The values of the various fixed resistors could be calculated either through this calculator software or using the following formula: The following figure shows another simple dual power supply circuit which can be customized to get any dual voltage between 3V and 15V. THe Electrically speaking, higher voltage can cause more amps to “flow”. This is one reason why getting the voltage correct on a power supply is so critical, because it can, in a sense, “push” too much electricity through a device and cause it to overheat or be damaged. Can too many amps damage a device? Nevertheless, the circuit that we design here will be useful because a) The circuit has the capacity to enable positive voltage and even negative voltage [at 3 volts, 5 volts, 6 volts, 9 volts, 12 volts, 15 volts respectively keeping the output of the current under 1.5 amps; b) Here’s the catch: just because the physical plug fits into your device does not mean that the polarity is correct. Example of a polarity indicator. (Image: Three-quarter-ten, CC BY-SA 3.0, via Wikimedia Commons)

If I knew what kind of resistor I can buy to solder in with a wire that would be about my only option. Sidestep all those unknowns and make sure to get exactly the right voltage from the start. Amperage

Considering that it should be achievable to adjust the output voltage to 3 variable ranges, the voltage regulator applied is a kind whose output could be fixed using a handful of resistors, as shown in the circuit diagram. The output voltage is determined using the formula If you look closely at the small print on many power supplies, you’ll see they’re rated for anything from 100 to 250 volts. This means most can work worldwide with nothing more than an adapter to account for the physical plug differences — no voltage transformer needed. Particularly when it comes to popular circular power connectors, make sure the expectations match. If the device expects the center connector to be positive and the outer ring to be negative, your power supply’s connector must match. There’s no getting around this.

Power supply efficiency is known as the amount of power actually provided to the internal circuitry, divided by the amount of power drawn from the mains supply. If a PSU is 50% efficient and is required to provide 50 Watts of power, 100 Watts will be drawn from the main supply. The extra 50 W is lost as heat. A 90% efficient PSU would draw 56 W in the same circumstances. What industries can power supplies be used in?The amperage rating of a charger or power supply is the maximum it can supply. A device being charged will only take as much amperage as it requires. If your device needs 0.5 amps to charge, and your charger is rated at 1.0 amps, only 0.5 amps will be used. The regulation of the negative voltage tends to be relatively more complex. The + input pinout of the lower opamp is coupled to the zero voltage '0', by means of a 6k8 resistor. Am I getting this concept wrong? Or is a special cable an impossible vision because the car adapter will only work if it is getting 12V and not 5V? An AC/DC adapter is made up of a central unit which draws power from an AC outlet, it then converts the power to DC that is used to charge the device. Each AC adapter has a specific power rating, measured in volts or watts that it can handle and the output of a device. Because of the power rating and the type of plug on the end, an AC adapter is not universal and can only be used with devices with the same requirements and connector. International Plug Power Supplies

For most applicationsI ADJ could be simply ignored since it's value will be too small. LM317 Symmetrical Power Supply with Current Boost Unfortunately the gauge of the USB 2.0 cable is really a high number (meaning that the wires are few and small). I’m thinking I should redo my cable and use a USB 3.0 cable because I think it may be able to handle the Voltage.It is my understanding that the volts you are trying to input should be the same or less than the device you are charging. While the amps should be the same or they can be slightly higher than the device you are charging. The above symmetrical LM317 dual power supply circuit can be further upgraded into a high current symmetrical supply, using the following configuration. The current boosting is delivered by the power transistors TIP3055 and TIP2955. Another LM317 Simple Dual Power Supply Circuit Of course I was excited to do it. My thought was that if the Nintendo car adapter charger steps 12 volts down to 4.6 Volts at 900 mA, then this new cable should step 5 volts down to 4.6 at 900 mA. But it did not work. In regard to positive volt it is preferable to use IC LM317 [-3V,-5V,-6V,-9V,-12V,-15V at 1A] and use LM337 as the negative volt. The voltage can further be controlled by S2 [+Vout] and S3 [-Vout]. The size of the transformer is set to 2A and furthermore the IC enables holding the heat sink. Uout = 1.25(1+R2/R1) + IadjR2, in which 1.25 signifies the reference voltage of the IC, and ladj indicates the current moving through the 'ADJ(ust)' pin of the device towards ground.