Dual-Supply Comparator / Operational Amplifier - RC Astable Multivibrator

This is a nonlinear, RC relaxation oscillator using a comparator or an operational amplifier, the circuit is for dual power supply operation. When using a comparator, the circuit shown is for push-pull output drivers. For open-collector/drain output comparators a pull-up resistor from the output to the positive supply is needed. The pull-up resistor provides the charging path for the capacitor. If differences in timing relative to the circuit shown is to be minimized, the pull-up resistor should be as low as possible. Low frequency of operation could necessitate the use of electrolytic capacitor. For polarized capacitors the negative terminal should be connected to the negative power supply of the operational amplifier instead of to the GROUND.