Moved to 'Everything Else'.The opamp is configured as a simple inverting amplifier/mixer with a gain of 100k divided by 33k on each input (L and R). The input impedance is 33k.
The two diodes (which I assume were to be some kind of limiter) serve no purpose because there is never any measurable signal at that point... its a virtual earth mixer.
The circuit senses the output of an amplifier and actuates a relay to enable the speakers.
I think the diodes are to prevent damage to the opamp in case of overload due to fault conditions.
Andy
I think the diodes are to prevent damage to the opamp in case of overload due to fault conditions.
Andy
Of course it is not any sort of "servo". What does the sales-page call it?
It senses sustained DC from a Power amp and cuts-out a relay. Opamp gain is about 3. The inputs could be swinging 40V peak. Above 4V peak the "summing node" will be overwhelmed. While the TL0 input can take some abuse, the diodes are wise.
Q1 Q2 are a full-wave rectifier. Either + or - input here, over 0.6V (0.2V at amp) will turn-off Q3, open the relay.
C58 deemphasizes stuff over 2Hz (audio). C59 with 470k sets a 2+ second delay before cut-out to reduce false triggering.
It senses sustained DC from a Power amp and cuts-out a relay. Opamp gain is about 3. The inputs could be swinging 40V peak. Above 4V peak the "summing node" will be overwhelmed. While the TL0 input can take some abuse, the diodes are wise.
Q1 Q2 are a full-wave rectifier. Either + or - input here, over 0.6V (0.2V at amp) will turn-off Q3, open the relay.
C58 deemphasizes stuff over 2Hz (audio). C59 with 470k sets a 2+ second delay before cut-out to reduce false triggering.
That's only true when the circuit is on and doesn't clip. They are probably there to prevent damage when this isn't so.
> to eliminate dc component.
It disconnects the speaker when it sees "too much" DC.
"Too much" is roughly 0.2V for (I was *wrong* before) more than 0.2 seconds. (The 470k+100uFd is a turn-ON delay.)
0.1V of DC can happen forever.
A very strange condition: +1V on L and -1V on R will never be detected.
It disconnects the speaker when it sees "too much" DC.
"Too much" is roughly 0.2V for (I was *wrong* before) more than 0.2 seconds. (The 470k+100uFd is a turn-ON delay.)
0.1V of DC can happen forever.
A very strange condition: +1V on L and -1V on R will never be detected.