I'm building a voltmeter based on the ADC and seven segment display driver chip CL7107.. However it needs a dual supply of +/-5v.. What is the simplest possible way to make a negative strip from a positive one?? Also if I use a transisor inverter will it affect its working as this chip depends on the symmetrical pulse of supply.. The data sheet also specifies an easy way of using cd4009 and 2 IN914 diodes and 2 caps.. can i use a 1n4001 diode instead??