Bandpass filter help

[lucasfru]

Hi!
I'm currently trying to make 2 microcontrollers communicate using a laser laser diode and a solar panel.
The problem I have is that I cannot manage to make serial data go from µc1 to µc2, a friend of mine suggested to use a bandpass filter but since I'm kind of a newbie in electronics and nobody I know irl seems to be able to help me I'm posting here...
I want to make a 9.6khz bandpass filter, I dont understand the notion of gain, what should I use ?
I have lm358's and lm324's at home, I would prefer to use 324 but any help would be appreciated !
Thanks in advance!

 

[BobK]

A solar panel is the wrong detector to use with a laser diode. You want a phototransistor. Or, better yet, you want device like the TSOP4838, which has the detector plus processing to recognize a specific frequency (38KHz for that part number) These are way better than what you would be likely to build.

How far do you need to transmit? If not more than a few meters, a simple IR led would work. If not an IR laser pointed right at the detector would work. The emitter must be driven by square wave at the matching frequency.

Bob

 

[Audioguru]

The lousy old LM358 and LM324 opamps have poor slew rate which causes trouble with frequencies above 2kHz. Instead use a more modern opamp that works fine up to 100kHz.

Gain is the amount of voltage amplification. An active filter needs only a certain amount of gain so that it has sharp and steep filter slopes without oscillating.