Rectifying for Comparator Op Amps/PIC

[chr0n]

If I want to recitify 120VAC to VDC for comparator op amps and send out a signal to a pic to turn on a DC Relay.

How would I go about doing this with a bridge rectifier (what size or types of components) and what would the calculation conversion be to calculate how much VDC it will be rectified to.

Thanks.

 

[sengar_vijay]

use a appropriate step down transformer to step down the ac voltage

then use the rectifier with the regulator 78xx series to get the required dc voltage

 

[Miguel Gaspar]

You can consult this book

HB206-D from the web site of www.onsemi.com

 

[nguyennam]

You want to make a power supply for comparator/opamp?, and send a signal to PIC .... ?

You do not mention how much is supply voltage you need for comp.+opamp, and PIC?
Suppose you will use +5V for supplying comp, opamp, PIC, it means that you will need the signal of +5V for PIC either.

So you need a stepdown transformer of 220VAC-7.5 (or 9)VAC/6VA, 4 diodes 1N4001 for rectifying, a cap of 1000uF/16V for filtering, and a L7805 IC for regulating of 5V. Using the example in L7805 datasheet, you will know how to connect parts together.

nguyennam