earckens
Member
Hi, this diagram is for a detection circuit that does the following:
1. at the input a current transformer detects for the presence of 20kHz PWM signals. When these are present then Q1 is switched on
2. when detection is present the LED D5 should light up
3. when detection is present the relay output should be connected to +V through the P-channel Q4, and hence be activated.
However, as I read it, when detection is present then the output of Q2 goes high (no conduction because collector Q1 is low and thus Gate-Q2 is low); therefor Gate-Q4 is high and since this is a P-channel: no conduction drain-source, and the relay is off. Contrary to what it should be.
Is this reasoning wrong?
1. at the input a current transformer detects for the presence of 20kHz PWM signals. When these are present then Q1 is switched on
2. when detection is present the LED D5 should light up
3. when detection is present the relay output should be connected to +V through the P-channel Q4, and hence be activated.
However, as I read it, when detection is present then the output of Q2 goes high (no conduction because collector Q1 is low and thus Gate-Q2 is low); therefor Gate-Q4 is high and since this is a P-channel: no conduction drain-source, and the relay is off. Contrary to what it should be.
Is this reasoning wrong?