I need some help developing a small circuit for a home project. I am looking to develop a circuit that operates on 12V, battery power, or even solar power if possible. I would like the device to fire a pulse to an electromagnet every 30-60 seconds using a timer or capacitor device. The electromagnet must be strong enough to pull a metal rod with a force about equal to what a doctor would use to check your reflexes in your knee.

As you can probably tell, I am on the beginner/amateur level so my terminology may not be the best. Essentially, I would like a small circuit device that can ring a bell every 30-60 seconds. Any help is greatly appreciated.