Early relaxation oscillators were commonly designed with inverting transistor gain stages using the same basic topology as the grounded or Vcc referenced inverting bicore. The non-inverting Rigter bicore circuit in Figure 6 shown side by side with the classic inverting grounded Bicore is actually quite unusual. It can use non-inverting buffers such as the 74HC244 or 74HC245 with one grounded and one Vcc referenced resistor. In both bicores, the duty cycle of the output pulses determined by the ration of R1/C1 and R2/C2 time constants. The non-inverting bicore lacks the complementary (inverted) output which makes it somewhat less versatile.Yet it provides an option for designing an oscillator using some spare non-inverters rather than adding another inverter chip.
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