Get a clue.
The Air India clock was made for automotive use. That's why it could run on a 12-volt lantern battery.
If the boy was used as a means of conducting a dry run to test security measures at a typical Texas school, then no explosives or batteries were required to complete the task of introducing a dummy IED to see what would happen. The next IED brought into a school may not be a dummy.
You'd make a lousy terrorist.
If you're going to insist on fitting your time bomb into a pencil case, a Casio F-91W would be a far better choice of timer:
 AQ watch timer on perf board (2002) |
No need for a hulking Micronta and its enormous lantern battery! If you're careful, you might even be able to get some pencils into your pencil case to show teach. Remember, bombs are not supposed to look like bombs!
The watch runs on its own internal battery. The alarm is wired to a relay. When it goes off, the relay sends the 9-volt battery's current through the external leads, setting off whatever they are wired to.
Check out this little catalog for more ideas!