Correct, join "2"-"3" and measure "1" to "4". If you measure around 260V, you disconnect "2"-"3" and you join "2"-"4" instead (and measure "1" to "3").
Let me hear when you measure around 200Vac.
What we are doing here is the same as if you stack batteries: If you put a 6V battery on top of a 12V battery, you have 18V. If you turn the 6V battery around, the 6V are subtracted from the 12V and you get 6V.
For a transformer, the voltages are not static as for a battery so we do not talk about "polarity" as for a battery but "in phase" or "counter-phase".
Let me hear when you measure around 200Vac.
What we are doing here is the same as if you stack batteries: If you put a 6V battery on top of a 12V battery, you have 18V. If you turn the 6V battery around, the 6V are subtracted from the 12V and you get 6V.
For a transformer, the voltages are not static as for a battery so we do not talk about "polarity" as for a battery but "in phase" or "counter-phase".
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Then, it is 2-4 we want. 222Vac is above what we could expect. The secondary was a 30Vac output?
The high value may drop with loading.
Now, connect the new "output" from terminals "1" and "3" (with 222V) to the primary (230V input) of your 30-0-30 transformer. Then, measure the rectified output voltages (with rectifier, 5600uf buffer capacitors and 330 Ohm loads).
Before it was 44.7V, now?
The high value may drop with loading.
Now, connect the new "output" from terminals "1" and "3" (with 222V) to the primary (230V input) of your 30-0-30 transformer. Then, measure the rectified output voltages (with rectifier, 5600uf buffer capacitors and 330 Ohm loads).
Before it was 44.7V, now?
Hi gimpchop,
32.4V and 32.1V seem much better. A slight concern is that there is little consistency between the values you have measured on the 30-0-30 transformer, the small transformer and now the rectified output.
Could it be, the battery in your multimeter is almost flat?
Anyway, now you have seen how you can make a power supply with two transformers that appears to have a useful output voltage. I cannot see the power rating of the small transformer: When you have your amplifiers ready, let them play at good sound level for an hour and see if any of the transformers become warm. Always use a fuse in the primary of the small transformer and remain careful not to touch the high-voltage wires and terminals.
A two transformer solution is not as good as a single transformer solution because you have more idle losses and your voltage will sag more than if you had only one transformer.
When you become rich, buy a better transformer. But until then, you can use this combination.
Good luck with your LM3886 project.
32.4V and 32.1V seem much better. A slight concern is that there is little consistency between the values you have measured on the 30-0-30 transformer, the small transformer and now the rectified output.
Could it be, the battery in your multimeter is almost flat?
Anyway, now you have seen how you can make a power supply with two transformers that appears to have a useful output voltage. I cannot see the power rating of the small transformer: When you have your amplifiers ready, let them play at good sound level for an hour and see if any of the transformers become warm. Always use a fuse in the primary of the small transformer and remain careful not to touch the high-voltage wires and terminals.
A two transformer solution is not as good as a single transformer solution because you have more idle losses and your voltage will sag more than if you had only one transformer.
When you become rich, buy a better transformer. But until then, you can use this combination.
Good luck with your LM3886 project.
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