[SOLVED] From AC to DC and then limit to it to certain level

[moonnightingale]

Hi, i discussed in detail how to limit AC
Now i want that my peak to peak voltage is 100 Volts
I want to rectify it and make DC and then want to limit it to 0 to 5 V DC.

Kindly help me to make it in proteus as i did not find any recitfier in proteus.
I am having Proteus 7.6

 

[chris109]

Use a transformer to get 10VAC then bridge rectify, add a big cap, then use a 5V reg.
View attachment transformer.bmp

The attachment was created using proteus.

Regards
Chris

 

[FvM]

Hi, i discussed in detail how to limit AC

The primary topic of your previous thread hasn't been "limiting AC", I think. You should clearer tell about the intended application, otherwise you are asking for misunderstandings once more.

 

[moonnightingale]

Use a transformer to get 10VAC then bridge rectify, add a big cap, then use a 5V reg.
View attachment 61563

The attachment was created using proteus.

Regards
Chris

Thanks a lot Chris, i made it in Proteus and it worked
Can u kindly tell me how did u select value of coupling factor of 0.1
Is there any standard method to select it

Secondly when i used a graph before and after Transformer, it showed that after stepping down, the negative part of wave has considerably reduced.
Is'nt should be sine wave with less amplitude but + and minus peak be equal

The graph is attached

 

[chris109]

To measure the AC move the earth to the other side of the bridge rectifier (you can join one terminal of both windings together as shown attached). the wave will still look bad because of the inherent inductance and resistance of the windings, the greater the load the greater the distortion.

The coupling factor factor just simply gives the transformer ratio i.e. 10:1 so 100V input (200V pk to pk) = 10V output (20V pk to pk).

The DC volts will be half the pk to pk volts minus the diode volt drops, the transformer output voltage will reduce slightly with load.

Im no expert on transformers so if anyone reading this would like to chip... The DC output with just one cap is very crude to say the least and complex filters can be built to "smooth" the DC voltage, however lumpy DC is fine for some applications like motor control or electro/mechanical switching, but if you intend on powering sensitive components then just add a reg to the output, for small loads (up to 2A) a linear reg will be fine.

with a 100VAC input this transformer will give around 6.2VAC output at about 0.7A:
MULTICOMP|MCFM70/09|TRANSFORMER, MINI, 7VA, 2 X 9V | Farnell United Kingdom

Add a bridge rectifier, cap and 5V reg and your ready to go.

Dont forget to fuse the DC and AC side.