Controlling lights with laser gun like mr bean

I have made a very simple circuit that can be made under $3 and is operated with the help of laser light... Mr. bean used a gun to turn off the light bulb. So, I hit upon a plan and made a simple laser gun and a very small circuit to control the led lights and turn them or on off without use of any microcontroller like Arduino etc.

Components:

LDR--2

Transistor BC547 ---1

Traic MCR 100 ---1

3 Resistors 1k

4 Volt battery

Working:

it has two parts basically the first part is used to turn the lights off while second part is used to turn light off. I have demonstrated it on my youtube Video you can go and check it out by yourself

Now, the first part contains a triac MCR100 which is a triac, it is bit different from transistor as it can allow the flow of current through it even if base current is cut off.....so I used one ldr connected to +5V and other leg at base of triac(MCR 100) while 2k resistor with the base of triac and other leg is with ground. So when the laser light falls on LDR its resistnace gets low and Triac gets ON. while when laser light is removed it still gets on as it allows the current to flow even when base current is cutt off....

Second part consists of BC547 Transistor, which contains an LDR_and_resiistors, when light falls on it it actually cuts off the current so resistors are connected with +5V while the LDR is connected with theground so in darkness its resistance is high and hence current flows but when light falls on it it actually turns it off!

Now, I have taken wire from the output of the second part (from the emitter) and connected it with the first part (with the collecter of MCR 100), so when we apply light on first part it actually starts the current flow and when light falls on second part it cuts off the current to the collector and turns it off...........

if you are having difficulty in understanding go and check out the the video link is again given here.

https://www.youtube.com/watch?v=GEpFrA-GQAk