Stephen Woodward has designed a novel 1 MHz linear voltage-to-frequency converter using the classic NE555 timer. The circuit builds on the familiar 555 astable oscillator by replacing the charging resistor with a current source for a more linear sawtooth waveform, then adds a carefully calculated resistor between the threshold and discharge pins. This extra resistor's time constant matches the 555's own switching delay, compensating for nonlinearity in the voltage-to-frequency curve. The result is a surprisingly simple yet genuinely new circuit from a chip that has been in use for over 50 years.
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