I am not expert,
But i use my tiny brain for making some thing.
Will this work???
OR
There is any mistake in it???
Some improvement???
And second,
I make this circuit in "ExpressSCH" now i want to make it's PCB in "ExpressPCB" but i don't know how can i open this circuit in "ExpressPCB"...
Plz guide in..
The high current from the 555 will probably destroy the laser and the 555 without a current-limiting resistor.
Your photo-transistor is an emitter-follower without any gain. Use a collector resistor and ground the emitter to get some gain out of it.
To be pickey it's pulse position modulation and you can't easilly frequency modulate a laser. Only pulse frequency modulation is easilly possible. Frequency modulation requires a special type of laser and reciever and is at the cutting of technology at the moment.
Sorry, I stand corrected. It does use pulse-position-modulation and its average level will be audio after the carrier is filtered out.
It will pickup AM interference like AC lamp buzz.
A laser or anything else that can pulse can have its carrier frequency modulated with FM. It is difficult to modulate the colour of a laser with direct FM modulation.
That can be minimised by filtering, a 50/60Hz filter might help but then you'll still have the harmonics. A comparator with some hysteresis might help but that will effect the sensitivity of the circuit. The best way to remove the interference is to use a higher frequency like 38/44kHz and a TV remote control IC for the reciever.
Another Problem,
PhotoTransistors are not available in our local market.
Only the PhotoResistors(LDRs) are available.
I want to replace PhotoTransistors with PhotoResistors... Plz guide me in this way
Thanks
I'm quite confident it will not work with LDR/CDS cells (photo resistors). They are too slow. Order phototransistors online, catalogue shop, from eBay etc, they are generally common.