this is a coin-operated countdown timer... basically, you drop coins into a coin slot, and preset minutes are added to the timer...
1. how to add a pause switch -- on/off switch to suspend/resume the countdown
2. how to add a push switch to add minutes to the time (bypassing the coin slot)
3. how to add a push switch to remove minutes from the time
4. how to speed up the countdown (2x or 5x)