Hi All,
I've got a couple of no name branded photocell or day/night switches. They run from mains and give you a switched live output. I've drawn this schematic from the PCB itself.
My questions:
1: What purpose do R7, and the RC circuit comprising R8 and C1 serve on the AC side of the rectifier?
2: What are R2, R4, R5 and C3 for? I think R2 is for keeping the base of Q1 low and R4 maybe limits the base current, but I'm not certain.
3: Zener diode ZD1 is a 4V diode that (I think) gives you 4V once the Phototransistor gets enough darkness to bring the voltage from divider Q3,R6 high enough to reverse bias the diode above 4V, allowing it to conduct. Is that correct?
As you can see, ZD2 is a 24V diode, so the circuit essentially runs from 24VDC. The relay is also 24V.
Thank you for your help.
I've got a couple of no name branded photocell or day/night switches. They run from mains and give you a switched live output. I've drawn this schematic from the PCB itself.
My questions:
1: What purpose do R7, and the RC circuit comprising R8 and C1 serve on the AC side of the rectifier?
2: What are R2, R4, R5 and C3 for? I think R2 is for keeping the base of Q1 low and R4 maybe limits the base current, but I'm not certain.
3: Zener diode ZD1 is a 4V diode that (I think) gives you 4V once the Phototransistor gets enough darkness to bring the voltage from divider Q3,R6 high enough to reverse bias the diode above 4V, allowing it to conduct. Is that correct?
As you can see, ZD2 is a 24V diode, so the circuit essentially runs from 24VDC. The relay is also 24V.
Thank you for your help.