Ridgeland
Member
- Dec 14, 2010
- 285
- 9
I made my own cable for USB to 5V power pin for my MID7015.
The attached photos shows the cable. The pinout for the USB can be found at
Pinout - Wikipedia, the free encyclopedia
I bought a 12V car adapter RCA AH55N for $10 at Menard's. It proved to be underpowered but I wanted the cable and pin. I had a 1 foot USB extension cord M-F so with cutting pliers, insulation cutters, sharp knife, soldering iron, shrinkable tubing and time I now have my cable.
The USB cable I cut open even had the correct colored wires with the correct assignment. I cut the cable leads at staggered lenghts so the solder joints would not be next to each other. I used shrinkable tubing around each solder joint. For the final cover I added a piece of stiff insulated wire as a splint (to prevent bending at the end of the solder) and then the blue shrinkable tubing.
After polarity the next major concern is the very small gauge leads in the USB cable (I guess 26 to 30 gauge). From
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies
I see that pushing 2A is a risk. So when I did connect it I stayed close by for the first half hour checking carefully for any hot smell of melting insulation and touching to see that the wires were not heating up. The wires stayed room temperature.
I have a 120V USB charger that delivers 2A. I connected the charger with a Kill-A-Watt meter to monitor the wattage. With the USB charger connected to 120V but not connected to the Coby the power consumption was 0 Watts (nice base). I drained the Coby to 33% battery charge and connected the USB cable. The draw was initially 7 Watts (7W/5V = 1.4 Amp). This dropped in minutes and stayed consistent at 5 watts almost through the duration of the charge. As the charge continues the battery percentage goes up, the battery voltage goes up and eventually the wattage drawn goes down. In three hours the charge was up to 98%. Checking at about 3 1/2 hours the green charge light was on and the current was 3 watts. Checking at 4 1/2 hours the green charge light was still on and the current had dropped to 0 watts. The Kill-A-Watt is an imperfect measurement as it measures energy going into the charger not out of the charger. For the EEs the power factor of the charger is 0.50 so the draw the electric utility charges is double the useful wattage (i.e. 5W = 10VA x 0.50 pf)
I then tested by draining the battery to 80% and connecting the charger. I played Angry Birds - a good energy drain of display, sound and CPU. From an app I learned the biggest three power drains are display, sound then CPU. The current draw was 7 watts, then fell to 5 watts. The battery charge increased while playing. So this should work for long trips with a bright display in a car in daylight.
The Wiki for the USB 2.0 specs says a USB device can draw as much as 0.5A. So this cable may be a good way to fry a motherboard. I will only use it with a charger not my computer. Shopping for chargers I kept seeing 2.1A for iPad. So I read the iPad manual. They let users charge the iPad from a USB socket! They only warn that the USB charge may be very slow and may not work, the 120V adapter being the preferred method. The presence of the iPad means there will be sources for 2A USB chargers, now or more soon probably.
That was my Coby distraction for the week-end. If you find such a USB charger cable for sell share the information in this thread for others.
Disclaimer: This may well be able to fry your Coby and fry your PC both, anyone doing this does so at their own risk to equipment, self and warranties.
The attached photos shows the cable. The pinout for the USB can be found at
Pinout - Wikipedia, the free encyclopedia
I bought a 12V car adapter RCA AH55N for $10 at Menard's. It proved to be underpowered but I wanted the cable and pin. I had a 1 foot USB extension cord M-F so with cutting pliers, insulation cutters, sharp knife, soldering iron, shrinkable tubing and time I now have my cable.
The USB cable I cut open even had the correct colored wires with the correct assignment. I cut the cable leads at staggered lenghts so the solder joints would not be next to each other. I used shrinkable tubing around each solder joint. For the final cover I added a piece of stiff insulated wire as a splint (to prevent bending at the end of the solder) and then the blue shrinkable tubing.
After polarity the next major concern is the very small gauge leads in the USB cable (I guess 26 to 30 gauge). From
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies
I see that pushing 2A is a risk. So when I did connect it I stayed close by for the first half hour checking carefully for any hot smell of melting insulation and touching to see that the wires were not heating up. The wires stayed room temperature.
I have a 120V USB charger that delivers 2A. I connected the charger with a Kill-A-Watt meter to monitor the wattage. With the USB charger connected to 120V but not connected to the Coby the power consumption was 0 Watts (nice base). I drained the Coby to 33% battery charge and connected the USB cable. The draw was initially 7 Watts (7W/5V = 1.4 Amp). This dropped in minutes and stayed consistent at 5 watts almost through the duration of the charge. As the charge continues the battery percentage goes up, the battery voltage goes up and eventually the wattage drawn goes down. In three hours the charge was up to 98%. Checking at about 3 1/2 hours the green charge light was on and the current was 3 watts. Checking at 4 1/2 hours the green charge light was still on and the current had dropped to 0 watts. The Kill-A-Watt is an imperfect measurement as it measures energy going into the charger not out of the charger. For the EEs the power factor of the charger is 0.50 so the draw the electric utility charges is double the useful wattage (i.e. 5W = 10VA x 0.50 pf)
I then tested by draining the battery to 80% and connecting the charger. I played Angry Birds - a good energy drain of display, sound and CPU. From an app I learned the biggest three power drains are display, sound then CPU. The current draw was 7 watts, then fell to 5 watts. The battery charge increased while playing. So this should work for long trips with a bright display in a car in daylight.
The Wiki for the USB 2.0 specs says a USB device can draw as much as 0.5A. So this cable may be a good way to fry a motherboard. I will only use it with a charger not my computer. Shopping for chargers I kept seeing 2.1A for iPad. So I read the iPad manual. They let users charge the iPad from a USB socket! They only warn that the USB charge may be very slow and may not work, the 120V adapter being the preferred method. The presence of the iPad means there will be sources for 2A USB chargers, now or more soon probably.
That was my Coby distraction for the week-end. If you find such a USB charger cable for sell share the information in this thread for others.
Disclaimer: This may well be able to fry your Coby and fry your PC both, anyone doing this does so at their own risk to equipment, self and warranties.
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