Low-voltage polyphasic circuits
Amplitude (arbitrary units) as a function of phase angle for two sinusoidal signals, 180° out of phase (dashed/dotted lines). The solid line represents the potential difference between the two dashed phases.
Microcontroller and second-order Sallen–Key low-pass filters, configured for split-phase or sliding-phase output. Pin numbers for the microcontroller and operational amplifier integrated circuit are italicized. For three-phase or four-phase operation, additional Sallen–Key filters are connected to pins 2 and 7.
Pinout diagram for the ATtiny13 microcontroller. Pins 1–3 and 5–7 are configurable as inputs or outputs. In the application described here, pins 2, 5, 6, and 7 are outputs and each is connected to a separate filter circuit, as shown in Fig. 2.
Output of a Sallen–Key filter acting on the square wave produced by the microcontroller (solid) compared to a sine wave of the same approximate frequency and amplitude (dotted).
Output of three Sallen–Key filters acting on the square waves produced by the microcontroller.
Circuit used for amplification of AC voltages prior to rectification.
Six-diode arrangement for full-wave rectification of a three-phase voltage signal. The sine wave inputs in this circuit are connected to the corresponding sine wave outputs in Fig. 2. A third filtering circuit would be added to the output labeled “Sqr Out 3” in Fig. 2 to produce the third sine wave output required here.
Four-diode arrangement for full-wave rectification of a single-phase voltage. is the voltage powering the amplifier.
Voltage across rectifier outputs for three-phase (solid) and single-phase (dashed) waveforms.
Schematic of the use of LEDs to illustrate a sliding-phase voltage. The relative phase of the two voltages changes slowly with time. The brightness of the LED connected across the two phases (left) slowly rises and falls, while the others (top, bottom) stay on at constant brightness.
Input-output map for selection of various polyphasic voltage schemes.
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