Short answer: yes, you can power both with a 12V 4A supply and NO, you can't use 24V 2A supply, it will fry everything most likely. Long answer: If one or both devices is sensitive to noise (eg an audio amplifier), powering two devices from the same supply could create noise that intereferes with normal operation (eg hum in speakers). It is not recommended to use 5 volts instead of the recommended 4. 5 volts, as the components in your device may not be designed to handle this amount of voltage. Depending on the device and the components inside, using a higher voltage than what is specified may damage or even destroy your device. Doing this may also void any existing 56,256. Sunny55. You cannot activate a 12Vdc relay with 5V. To have reliable operation they must have 66% the rated coil voltage (9V) to activate and will hold down to 10% Vcoil rated = 1.2V. A clamp diode is recommended just to protect a transistor driver from overvoltage. The chatter sound @ 13V proves nothing. The bad caps are both 6.3 V, 4700 µF and i was thinking of replacing them with 16 V, 4700 µF. Yes, you can pick a higher voltage without problems. but getting the better quality 105 °C rated one as the others ones are 85 °C rated. Again, yes, 105°C will last longer. HOWEVER: 3. These are motor capacitors, not electronic. 4.5 280v/ 5 250v/ 5 250v means the cap box has 3 separate capacitors inside, one that is the main Starting capacitor, likely the 4.5uF 280V one, and the other two are for speed changes. So low speed is both caps in series, middle speed is one of them, high speed is neither. Most engine management sensors are two-wire circuits that contain a 5-volt reference and a signal return wire or three-wire circuits that contain a 5-volt, signal return and auxiliary ground wire. Author Gary Goms provides two real-world examples of how two- and three-wire sensors can cause an intermittent rich operating condition. Depends on the voltage tolerance of the device. Likely it will work fine, if you're willing to risk it. When a device says a certain voltage, it doesn't need 4.5000000000V exactly. Typically if a device is designed to run on batteries, I.e. 4.5V = 3x1.5V batteries, it will for sure have a wider voltage tolerance as battery voltage sags at the Step 1: Transformer. it's an obvious to use a transformer. A transformer's main job is to transform power. In this case you need a step down transformer. A step down transformer transforms high power into low power. You might know that mains voltage in all countries aren't same. like Bangladesh's 220v and USA's 120v. 6lldIb.