MK111 low voltage question

Hi, first of all let me say that I am absolutely thrilled that velleman would host a forum for its products, and fosters the DIY culture. Anyway, I have a problem/question with the MK111 kit. I have built it and it works fine. I have been successful in substituting the relay with a transistor and some resistors so that the package is solid-state (and draw less power). However, I am wondering if there is a way to make the kit works with a lower supply voltage, such as around 3V? I tried it with a 9V battery and that seems to work fine, but I would like to use 3V (i.e. 2 AA cells) because I have rechargeables for those but not the 9V. I appreciate any input on this. Thank you very much!!

Tom

555 requires a minimum of 4.5V
Please note that 2xAA rechargeable only supply 2.4V and not 3V