aleph 5

[harryeng]

Originally posted by intense-tavda
Is this for one channel?

Hi intense-tavda,

No, this is for two mono PSU's as you specified in the first mail.
The four red circles are the two voltage (+ and -) outputs for every channel, the two missing zero's (0) are meant to be on the thick green bar. This represents the central zero of the amp.

When you would use four rectifiers, the drawing changes ofcourse. then you get twice the drawing as show in the first mail in this thread:


inductor/choke/air core/ferrite core. . . same thing?
(I build one myself based on this design)

Greetings, Harry

[intense-tavda]

Thanks Harry!
But I did it the Nelson way and the difference between the + and - rail was very big. Something like 25V. Only I connected the 4 wires together from both trannies wich I connected to the rectifiers. so each trannie has 4 secundairies, wich one should I connect. Is it possible that I destroyed the rectifiers?

[intense-tavda]

I,ve got a red, blye, yellow and grey wire, wich ones ar for the GND? Someone can tellme? Thanks!

[harryeng]

Originally posted by intense-tavda
I,ve got a red, blye, yellow and grey wire, wich ones ar for the GND? Someone can tellme? Thanks!

Hi intense-tavda,

I blew up my rectifiers when I connected my trannie wrong. I connected the wrong pair together, and actually shorted the tranny over the two rectifiers!

Where did you get your tranny? As you are dutch, chances are that you have an Amplimo. The colours match.
Check this: 300 VA Amplimo If this is the same, connect yellow and blue to central zero. Red and grey go to the rectifier.

You can also measure (CAREFULLY) between all these wires. When you select a wrong pair, you get about the same value on the pairs or zero.
When you select the right pairs, you get exactly the same values (25A).

DO NOT SHORTEN WHEN MEASURING

When you have the right pairs, it does not matter which one you connect to the central zero.

Greetings,
Harry

[harryeng]

You cannot connect four wires from two different trannys to the rectifier. The trick is to connect the central connections to the zero instead of the rectifier.

Even if you connect the correct phases, you still only bring one floating voltage over the two capacitors. The plus and minus voltage resulting would then be defined by the internal ohm value of the capacitors. And these are very small.

This is why Nelson uses two voltages, and couples them together over the central zero. This way the plus and minus are equidistance to the central zero point.

When you would use four bridges, you get four floating voltages, that are only connected to ground.

Greetings,
Harry.

[intense-tavda]

Hi there!
I think I got it right, I now got almost 30v + 35- on the rails, so I will wait to see whats going. Thnaks Rchua, Harry and Magura.
I did not have the wires from the trannies right.

[intense-tavda]

Hi there!
I connected the blue and the yellow together, from each trannie apart, but did not connected them to ground, doe I have to do that? Or can I leave it this way? I left the amplifier on for about 2 ours and get now for one channel + 32,6v and - 41,4v, for the other channel - 40,6 and + 33,1, where does te difference come from? I will check it tomorrow.

[harryeng]

Hi intense-tavda

Check mail 15.
When you do not connect the central wires to zero, you create one floating voltage of 75 volts. This voltage is divided over the two capacitors because of resistor values of the capacitors and the connecting bolts.

When you connect the central wires to zero, you create two voltages around one central voltage. When you tie this one to zero, you get what you want.

I tried to make the connections clearer on the schematics.

Disconnect the capacitors, and measure between the outputs of the rectifier and the two connected wires from the trannies. These values should be the same.

Happy Hunting, Harry.

[intense-tavda]

He Harryeng
I did what you and master told me, i put the wires to ground zero, but there is still some difference between left en right and + and -, for left there is -39,7V +36,8V, for right there is -39,2V and + 36,5V, so what is happening here? Should it be exactly 34 for - and 34 for +? Teake.

[harryeng]

Strange,

Something is not right. Maybe the rectifier or the elco are blown? You are measuring without a load i presume?

I would disconnect the elco's and measure directly between the rectifier output and zero. When these still give a difference, measure the rectifier input and zero (=tranny output).

This should give you a clue about where to look. The plus and minus side of all these measurements should give identical values.

Greetings, Harry.