kΩ R2 = 15kΩ R3 = 22kΩ R4 = 15kΩ R1 = 18kΩ R2 = 22kΩ R3 = 22kΩ R4 = 15kΩ 58  Silicon Chip iPod Mini, nano 2G, Shuffle 2G D- <at> >3V, D+ <at> >3V 250mA charge (Mini and nano), 100mA ( Shuffle) R1 = 22kΩ R2 = Omit R3 = 22kΩ R4 = Omit iPod Mini iPod nano 1G and iPod Video 5G D- <at> 0V, D+ <at> >3V 100mA charge D- <at> >3V, D+ <at> 0V 500mA charge R1 = Omit R2 = 22kΩ R3 = 22kΩ R4 = Omit R1 = 22kΩ R2 = Omit R3 = Omit R4 = 22kΩ Samsung Galaxy Tablet D- <at> 1.2V D+ <at> 1.2V charge unknown or ≤1A R1 = 33kΩ R2 = 10kΩ R3 = 33kΩ R4 = 10kΩ siliconchip.com.au 0V +5V 5V DC PLUGPACK Fig.3: power can come from a 5V DC plugpack or from a USB supply (eg, a plugpack with a USB outlet). The diagram below shows how to connect a USB cable to the adaptor PCB. 0V D+ 4 3 2 D– 1 +5V TYPE “A” USB PLUG (TO USB SUPPLY) CONNECT THESE TWO WIRES ONLY TO ADAPTOR PCB Fig.4: the pin connections from a type “A” USB socket. Use a DMM to check the 5V output from the adaptor PCB before connecting it to an iPod. USB TYPE A SOCKET VIEWED FROM FRONT PIN 1 (5V) PIN 4 (0V) PIN 2 (D–) ALTERNATIVE SUPPLY WIRING PIN 3 (D+) Table 3: Resistor Colour Codes   o o o o o o o No.   1   2   1   2   1   1 Value 33kΩ 22kΩ 18kΩ 15kΩ 10kΩ 1kΩ type “A” line plug (eg, Jaycar PP0790) and connect this to the PCB via a length of light-duty figure-8 cable. Checking output polarity It’s imperative that the output polarity from the adaptor is correct. This means that after connecting the iPod Charger Adaptor to a 5V supply, you should check the polarity at its USB output socket before connecting it to an iPod. In addition, if the incoming supply polarity is correct, then the indicator LED will be lit (provided it has been installed the right way around). Fig.3 shows the pin connections as viewed from the front of the USB socket. Using a multimeter, check that pin 1 is at +5V and that pin 4 is 0V (both siliconchip.com.au 4-Band Code (1%) orange orange orange brown red red orange brown brown grey orange brown brown green orange brown brown black orange brown brown black red brown 5-Band Code (1%) orange orange black red brown red red black red brown brown grey black red brown brown green black red brown brown black black red brown brown black black brown brown Table 2: USB Cable Colours Pin Wire Colour Name Function 1 Red VCC +5V 2 White D- Data - 3 Green D+ Data + 4 Black GND Ground with respect to the 0V pad on the PCB). When you are certain that the supply polarity (and voltage) is correct, the adaptor can be used with your iPod. You should be greeted by a charging indication when the iPod is plugged in. If charging does not take place or you get the “charging is not supported with this accessory” warning, check the iPod model that you have and check that the correct resistor values have been used for R1-R4. Once everything is working, the resistors can be resoldered and the PCB covered in heatshrink tubing. If you do not have clear tubing, then used coloured heatshrink and cut a small slot in it for the LED to protrude through before shrinking the tubing SC down with a hot-air gun. August 2013  59