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I have managed to produce a design within the falstad circuit simulator for an analogue "LED chaser" using an analogue multivibrator and 3 comparators inspecting the voltage of one side of the multivibrator.

Once I had completed it I decided to link all the circuitry to one supply (the pullups for the comparators were originally fed by a separate 5v supply) thinking this would alter the output waveform; it didn't (to my knowledge).

If I were to make this circuit in real life would there be any disadvantage to using a single supply? Please excuse this if it is a fundamental/beginner sort of question I am not academically trained in electronics

The circuit link is here (cannot produce schematic from simulator)

circuit screenshot

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    \$\begingroup\$ Just a suggestion - if you flip the comparator inputs so that comparator out Low = LED on, and connect the LEDs between +5V and the comparator output, you will save three resistors, and can easily drive the LEDs with more current by reducing the resistor value (max currrent determined by the comparator output capability). \$\endgroup\$ – Peter Bennett Sep 2 '18 at 22:50
  • \$\begingroup\$ That does work, thankyou for the suggestion! \$\endgroup\$ – Scott Anderson Sep 3 '18 at 15:00
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Usually you power everything in a circuit from the same supply voltage, unless you really need different voltages for different parts of the circuit. Since your circuit only needs 5 volts, you can of course power everything from a single 5V supply.

Think of it like a power bar: You can plug in as many devices as you want (as long as you don't overload it, of course).

Your circuit needs so little power that overloading your power supply is not a concern.

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If you want low-edge-jitter, there will be an advantage. Otherwise, don't worry.

Given all VDD networks have Caps and inductors (wires), there will be resonances with ringing triggered by the comparator demands for charge.

Unless the VDD ringing is well dampened before the oscillator does the next level switch, the précising timing will be perturbed.

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