The situation is this: I have an electronic door lock, that needs a bigger voltage kick to open, but after the kick, it can hold open with much less power.
The initial power needed to open is 9V @ 1,125A, but after that an 1V8 225mA is more than enough to hold the lock open.
I need to reduce power consumption (and heat generation), because after a few minutes the lock would overheat.
For this I tried using a huge capacitor (10 000uF) which deliveres the kick, and after that i reduce the voltage with a resistor (100Ohm, 5W). This works, but generates very much heat (the resistor dissipates around 0,8W, become really hot, even in open air, cannot put the circuit in a box with no ventillation.)
I would like to build a switching power regulator that generates 1V8 voltage, I could do this using for ex. a maxim MAX5035D.
But I would need a circuit that automatically switches between the power source once the capacitor has depletet its energy. (voltage drops below a certain voltage, not necessarily 1V8).
Can anyone help me with any links tips, or schematics on this?