One transformer, two chips

[phatcenter77]

I just recently purchased the lm4780 kit from Audiosector and am curious about how to use one transformer to power both chips. I plan to use THIS transformer to feed both chips. Each chip will be paralleled.

How should I go about using a single transformer to power both chips? I searched for nearly an hour on this subject but haven't found a good answer...

 

[halo0925]

1 trans 2 chips

Simply wire both rectifier boards to your transformer, make sure you connect the same color wire to the same connection points on the rectifier boards, as so the AC phase angles remain the same if not you will have hummmmmmm.

 

[sivan_and]

The power supply VCC and VEE (+ve and -ve) of each chip can be paralleled with the respective supply pins of other chip, and can be connected to a DC dual power supply..

As far as ur requirement is concerned the transformer o/p volts and VA is adquate for your requiremnt...U should rectify the dual a/c (25--0--25) with a diode bridge and filter with a pair of Electrolytic capacitors..and fed to the Chips via a pair of fuses..

 

[Sangram]

Re: 1 trans 2 chips

...make sure you connect the same color wire to the same connection points on the rectifier boards, ....

Or the thing will simply not work, as I found out - the transformer is shorted out.

 

[phatcenter77]

So I can just use something like this

An externally hosted image should be here but it was not working when we last tested it.

to connect the transformer to the rectifier boards?

 

[Nordic]

100%

---------- +
|
|
---------- G

---------- G
|
|
---------- -

 

[Speedskater]

sangram wrote:

Or the thing will simply not work, as I found out - the transformer is shorted out.

How did you determine that the transformer is shorted?
Measuring a power transformer with an ohm-meter often shows a very low value!

 

[Sangram]

The AC voltage at the secondary terminals was zero (or very close to it) when switched on.

 

[Nordic]

sometimes the leads on the secondary are in the order A1 B1 A2 B2

 

[Sangram]

No no, this was not a toroidal which I had to experiment to find which leads were which. It was a custom-wound EI with terminal blocks for output, and it worked when not connected, or connected to only one of the rectifiers.

Peter's boards are arranged back-to-back. AC1 and AC2 of opposite boards are next to each other. If you connect thme to each other, it creates a short circuit for AC as each diode conducts to the ground leads for half a cycle.

Connecting AC1 and AC2 of each amp to their corresponding entires on the other side fixed it, so I knew it was the connection and nothing but that.