Help for IR detcting circuit

I am trying to do a circuit that detects object presence or absence using modulated IR rays(to avoid other IR sources) by using LM567 to modulate the IR-LED and to detect the reflected frequency , i got the circuit diagram and i understand the theory of operation but the problem is i don`t fully understand the details of LM567 and that makes some connections mysterious to me here is the circuit :
**broken link removed**
the VCO should produce pulses at certain frequencies that should force the LED to produce IR rays at same frequency then detected by phototransistor and entered to the chip to be compared to the original frequency if it is in the BW pin 8 should be low , I DON`T UNDERSTAND WHY THE CIRCLED THINGS ARE CONNECTED IN THAT WAY AND WHAT THEY DO??????
PLEEEEEEEEEEEEEEEEASE HELP.

I recommend getting a data sheet from National.

data sheet is not helpful i tried hard with it