Great i try to build in on pcb. Just one question if i want to use ziner diode as stable 3VDC supply how can I do that with current circuit?
Thanks

Why do you need to do that?
The circuit is designed for using the 4.5volt output on the DC adaptor you listed.

 

Why do you need to do that?
The circuit is designed for using the 4.5volt output on the DC adaptor you listed.

I want to put dc adapter at 12VDC (full voltage) so thst i can power any voltage devices in future. So if i want to for instance add 12v or 6v or even 5v lights or devices i can.

 

So use a voltage regulator. A zener is a very poor regulator.

 

I want to put dc adapter at 12VDC (full voltage) so thst i can power any voltage devices in future. So if i want to for instance add 12v or 6v or even 5v lights or devices i can.

Why do you need to do that?
The circuit is designed for using the 4.5volt output on the DC adaptor you listed.

Do you know how to modify circuit to include it?

 

So use a voltage regulator. A zener is a very poor regulator.

Without ics or relays as usual please

 

Do you know how to modify circuit to include it?

Why not operate those lights on a separate 5 volt USB charger? They are not expensive
At 5 volts change R2 to 37K and R6 to 18 ohms at .5 watt

 

Why not operate those lights on a separate 5 volt USB charger? They are not expensive
At 5 volts change R2 to 37K and R6 to 18 ohms at .5 watt

I dont have usb charger. I have only one 120V vac outlet outside where landscape light is going to be thus the adapter

 

This is the original circuit modified to operate on 12 volts.

 

This is the original circuit modified to operate on 12 volts.
View attachment 331235

Can you briefly explain how the circuit works?

 

Same circuit but using the zener as a regulator to control the bias on Q1 so the tripping point remains at 0.5 volts

 

Same circuit but using the zener as a regulator to control the bias on Q1 so the tripping point remains at 0.5 volts

How do lights get 3V??

 

How do lights get 3V??

R6 drops the voltage to 3 volts across the LED

 

Same circuit but using the zener as a regulator to control the bias on Q1 so the tripping point remains at 0.5 volts

I dont follow how?

 

In order to operate at 12 volts there are several design modifications one can choose from.
I chose to use a zener diode to maintain a constant voltage source for the bias on Q1 which is critical in order to maintain the trip point at 0.5 volt with the value of R2 listed.

 

This is the original circuit modified to operate on 12 volts.
View attachment 331235

Why the capacitor in parallel? Also it take 20 ma for zener diode to operate

 

Doesn't take 20 ma to operate a zener diode.
The cap is a dc filter.

 

Doesn't take 20 ma to operate a zener diode.
The cap is a dc filter.

I dont have any ac. All is dc. I dont get what you mean capacitor filters dc?

 

I dont have any ac. All is dc. I dont get what you mean capacitor filters dc?

There could still be a small amount of ac ripple in the power supply output. The cap helps reduce that somewhat.

 

There could still be a small amount of ac ripple in the power supply output. The cap helps reduce that somewhat.

Is this circuit practical? Meaning you built it and it actually works or is it something in drawings and doesnt work in reality?

 

It works as designed.
The question is, are you actually going to build it or go on asking questions forever.