For best results, always use a new 9V battery to power the memory saver. First, determine the positive and negative terminals. Then remove the negative terminal clamp from the battery post first.

Holding the 9V battery, lightly brush the terminals against any part of the steel wool, then take the battery and your hand away. To get the reaction really going, try blowing gently on the lit wool.

It’s just a simple modification of the plate the coil is wrapped around. The second is adding 9V battery terminals to a cell phone. Neither project is practical, but they’re still fun.

9V batteries are often found in devices that aren’t used very often. If you use a NiCd rechargeable battery you may find it completely discharged by the time you need it. Capacitors on the other ...