2 transformers 15 v 6a to 15-0-15 v at 6a - Page 1
Forum section: electronics / beginners

author: rahulrahullll
author_rank: Contributor
timestamp: December 14, 2017, 03:45:36 pm
content: i have 2 transformers—–same type—–15 v 6a —each———made by same manufacturer-- i join the 0 v of each to make dual rail supply of 15-0-15 v 6a --ac--for amplifier--The turns on a pair of paralleled secondary must be IDENTICAL----i guess they are same as made by same manufacturer-------cheap transformer rated at 16-0-16 v 6a w.r.t to 2 rails so each rail gets 3a ?my main intention of making this--------because 2 16 v transformer cheaper than 16-016 v transf---and i will get 6a on each rail ?now what do you think can it be done without any issues ?thank you

author: Connoiseur
author_rank: Regular Contributor
timestamp: December 14, 2017, 04:13:48 pm
content: Quote from: rahulrahullll on December 14, 2017, 03:45:36 pmNo you cannot get 15-0-15 that way. You should connect 0 of one transformer to 15 of the other. However this will work if and only if the winding polarities have been marked in a consistent manner by the manufacturer.A better approach is connect the primaries in parallel first (and don't change it later) then connect 0V of first transformer secondary to 15V of other; measure the voltage across the other two ends. It should read about 30V, otherwise swap the secondary of any one transformer.Quote from: rahulrahullll on December 14, 2017, 03:45:36 pmThey must be same, however given the fact that a majority of cheap transformers in India are hand wound in small workshop by unskilled labour, I doubt it would be. Why are you asking about paralleling? Your requirement does not need a parallel connection.Quote from: rahulrahullll on December 14, 2017, 03:45:36 pmNo each will get 6A. Current is not halved in a center tap transformer it's voltage alone.Quote from: rahulrahullll on December 14, 2017, 03:45:36 pmCould you please rephrase the above sentence and provide a circuit diagram maybe. That will help us better understand your problem and offer appropriate suggestions.

author: Audioguru
author_rank: Super Contributor
timestamp: December 14, 2017, 05:11:06 pm
content: It is silly to use two transformers to replace a center-tapped transformer.15VAC when rectified and filtered produces about 19VDC when loaded. It might be 24VDC when lightly loaded. Will your amplifier survive plus and minus 24V?

author: rahulrahullll
author_rank: Contributor
timestamp: December 14, 2017, 07:30:41 pm
content: thanks everybody------------Connoiseur---------You should connect 0 of one transformer to 15 of the other. -----this means connection series connection--------then will i get 15-0-15 v ac @6a as output ?

author: Benta
author_rank: Super Contributor
timestamp: December 14, 2017, 09:43:31 pm
content: There's no problem at all in doing this.You need to phase the transformers correctly, but with an AC voltmeter it's easy.Connect the primaries in parallel.Connect two wires from the different secondaries together (= series).Measure the voltage across the non-connected secondary wires. If it's around 30 V AC, you have your 15-0-15 V combo. If it's around 0, swap one of the secondary wires and measure again.Yes, you'll have 15-0-15 V @ 6 A at the end.