rtarbell said:I recently ordered the LM4702 audio driver from National; it has a maximum supply voltage of +/-75V.
My current power supply will put out +/-80V. Is there any way I can drop about 10V for the 4702 in an efficient and cheap way?
depends on the power transformer you'll be using, and the final config of your lm4702 amps, could be that the +/-80volt rails will sag to 75volt levels once your amps is powered up and idling!
If your power supply consists of a toroid transformer, you could add several more turns on the transformer core and connect these to the primary windings. The wire should be of the same thickness as the primary. You should then insulate these turns with some insulation tap.
This is a non distructive alteration which will change the transformer turns ratio. NOTE make sure the new windings are in phase with with the primary.
This is a non distructive alteration which will change the transformer turns ratio. NOTE make sure the new windings are in phase with with the primary.
Which resister should I use for red circled place on the attached image
As I have 35VAC transformer , is this transformer suitable for this amp
The resistor is inside the darlington package already, you don't have to put in anymore stuff outside.
I hope you have a 230:35-0, 35-0Vac transformer.
You need a dual polarity supply for that amplifier and that requires 70Vac to get ±50Vdc
The pic in top right shows a 60V centre tapped transformer (30-0-30Vac). ignore the + they made a mistake. AC voltage is not +
And you can't get 300W per channel into 8ohms with a maximum supply voltage of ±40Vdc
Expect 50W into 8ohms from the maximum recommended ±35Vdc shown under POWER :
There are so many mistakes in that page that I would find a different supplier that knows their product.
You need a dual polarity supply for that amplifier and that requires 70Vac to get ±50Vdc
The pic in top right shows a 60V centre tapped transformer (30-0-30Vac). ignore the + they made a mistake. AC voltage is not +
And you can't get 300W per channel into 8ohms with a maximum supply voltage of ±40Vdc
Expect 50W into 8ohms from the maximum recommended ±35Vdc shown under POWER :
There are so many mistakes in that page that I would find a different supplier that knows their product.
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Do NOT wind extra layers to connect with the primary , safety isolation WILL be compromised.
Do wind extra layers and connect in antiphase with the secondary , reducing the output (and VA rating equally)
Or build a stabilised power supply for your LM4702,but unstabilised for the power transistors. You will also loose some headroom and output this way.
Do wind extra layers and connect in antiphase with the secondary , reducing the output (and VA rating equally)
Or build a stabilised power supply for your LM4702,but unstabilised for the power transistors. You will also loose some headroom and output this way.
I hope you have a 230:35-0, 35-0Vac transformer.
You need a dual polarity supply for that amplifier and that requires 70Vac to get ±50Vdc
The pic in top right shows a 60V centre tapped transformer (30-0-30Vac). ignore the + they made a mistake. AC voltage is not +
And you can't get 300W per channel into 8ohms with a maximum supply voltage of ±40Vdc
Expect 50W into 8ohms from the maximum recommended ±35Vdc shown under POWER :
There are so many mistakes in that page that I would find a different supplier that knows their product.
after rectified the 35 0 35vac transformer's output, i am getting +50 0 -50 vdc. this is a 7 ampere transformer, isn't that enough for this amp?
I think my previous message is worth repeating.There are so many mistakes in that page that I would find a different supplier that knows their product.
I think my previous message is worth repeating.
so do you have any other suggestion instated of this one, it would be great if it is a 600w.
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