AC power outlet

[Kevin Weddle]

Does anybody have an explaination as to why the 5th harmonic in the 120Vac 60 Hz home outlet is so high? And is a battery voltage supply better than a conventional AC to DC power supply?

 

[Hero999]

1) It shouldn't be.

2) That depends on the power supply, a regulated power supply is much better than a battery.

 

[Kevin Weddle]

In all circumstances an AC to DC power supply is better than a battery? What about a battery with a voltage regulator?

 

[Alex Tsekenis]

I know some audio purists (also go by the name rich idiots by other people) use batteries to power their tube audio amplifiers. It is true that batteries will have lower noise than any other source. Adding a linear regulator will add more noise. Switching to batteries will be my last optimisation step in any audio project.

Not sure about the 5th harmonic as you say, could be anything, maybe your PC's power supply? Who knows. How big is it? Post a graph.

 

[Hero999]

Sorry buy that's total nonsense.

A battery will have a much higher impedance than a linear regulator.

A good amplifier will also have a high power supply rejection ratio so even if the power supply is noisy it won't make any difference.

The only time when noise can be a problem is when it's at high frequency, above the bandwith of the amplifier which can cause noise on the audio due to non-linearities in the amplifier. High frequency noise is only a problem if a switching regulator is used and can be mitigated by adding a filter or a low drop-out linear regulator; when the latter is used, the configuration is often known as a hybrid regulator.

 

[Alex Tsekenis]

Hero, by total nonsense are you referring to the fact that some people use batteries for their audio amplifier? From your post it looks like that.

 

[Hero999]

I mean anyone who says batteries are a higher quality voltage source than a linear regulator are talking rubbish.

Some audiophiles believe all sorts of rubbish ranging from scratchy old valve amplifiers sounding better than solid state amplifiers to gold plated oxygen free mains cable being better than ordinary cable. There are idiots who will spend

 

[Alex Tsekenis]

Wow. I hope no such "audiophile" falls in your hands

I couldn't agree more, I mean who cares about the fifth harmonic which will be better filtered by the bypass capacitors anyway. One of the extremes I have seen (can't recall where, prob some advert) is a silver/rubber ring to put around valves that "reduces noise and distortion by allowing electrons to travel smoothly from cathode to anode".  ???

Regarding batteries, they will have lower noise than any regulator, no matter how good it is. However, as you said, their high internal resistance makes them a bad choice for hi-fi audio.

 

[Kevin Weddle]

A battery can lose voltage, but it is probably better voltage regulation and a lot less noise than a conventional power supply. The problem occurs in the ripple output of the rectifiers. It's just a filtered varying voltage source.

 

[Hero999]

It depends on what you mean by a conventional power supply.

I assume you're talking about an unregulated power supply consisting of a transformer rectifier and capacitor?

If so you're right, a battery is better.

But if you're talking about a regulated power supply i.e. one made with an LM317 regulator, you're wrong it's far superior to a battery: lower impedance and better regulation.

Yet again, you haven't provided enough information.

 

[Kevin Weddle]

120Vac from the outlet is not a microwave signal. Regulators are linear. The circuit is non-linear.

 

[Hero999]

Why do you keep posting random comments?

 

[Kevin Weddle]

Power supplies are somewhat general purpose. Even though many electronics equipment utilize external power supplies, most have their own additional supplies which are designed for the product. It's only because the power supply might be inadequate for the circuit.

 

[Alex Tsekenis]

Hello Kevin,

If a normal person, not a general purpose silicon diode, has one bipolar transistor in each hand, and two capacitors on each foot how many components does the person have? Microwave magnetron voltage multiplier...

Thank you
Alex