automatic dark sensor

[antsoua]

Hi, please help! I would like to make an automatic dark sensor using AC(220v), the lamp has a bridge diode included, can this circuit works perflecly with the corresponding values?

 

[davenn]

no
that is VERY dangerous
use a low voltage source for the LDR and transistor circuitry and use it to switch a 220VAC rated relay or preferably a SSR ( Solid State Relay)

 

[antsoua]

I've tried to seperate both circuits by using an optocoupler and a 9v DC for the switching circuit! Is the configuration and values of this OK?

 

[antsoua]

PLEASE NEED HELD!!

Automatic Night Light (outdoor)

1- my 5watt 68k resistor heats too much! i have tried to lower the heat by putting 3 of the 5w 68k in series, that was ok! however when i connect the load the output voltage dropped!! please what what can i do to settle it?

2- my second issue is the HYSTERISIS, the system is not able to actuate the relay

 

[Alec_t]

That is a potentially DANGEROUS circuit which could kill someone. It also has errors. You should use an isolation transformer.

 

[Harald Kapp]

This circuit again works directly from mains. As @davenn said, this is dangerous. Your post #3 shows a much safer configuration. You'll have to add hysteresis to avoid blinking of the light at dusk and dawn.
Have a look at this circuit.

 

[duke37]

A resistor across C2 will dump some of the input current and reduce the dissipation in R3 and the Zener.
Replacing R6 with a Zener will increase the amplifier gain.
Investigate the effect of R5 and R7 to get it to operate the switch.

Do your experiments with a 9V battery.
I do not see the purpose of R4.
I see no hysteresis although some would be a good thing to give a snap action.

Some data on the optoisolator would be helpful.