[Laser] Laser on CDs XE2AT

[Art]

Hi Al,

The photodiode in a cd player is a very small active area, you will have=20
trouble focusing your light on such a small rx surface area.

It is also a high frequency unit, with response to several tens of Mhz, it=
=20
will not perform well for detecting weak signals at narrow bandwidths. It=20
might be usable for very wideband signal reception, such as video. If the=20
feedback resistor is accessible, you can convert it to a wider bandwidth,=20
but this might be impossible as they are often enclosed in the package or=20
they are simply 50 ohm resistors and a PD, with the output fed into an RF=20
front end directly (no transimpedance amp used at all).

Keep in mind that there are 4 such photodiodes and 4 amps. Sorting them out=
=20
might not be easy.

On the newer cd players, these are integrated into the splitter module that=
=20
has the transmitter on one port and the multichannel receiver on another=20
port-you can't get good access to the electronics to modify it. But, it's=20
cheaper to build and requires no alignment...so it's the preferred method=20
today.

The laser diode might be anything, visible or IR. In the older read only=20
drives, they are 1 milliwatt types. In the newer read-write drives, they=20
could be up to 30 milliwatt output.

Wish there was a better answer, but it's hard to tell by long distance.=20
Laser Sam's FAQ has a whole section on CD units, including an explanation=20
on how they work and how to salvage parts from them.

Regards,

Art




At 10:53 AM 2/17/04, you wrote:
>GM all I have a very old CD player and I saw a chip like OP210 , the=20
>diference is it have 10 pins( but just 8 used ), somebodie know about it?
>I can use it for a Laser receiver ?
>  I can use the G0MRF diagram like the used for Op210 ?
>Thanks in advance
>Al
>XE2AT
>   and the Laser used on CD how many mw have ?
>
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