I have a project using a 10V/5V dual output transformer. The secondary can be wired in parallel (5V) or series (10V) and series may be center tapped. The datasheet is here. My project requires regulated 3.3VDC, unregulated 5-6VDC, and unregulated of at least 8VDC. I connected the transformer in series and connected a (full wave) bridge across the outer connections (both coils in series) and connected another bridge to the center and one of the outside connections (across one coil). I connected the "minus" output of each bridge together to form my common ground. The ac input to each bridge was measured to be 13VAC and 6.5VAC respectively under almost no load conditions which is just fine. My problem is I measure 15.4VDC out of the center tapped bridge with a large smoothing cap (470u) and only a ld1117v33 regulator (which is under no load) as a load. The series bridge gives almost 18VDC which is correct. According to (6.5/.7)-1V I should see about 8VDC out of the problem bridge.
Could this be attributed to incorrect connection of the center tap bridge? Does dot convention come into play? Also, as I write this I wonder if oscillations in the regulator could be confusing my cheap meter. I have a large input capacitor and only a small (.1u) output cap on the regulator but I do measure a 3.3V output as it should.
Looking at my PCB and the datasheet I have the center taped bridge connected to pins 8 and (6/7) of the transformer.
Any help would be greatly appreciated.
Thanks,
GTech
Transformer is the 310 model. 5V/10V
Could this be attributed to incorrect connection of the center tap bridge? Does dot convention come into play? Also, as I write this I wonder if oscillations in the regulator could be confusing my cheap meter. I have a large input capacitor and only a small (.1u) output cap on the regulator but I do measure a 3.3V output as it should.
Looking at my PCB and the datasheet I have the center taped bridge connected to pins 8 and (6/7) of the transformer.
Any help would be greatly appreciated.
Thanks,
GTech
Transformer is the 310 model. 5V/10V
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