Audio Amp Power (+12V, -12V, and Ground)

[DrChek]

I just need someone to confirm my non-IEEE conclusion...

It wont be possible to power this amp...


...via a computer power supply MOLEX connector because of the lack of a -12V source.


TRUE or FALSE?

[brad808]

It is possible, you may get lots of noise in the signal though. That's the problem i had and went back to a wall wart.

The computer has +12v and ground and that's what the amp needs. Not sure where you are seeing the -12v.

Sent from my Desire HD

[DrChek]

Not sure where you are seeing the -12v.

I assumed that the - on the ring of the power connector meant -12V. Not right?

[brad808]

The little diagram is showing the outside of the connector is ground and the inside pin is 12v. So before you plug it in test with a voltmeter with black terminal on outside ring and red terminal inside the hole. Should read +12v.

Sent from my Desire HD

[DrChek]

The little diagram is showing the outside of the connector is ground and the inside pin is 12v. So before you plug it in test with a voltmeter with black terminal on outside ring and red terminal inside the hole. Should read +12v.

Sent from my Desire HD

I guess that's one reason I never understand circuits. I would have thought they'd use the ground symbol or a 0 to indicate that. 

[jezz]

What that symbol indicates is a 12V voltage between the pin and the shield.

Electronics started to make a lot more sense to me when I started to think of electricity a bit like altitude above sea level. Say you have a need for a 10m waterfall. Sure, you could accomplish this by dumping water into the ocean from 10m above it, but you could equally accomplish it by going from 1000m above sea level to 990m above sea level. For the purposes of this analogy, the difference in altitude is "voltage," and the ocean/sea level is "earth ground."

Incidentally, current and resistance also work in this analogy. Electrical current is analogous to water flow rate, and electrical resistance is analogous to restricting the water flow by some mechanical means (like putting your finger on the end of a water hose).

So that particular circuit needs a 12V difference to function, and some unknown current requirement (I'm guessing that's a Lepai TA2020A+, which uses 6A@12V or 72W, so make sure your power supply can provide that on the 12V rail).

[DrChek]

I understand voltage, and use an analogy similar to what you describe, but what threw me is the minus (-) sign. The mathematician in me saw that as -/+ 12V which is not a 12V difference.

What that symbol indicates is a 12V voltage between the pin and the shield.

Electronics started to make a lot more sense to me when I started to think of electricity a bit like altitude above sea level. Say you have a need for a 10m waterfall. Sure, you could accomplish this by dumping water into the ocean from 10m above it, but you could equally accomplish it by going from 1000m above sea level to 990m above sea level. For the purposes of this analogy, the difference in altitude is "voltage," and the ocean/sea level is "earth ground."

Incidentally, current and resistance also work in this analogy. Electrical current is analogous to water flow rate, and electrical resistance is analogous to restricting the water flow by some mechanical means (like putting your finger on the end of a water hose).

So that particular circuit needs a 12V difference to function, and some unknown current requirement (I'm guessing that's a Lepai TA2020A+, which uses 6A@12V or 72W, so make sure your power supply can provide that on the 12V rail).