I learned from Morgan Jones Valve Amplifiers that the min current required for choke input is approximately equal to Vin(rms) divided by L(H). That means as the current is lower the induction has to be higher. I wonder if this formula still apply if chokes are in series and using the total induction summed up??
That approximation for minimum load current relates to a simple LC filter. You can use any parallel/series connection of inductors you want, but you then need to calculate the equivalent L of all the inductors. So yes using two inductors of the same inductance 1H, and connecting them in series, will give an equivalent L = 2H.
Note that commonly used chokes have an inductance that could easily change by 10-20% between the minimum load current (to meet the 'continuous conduction' aim of the diodes) and the max rated current. Also note that most chokes are designed only for CLC smoothing applications, and you would need to confirm that a choke is actually rated for an LC smoothing application.
Note that commonly used chokes have an inductance that could easily change by 10-20% between the minimum load current (to meet the 'continuous conduction' aim of the diodes) and the max rated current. Also note that most chokes are designed only for CLC smoothing applications, and you would need to confirm that a choke is actually rated for an LC smoothing application.
An easy formula for 60Hz mains power, full wave rectification (120Hz), and choke input filter:
Critical Inductance = 350/mA load.
Example, 70mA load:
350/70mA = 5 Henry.
Use a 7 Henry choke to have a little safety margin.
For 50 Hz mains, full wave rectification (100Hz), then . . .
Critical inductance = 420/mA load.
420/70mA = 6 Henry
Use 8 Henry to have a little safety margin.
Critical Inductance = 350/mA load.
Example, 70mA load:
350/70mA = 5 Henry.
Use a 7 Henry choke to have a little safety margin.
For 50 Hz mains, full wave rectification (100Hz), then . . .
Critical inductance = 420/mA load.
420/70mA = 6 Henry
Use 8 Henry to have a little safety margin.