Building a 12 VAC to 5 VDC bridge...

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 27, 2009

• #1

I'm looking for a schematic for a small bridge rectifier to convert 12 VAC to 4.5-5 VDC @ approx. 10ma.

Has anyone got anything like this they'd like to share or can anyone tell me where I might find a drawing for this?

Thanks!

 

Last edited: Apr 27, 2009

Wendy

Joined Mar 24, 2008

23,797

Apr 27, 2009

• #2

Not sure what you're looking for exactly, but this is a fairly basic power supply circuit. With such a low current a linear regulator is a pretty good choice, though you will probably want to heat sink the regulator chip.

Bridges can be either bought as components, or built using discrete diodes.

 

Last edited: Apr 27, 2009

C

carcia

Joined May 12, 2006

2

Apr 27, 2009

• #3

It should be the short answer, congratulations..

 

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 28, 2009

• #4

Thanks for your help!

 

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 28, 2009

• #5

And am I correct to assume the diodes would be 1N4001?

Thanks again for your help!

 

gerty

Joined Aug 30, 2007

1,305

Apr 28, 2009

• #6

1n4001 would work just fine...

 

gerty

Joined Aug 30, 2007

1,305

Apr 28, 2009

• #7

Also , in your case the regulator would be marked "7805" for a fixed 5 volt regulator.

 

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 29, 2009

• #8

If I wanted to adapt this configuration to a different output voltage, how would I calculate the change in components? If I wanted to change the output to 3v dc, would simply changing the voltage regulator to 7803 do the trick?

I don't mean to ask stupid questions... I just don't have the electronics background to complete a project.

Thanks!

 

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 29, 2009

• #9

One more question... What would be the maximum output of this circuit at 5v?

Thanks.

 

S

Thread Starter

sd_sparky

Joined Oct 20, 2008

6

Apr 29, 2009

• #10

I found this second drawing on another site. It's very similar to the circuit posted by Bill Marsden. Bill's uses a 100μF capacitor and the other uses a 50μF and a 0.1μF in parallel.

Is there any advantage or limitation to either design? Do both do the job equally well?

Bill's Circuit

New Drawing

Also, This drawing shows the 50μF at 35v. I keep finding 25v and 50v capacitors, but no 35v. Would a 50μF 50v work?

Thank-you!