The vast majority of hobby electronics projects run on batteries. Simple enough, but some projects need more current or higher voltages than batteries can easily provide. Instead of building a power supply that converts household
AC current to a DC voltage for your project, you can make things much safer for yourself by using a wall transformer to convert AC to DC.
All the working parts are self-contained in the wall transformer. As long as you don’t try to take it apart, you don’t expose the AC house current. Sometimes, you need to work on a project that uses your 117 volt AC house current directly. In those cases, you can’t resort to relatively safer batteries.
No hiding behind a wall transformer either. For these projects, always exercise caution. Although you’re being super careful, you can further minimize the hazards of working with circuits powered by AC house current by following these basic guidelines:
Always keep AC circuits covered
A little sheet of plastic works wonders.
Never circumvent any fuse protection used on the device
Don’t use a fuse with a too-high rating and don’t bypass the fuse altogether.
When troubleshooting AC circuitry, keep one hand in your pocket at all times
This prevents you from accidentally touching things with your hand that you shouldn’t. Use the other hand to manipulate the testing apparatus. Avoid the situation where one hand touches ground and the other a live circuit. The AC can flow from one hand to the other, straight through your heart.
If possible, use the buddy system when working with AC circuits
Always have someone nearby who can help you in case you get a nasty shock.
Double- and triple-check your work before applying power
If possible, have someone who knows a little about circuits inspect your handiwork before you switch the circuit on for the first time.
Periodically inspect AC circuits
Periodically inspect AC circuits for worn, broken, or loose wires and components and make any necessary repairs. When testing AC operated circuits, first remove the power. Unplug the power cord; don’t just switch off the power at an outlet strip. You can easily tell when you’ve pulled the plug from the socket, but it’s harder to tell if those little electrons are still swirling around the outlet strip.