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Voltage Limiting Circuit for Codec



Jan 1, 1970
Hallo again all,

You might not remember, but a few months back you guys helped me
design a photoreceiver, as outlined here -

I've been using this circuit ever since with no problem to report -
thanks again. I'm now at the stage though where I need to connect this
circuit to the Codec on my DSP board. The codec specs are here, (the
evm is an evaluation module for the aic23 chip which I'm using as a
daughterboard for my dsp motherboard) -

In order to protect my Codec, I've come up with the following limiter
circuit (as an adition to my origional receiver) -

This circuit limits the output voltage to between 1.5 and -1.5V.
Ignore the LM324 - its readily available in PSpice, but I would use
the LF353 instead. The codec line input takes 1 Volt RMS. In my
limiter circuit, the current source again represents my photdiode.
I've excluded the rest of the origional reciever circuit, such as the
2222 in order to simply things.

Is this a reasonable design?

What value of resistor should I place between the op-amp's output and
the codec's input?




Jan 1, 1970
My server is going down alot of late - MyDoom related perhaps. I've
therefore copied my stuff to a geocities page also -

under the heading - "Limiter Design" on that page.

The final circuit I've presented on that page is the circuit I'm
planning to interface to my codec. First of all, have I designed this
final circuit correctly? Sould I connect the opamp output directly to
the ADC, or should there be a resistor between them? What would its
value be? And should I include a cap also to high-pass filter any high
frequency noise?

Thanks for your help,