What are these coil components with three legs?

Question

A couple of weeks ago I dissassembled a Panasonic DVD-recorder and salvage some components including these little guys. I tried to figure out what these are but cannot find a datasheet by searching for the numbers on these components.

I decide to crack on of them open (sse picture above) to see what's inside. There is a coil, looks like a decoupling coil. At the first place I thought this could be useful to seperate audio channels (ground-isolator) but the ground seems to be shared between coils. There are three legs, input, output and ground (I guess).

So what it is used for or what can it used for? Is there a datasheet of these things somewhere? The partnumbers are (numbers on the case of the component):

• CO 82
• CO 83
• B1 06
• B1 09
• 0 29

Answer 1

It's almost certainly a filter. Three terminal filters are common and popular, and can range from a tapped inductor, a pi filter, or an LCL filter depending. You'll likely find different values or topologies in each of those with different letters.

These are basically just potted inductors and capacitors arranged various ways, and can often be made just for a specific production run. Panasonic specifically is a large producer of these filters, so it makes sense that they would use custom parts produced just for one of their DVD drives. It's unlikely you'll find a datasheet, there probably was never a datasheet to begin with.

On the other hand, if you can measure inductance and capacitance, it is pretty easy to figure out the topology and frequency range of the filter.

Here is an example of what i mean:

They're really not much use and you can get any sort of filter you want in a nice SMD package these days off digikey anyway. But I am sure those are just potted filters. Not the most exciting answer, sorry!