Slowly self-sustaining relay
If a capacitor is placed in parallel to the relais, a certain amount of energy is stored and the switch-on time is enlarged. The switching frequency can easily be adjusted by inserting different values on the capacitors. The capacitors store the electrical energy for a short time, even if the power supply is interrupted, so the relays deactivates if the voltage at the capacitor lower than the activating voltage of the relais. If the push button is pressed the rst relais is activated and the capacitor is also charged. After closing the contact, also the 2nd relais is activated and its capacitor is quickly charged. The 2nd relais interrupts the path to the ground of the rst relais.But the rst relais still gets some power throughs its capacitor in parallel. When discharged the rst relais is decativated and the 2nd relais interrupted from the main supply. But also the 2nd relais gets some energy from its capacitor which delays the decativation phase. If then the 2nd relais is deactivated, the ground connection to the rst relais is reestabilished and the whole processs starts again. This repeats until the push button is released. Note: Please pay attention to the correct polarity of the electrolytic capacitor! Try to test different capacitors.