"Perpetual Motion" Machine

I tried to build a device that most people have probably seen before: a bouncing ball that seemingly defies gravity.
Of course, physics still applies, and it's well-known how this device is made. I tried to make it with the materials I had on hand.
The falling ball needs to be accelerated so it has enough energy to jump back to its starting position and fall again.
It turned out to be harder than it initially seemed.
A fairly powerful electromagnet is required for this. The electromagnet I had was 6V, and its strength was quite low.
The only way to increase its strength was to raise its power supply voltage. As it turned out, I needed to increase the voltage to 42V for it to be strong enough.
Why doesn't the electromagnet burn out? It only operates for a very short time, and for most of the time, it's inactive. Therefore, it doesn't have time to overheat.
Additionally, the electromagnet's activation time needs to be precisely controlled. For this, I used a 555 timer.
To determine when