Using Choke in LCRC filter in power supply

[vangogh-hk]

In my power supply for a ground grid pre-amp; I use bridge diode rectifier and LCRCRC filter.
Could any one told me if I using a choke of 10H - 200mA in a LCRCRC filter supplying a load requiring only 10mA. Will there be any problem.

i.e. What is the drawback of using a choke with much higher current rating than required?

Thanks

 

[amperex]

The choke will not act as a choke input unless Icret is met. Icret is when enough current is drawn in that the capacitor following that choke does not charge up to 1.4 x the choke input voltage. To meet Icrit, you will need more load (current) thru the choke with a large bleeder resistor. How about a new Hammond HC154G for $8.50 You could probally sell the large choke for more than that.

 

[vangogh-hk]

Thanks

How about if I change the choke input to capacitor input. Could the choke work in this case.

How could I determine the value of the Icrit if the rectifier output volatage is about 230V and the working current is about 8mA?

 

[Johan Potgieter]

It was mentioned in another thread some time ago (which I cannot trace now), that choke-input filters are not really used for pre-amps.

Firstly the choke needs to be of a minimum inductance inversely proportional to the current drawn as said, and secondly the normally low current needed and available B+ voltage make the use of CRC filters so much more convenient. And even if the designer is a perfectionist, high voltage semi-conductors for series elements are available at a fraction of the cost of a suitable choke, that can really reduce ripple to academic proportions.

There might even be high voltage IC regulators on the market, although I do not know of any. Are there?

 

[hagtech]

I use choke supplies for preamp. Many have done this. Size of choke is not prohibitive. For an easy way to calculate the choke you need, try this:

www.hagtech.com/theory.html#choke

jh🙂

 

[aletheian]

I use choke supplies for preamp. Many have done this. Size of choke is not prohibitive. For an easy way to calculate the choke you need, try this:

www.hagtech.com/theory.html#choke

jh🙂

WOW! Those are incredibly helpful calculators! Thatnx for the link.