Hey all, got a confusing (for me) one...on 41hz.com, in the AMP3X writeup, halfway down the window it clearly shows the AMP32-PS top and bottom describing the Voltage input.
Keep in mind this is the AMP32-PS - with a power supply onboard. You can see the Full Wave Bridge Rectifiers and the Smoothing Caps. The question is it says it can take a AC or DC power connection to this on board power supply.
What happens when you send DC into a Bridge Rectifier/Smoothing Caps arrangement? Do you get a square wave AC or is it still rectified DC?
I saw this and couldn't leave it alone...maybe one of you EE wizbangs out ther can confirm this is possible or is a mistake?
If it is possible, I have tons of 20VDC 3.5 Amp laptop power supplies I would love to be able to use on a few Gainclone and Tripath amps...
Keep in mind this is the AMP32-PS - with a power supply onboard. You can see the Full Wave Bridge Rectifiers and the Smoothing Caps. The question is it says it can take a AC or DC power connection to this on board power supply.
What happens when you send DC into a Bridge Rectifier/Smoothing Caps arrangement? Do you get a square wave AC or is it still rectified DC?
I saw this and couldn't leave it alone...maybe one of you EE wizbangs out ther can confirm this is possible or is a mistake?
If it is possible, I have tons of 20VDC 3.5 Amp laptop power supplies I would love to be able to use on a few Gainclone and Tripath amps...
I'm no expert, but I believe when you send DC through a bridge rectifier you just end up with the same DC minus the voltage drop of the diodes.
thats what happens.
the reason to use a full bridge rectifier with DC sources are:
1.) potential to use supply with DC or AC source.
2.) prevents current flow from load to supply.
3.) connects the DC supply to the load in the correct polarity.
the downside for the DC case is the extra losses in the diodes.
the reason to use a full bridge rectifier with DC sources are:
1.) potential to use supply with DC or AC source.
2.) prevents current flow from load to supply.
3.) connects the DC supply to the load in the correct polarity.
the downside for the DC case is the extra losses in the diodes.
Alternatively, you don't have to use the rectifier at all. Just jumper in your DC power and ground to the appropriate through holes where the rectifier would go.
So I can use two Laptop Power supplies - one to the rectifier for the positive rail, and one to the rectifier for the negative rail, and connect the grounds of both power supplies for the centertap...
As I said, I have many of these that I was just going to throw up on ebay for $5...now I can use them for a +/- 19V 120VA power supply...perfect for a low power gainclone or parallal a few more (four for around 400VA?) to use for my Amp5 I have yet to build...
As I said, I have many of these that I was just going to throw up on ebay for $5...now I can use them for a +/- 19V 120VA power supply...perfect for a low power gainclone or parallal a few more (four for around 400VA?) to use for my Amp5 I have yet to build...
BWRX - yes, I see what you are saying, but I would have to connect the DC upstream of the Reservoir caps, as I doubt these laptop power supplies have any...
I'm not sure what you mean by "upstream" but the large electrolytic caps will be connected to the supply rail and ground no matter what, so it technically doesn't matter where you jumper in DC on the board. I would remove the rectifier and use those through holes because that's the best place to do it.
john65b said:
AMP9.....
41hz.com....
Works fine on lower voltage...don't know about the 3.5A issue though..
Is this peak or nominal?
john65b said:
Very unlikely. Both supplies will be referenced to ground so connecting the positive of one to the ground of the other will be a short circuit.
BWRX said:
Technically you are right, but it would be bad in practice to not have your filter capacitors connected 'upstream', between your supply and load. Else, the ripple current that your capacitors are meant to be filtering will cause voltage ripple on your amps supply. Most significant for long leads or high frequencies.
Gorilla said:
The large cap is connected directly to the rectifier, so if you jumper in DC at the rectifier location the large supply cap will be between the external supply and the chip which, as you said Gorilla, is the best place for it.
Gorilla,
I would be connecting the grounds of both power supplies together to form teh centertap and the two 19VDC leads to the AC input of the rectifier to get the pos/neg rail voltages. I would not be connecting them in series.
I would be connecting the grounds of both power supplies together to form teh centertap and the two 19VDC leads to the AC input of the rectifier to get the pos/neg rail voltages. I would not be connecting them in series.
Actually, the other way around - connected the +20VDC of one laptop Power Supply to grnd of the other laptop Power Supply and now have a 20 0 -20 power supply.
It did not short and works fine...I had to correct myself from so many years back....
It did not short and works fine...I had to correct myself from so many years back....
Putting dc through a full wave bridge rectifier? At the least you should have reverse polarity protection. Right? The ones with 4 IC shave low voltage drop .1 v . I ordered one from China for 3.00. That drop beats diodes or Schottky diodes by far and very low power dissipation!
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