Electronics for Audiophiles: Voltage and Current (Video)

[Doodski]

I was told the real thing killing you is a given amount of current reaching your heart.

From that basic point it goes that a little voltage applied directly on flesh (very low resistance) being exposed through a cut in the skin (high resistance) could certainly kill you.

Since high voltages can overcome the resistance skin have, the general idea people do remember is only high voltages are dangerous.

I took a hit from a 1KVA toroidal with large smoothing capacitors charged up to ~+/- 68VDC right across the base of the triceps muscle at my elbow. The muscle in my arm deflected and my arm brought my hand to my face and smacked me enough to bend my glasses and leave a red welt on the side of my face. I could have broken my nose or the forearm if it generated enough force and impacted a object. So not sure if I took one of the ~68VDC rails or both rails for a total of ~136VDC.

 

[F1308]

I took a hit from a 1KVA toroidal with large smoothing capacitors charged up to ~+/- 68VDC right across the base of the triceps muscle at my elbow. The muscle in my arm deflected and my arm brought my hand to my face and smacked me enough to bend my glasses and leave a red welt on the side of my face. I could have broken my nose or the forearm if it generated enough force and impacted a object. So not sure if I took one of the ~68VDC rails or both rails for a total of ~136VDC.

For me, anything above 1.5 volts is frightening.
I could move that point up to 12 if you need me to, but not any further, as recharging the 12V batteries in any of my cars do call for checklist carried out before starting such a high-risk task.

 

[Addicted to music]

Well done on another explanation on basic Ohms law and power supplies. I’m glad you mentioned that amplifiers are basically whats referred to as a voltage source, this is super important to all the claims on another forum claiming that amplifier designers have no idea due to the impedance curves of loudspeaker curves! Some of the BS that’s out there and they argue till they are blue in the face!!! There are also many who believe that Linear PSU are far superior than any SMPS, unfortunately in this day and age it’s the opposite and some SMPS are far superior than Linear.

 

[Addicted to music]

Don’t try this at home Folks……

 

[aatoma]

To be honest iam not so happy with the video.

I think it would be better to stay for the first video just with voltage, current and resistence. Its not right that the voltage kills you, its the current through you body that kills you. That you can thouch 24V is coused by your high body resistence, that limits the current. Understanding how voltage, current, resistance interact is the A in the abc. I know that sounds like critisism for nothing. But its so importend imo to get it right from the beginning. Static has a very high voltage but does not kill you, couse it delivers not enough current.

In the same boat. I especially found confusing the way current was introduced: 'touch a 300 amp battery' might let someone think that you can safely touch a source causing your body to be traversed by a 300 amp current. Such a source (a very high voltage source) would kill you the same way a car battery can melt a conductor which, due to its low impedance allows it to output all the current it can. Also 'too much current is fine' is misleading: if your device requires 5V to work, and you connect it to a power supply capable of generating an infinite amount of current it will only draw the currrent needed by its internal working. But if the same device for some reason (malfunctioning) starts drawing one hundred times its nominal current, theres no way this is going to be fine. Voltage is voltage even if no current flows, current is current only if it flows. The video is otherwise super helpful, I think, we need to strike the right balance between correctness and simplicity

 

[sarumbear]

I am starting a new educational series on simple but essential engineering concepts/lingo we use in discussing audio products. This is the introductory video on voltage, current and power supplies:

Please give feedback as to whether you find this type of video useful and I will make more of them.

Thanks.

I believe in little knowledge is a dangerous thing. I think such over simplification of EE principals will confuse people more than educate them. You will have ad infinitum of arguments on trivial things while they are completely missing the general principals.

 

[Doodski]

I believe in little knowledge is a dangerous thing. I think such over simplification of EE principals will confuse people more than educate them. You will have ad infinitum of arguments on trivial things while they are completely missing the general principals.

Principles of electricity is a ~1400 page full size textbook plus a lab book too. Fundamentals is another 2400 pages plus 2 lab books. If we are talking walwarts then lets call it what it is a walwart basic power supply and not fundamentals of electricity.

 

[ZolaIII]

Effects of Electrical Current on Heart Rhythm​

In short reading.

Effects of Electrical Current on Heart Rhythm | Howard M. Hochberg | download

Effects of Electrical Current on Heart Rhythm | Howard M. Hochberg | download | BookSC. Download books for free. Find books

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[tomtoo]

Principles of electricity is a ~1400 page full size textbook plus a lab book too. Fundamentals is another 2400 pages plus 2 lab books. If we are talking walwarts then lets call it what it is a walwart basic power supply and not fundamentals of electricity.

But for understanding many things in hifi you need just two formulars.

U=R*I
P=U*I

With this you can go from your wall outlet, thru the amps, stright into your speakers. Yes ac makes it harder, but the princips stay.

 

[Scot_Douglas]

@amirm Thank you very much for doing this!

 

[Doodski]

But for understanding many things in hifi you need just two formulars.

U=R*I
P=U*I

With this you can go from your wall outlet, thru the amps, stright into your speakers. Yes ac makes it harder, but the princips stay.

Don't know what you are trying to communicate.

 

[tomtoo]

You can not talk about U and I without R. It makes no sense.

 

[tomtoo]

Don't know what you are trying to communicate.

U=V iam german.

 

[Doodski]

U=V iam german.

Yes, I remember from a video that Germans use U for V or E.

 

[tomtoo]

Yes, I remember from a video that Germans use U for V or E.

Than you should know what i try to communicate??

 

[Doodski]

Than you should know what i try to communicate??

Yes, you are mentioning the principles of electricity. Using the proper formulas and terms. I think that watering down the terminology makes the study less serious. As I mentioned in post #27.

 

[tomtoo]

You can not talk about U and I without R. It makes no sense.

See mathematians maybe enjoy divisions by zero. Electricians hate them, usually they mean destruction.

 

[JayGilb]

Very useful video. I like the content.

Maybe have links to these instructional videos in all of your equipment reviews so people have a quick reference.

 

[Martinvb]

Very educational Amir, thanks! Even a basic understanding of these things can be expanded when applied in a specific context, like audio.

 

[Lambda]

So saying V=R*I instead of U=R*I is like ordering 3 beer like this:

The more you know