I am looking for circuit that can hold dc volt for 5 sec when power off

Thread Starter


Joined Jun 13, 2018
Hi, everyone I am looking for circuit that can hold dc 110 volt for 5 sec when power goes down. Basically working on 3 phase motor and magnetic break system.when main power supply goes down break will activate which was working on dc 110 volt.so that any circuit will hold 110 volt for 5 sec even after main power switch off immediately break was activated and machine stops in its position.
Any help or suggestions?


Joined Aug 1, 2013
The question needs more details. Energy can be stored in a large capacitor, which is then discharged into the brake to keep it energized for a period of time. But in the most simple circuit, the voltage to the brake will decrease as the capacitor discharges.

1. What is the maximum voltage the brake can tolerate?
2. What is the minimum voltage the brake needs to keep braking?
3. What is the nominal current requirement for the brake?

With this information we can calculate the minimum capacitor size for the time period required. Note - it will be large and expensive.

If the brake needs a constant voltage, then you need to add a boost regulator circuit between the capacitor and the brake. Holding up the output voltage will decrease the capacitor more quickly, so you will need a larger capacitor than above.