Full Bridge Rectify an audio signal?

I'm working on a project that turns on LED's with low frequencies.

I'm switching a FET with the positive alternation. However, this is only giving me 50% duty cycle. I was thinking of putting a full bridge rectifier before the FET to produce a near %100 duty cycle.

Is this possible? If so, where am I connecting the inputs of the rectifier?


Here is a picture of a rectifier to reference diode junctions.

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Here is a link to op amp rectifiers. That is probably the way to go.

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A full-wave bridge rectifier requires an isolated source (such as the transformer shown) which I assume you do not have.

One way to full-wave rectify an audio signal is to use a precision rectifier (see figures 4, 5, and 6). Those circuits also have the advantage of essentially canceling the forward drop of the diodes.

Edit: ronv, you beat me my a few minutes.

Awesome, thanks. The hollow triangle on the bottom of those circuits that aren't connected to anything are ground, correct?

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crutschow said:

A full-wave bridge rectifier requires an isolated source (such as the transformer shown)
.

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I don't understand this statement - could you elaborate ?

crutschow]A full-wave bridge rectifier requires an isolated source (such as the transformer shown) [QUOTE=Ross Craney said:

I don't understand this statement - could you elaborate ?

Click to expand...

[/quote]

It has to be isolated in the sense that one side of the source cannot be grounded, as would the output of a previous audio stage. It has to be isolated from ground, as shown in the diagram above.