Confused!

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Hello everyone,

I am a bit confused with the power supply I have, I know there are some factors to consider but not sure what they are.

I have X'former which I made with an output of 2 x (40.5-0-40.5 VAC).

The 40.5 VAC, when rectified (40.5 x1.414) should have 57 Vdc, but I am only getting 53-54 Vdc.

What could be the issue?


Thanks
 
Hello everyone,

I am a bit confused with the power supply I have, I know there are some factors to consider but not sure what they are.

I have X'former which I made with an output of 2 x (40.5-0-40.5 VAC).

The 40.5 VAC, when rectified (40.5 x1.414) should have 57 Vdc, but I am only getting 53-54 Vdc.

What could be the issue?


Thanks

Don't forget to factor in the voltage drop across the diodes.
 
Is it rectified and smoothed, or just rectified? If the latter then you are seeing more voltage than you should. If the former then how much does your incoming mains voltage vary from day to day?


yes it is smoothed, using a 10000uF/63V Capacitor.
well, at daytime it goes to 215V and went to 225V at night, but regardless, I used to measure when the output of the X'former is 40.5Vac
 
In Philippines as I read you have 220V.
Maybe the transformer was designed to be use with 230V and using with 220V will exactly make 54V instead of 57V. Or simply the network is not that stable and lower than it should be.


Well I have rewound the output to get a 40.5Vac output, when rectified we should get a close value to 57Vdc, less the vdrop on the bridge rectifier we could get 55Vdc.:confused:
 
YOU-DO-NOT-HAVE-A-PROBLEM :D

You are within 3.5% of expected voltage. :)

Wall voltage alone can have up to 10% error; in fact you measured variations between 215 and 225V so there you already have 4.5% variation.

That said, please read the user manual accompanying your multimeter.

Somewhere it will typically state that "DC precision is 1.5 to 3%" and "AC precision is 5%" or something very similar.

So in a nutshell you are real close and there will be small measurement errors (not yours but multimeter calibration) .

Don't overthink it, we are all doing this for fun :D
 
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