--- A 555 (even a CMOS 555) is kind of iffy at 5 minutes, so you might want to try this instead:
+---------+-----+------+ | Vcc | | | +V [510K] | +-->[250k] [0.1µF] | | [100K] | | HC4060 +-------+ | | +-------+------+------+ |K | O----->C +-------|Rs Rtc Ctc | [1N4148] [COIL]- - -| | | | | | O--> | +--|MR Q7 Q13 | +-------+ | | +------------+----+---+ | +---------->NO | | | C +---[1N4148>]---+ +--[510]--B 2N4401 | | E +---[1N4148>]--------+ | GNDSet the pot to 160K and the output pulse will be about 5 seconds long with a time between pulses of about 5 minutes and 20 seconds.
-- John Fields Professional Circuit Designer