Personal Alarm Transistor Pair

From the following diagram:
**broken link removed**

What is the purpose of the transistors in this circuit? I understand that a transistor in general can be used to amplify a current/voltage but what are its functions in the above configuration?

For reference, the circuit is taken from:
How to build Personal alarm - circuit diagram

Thanks, forum.

It is an astable multivibrator (square wave oscillator) which oscillates only when the switch is open. It is a crummy design, it that it will kill the battery just sitting around waiting for someone to open the switch.

MikeMl said:

It is an astable multivibrator (square wave oscillator) which oscillates only when the switch is open. It is a crummy design, it that it will kill the battery just sitting around waiting for someone to open the switch.

Click to expand...

No.
It draws only a small current through R1 when it sits around waiting for someone to open the switch.