What items still use a 9 volt battery

D sized batteries used to be made with Zinc so you could put some pool acid in a soda bottle, add the battery case and generate hydrogen gas. Just put a balloon over the top and you have a balloon that would rise.

2HCl + 2Zn --> H2 + 2ZnCl

Fun and a bit on the explosive side!
 
Smoke detectors and my mutimeter and had an active pickup bass guitar and an another electric guitar with a db boost function on it.
 
I noticed the same thing, few 9V on display in stores. Even the dollar stores used to sell a twin pack. To get a deal you have to buy an 8-10 pack to get under a dollar a battery if one is so lucky.
 
Back
Top