jit_singh_tara
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I though you wereI will be generating 5V dc using 7805 .
generating 2 supplies :
1.5V regulated power supply .
2.8V unregulated power supply.
But i am using the centre tapped transformer followed by the full wave rectifier ...
If i use 0-7 transformer of the same rating followed by a bridge will it solve my purpose . i.e will it reduce the heating of the transformer......
I think by doing this i will be utilizing the full secondary winding for drawing the current though the drop will be more bcoz of 2 diodes in either direction.....
Sorry, my fault. I said half-wave but meaned full-wave dual-diode.But i am using the centre tapped transformer followed by the full wave rectifier ...
What does it means it is heating too much? Allowed temperature rise for small transformer can be 55°C.
I am generating 5V for running mcu and display and 8v for relay . Overall i am drawing 140mA . My transformer is rated 150mA. It is heating too much .
I want to know that if a centre tapped transformer is rated 150mA , and i am using it in the config as shown in the fig . Then am i drawing 140mA from the complete secondary winding or i am using only the half of the winding.....?
Because my transformer is heating too much....
Then what is the theory behind that, Transformer heating on no load and reducing heat in when loading sounds like a CT Isnt it?I have a cheap 9V/100mA AC/DC adapter (guess where it was made) that has an output higher than 18V with no load and with no load it gets HOT!
With a 100mA load its output is 9V and it does not get much hotter.
I am totally agree with this.You can't draw the full rated current from a transformer with a rectifier-capacitor load. Due to the high peak current drawn from the transformer by a rectifier-capacitor supply, the RMS current in the transformer is much higher than the DC output of the rectifier-capacitor.
In fact, it's more the distortion than the reactive power factor that enforces a higher transformer VA. Center tapped transformer circuits are at an additional factor 0.7 disadvantage due to non-continuous (alternating) current flow.In other words rectifier with smoothing capacitor represent capacitive load to transformer. Transformer power rating expressed in VA can be exceeded even when real power is only half of that. Then transformer get hot because of large out of phase currents.
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