Building a motion sensor circuit

Hey guys, im working at a schoolproject with a friend of mine where we are bulding an entire alarmsystem with several alarms and a central station which handles these alarms.

I am trying to construct a proper working motion sensor circuit and have found an idea with the use of IR diodes. Also I would like to include some ambient light filtration.

In the included file there is a sender circuit, which includes a timer circuit which sends impulses into a comparator. I have a diode connected in the right side which sends pulses of light out. This diode is connected to a voltage source so I can send some strong and powerful pulses without burning the diode out.

In the receiver part I have a narrowband amplifier and the circuit as a whole should filtrate the light away. I would like to say I have not made these myself but found the receiver and sender from different circuits and would like to put them together. I would like to hear your opinion about this setup and if it will work or you have some ideas which may make the circuit as a whole more easy.

Any help is appreciated, thansk

There's no point in having a comparator, the 555 can drive the transistor directly. It has a maximum output current of 200mA which is nearly enough for the IR diode.

so you think I can place the timer circuit itself instead of the part with the comparator so that the output of the timer goes into the transistor?

Yes, omit the comparator and connect pin 3 directly to R3.

do you happen to know a solution you can point me towards to solve the 12V, -12V problem in the receiver part?

How about using one of the IR remote-control receivers used in TV sets, etc. I used one for an IR beam-break detector, and was able to get a several feet range even in sunlight. They run on a single 5V supply, and cost about a $1.