I have an original circuits as follows:
View attachment 100838
Figure 1 original circuit
View attachment 100839
Figure 2 12V supply circuit
The circuit in Figure 2 provide 12 V to LM258D amp. Input DIMI_L and DIMI_N are from flyback converter output as follows.
View attachment 100845
Figure 3 flyback circuit provides power input for the circuit in Figure 2
When I measured the pin 7 output at its original circuit in Figure 1, its output is dc voltage around 10.9V.
After I modified the circuits, which Q1 was replaced with 47K resistor and I put diode between pin 7 and the base of Q3. The output was as follows.
View attachment 100842
Figure 4 Modified circuit
Here is the modified circuit output, which is not my expectation.
View attachment 100844
Why does its output perform like this way, not dc voltage output? How does this happen? I don't know if this saturated and the top was cut since this is very big output gain. LM258D Datasheet is attached.
Thank you for your help
View attachment 100838
Figure 1 original circuit
View attachment 100839
Figure 2 12V supply circuit
The circuit in Figure 2 provide 12 V to LM258D amp. Input DIMI_L and DIMI_N are from flyback converter output as follows.
View attachment 100845
Figure 3 flyback circuit provides power input for the circuit in Figure 2
When I measured the pin 7 output at its original circuit in Figure 1, its output is dc voltage around 10.9V.
After I modified the circuits, which Q1 was replaced with 47K resistor and I put diode between pin 7 and the base of Q3. The output was as follows.
View attachment 100842
Figure 4 Modified circuit
Here is the modified circuit output, which is not my expectation.
View attachment 100844
Why does its output perform like this way, not dc voltage output? How does this happen? I don't know if this saturated and the top was cut since this is very big output gain. LM258D Datasheet is attached.
Thank you for your help
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