average volts to dc

I need a circuit to take in a PWM signal (Vin) and output the average voltage (Vo = D*Vin). Any ideas?

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On 9/15/07 3:53 PM, in article 46ec6230$0$7087$ snipped-for-privacy@news.optusnet.com.au, "Warren Thai"

Use a d'Arsonval meter. No electronics or power supply is necessary.
Bill -- Fermez le Bush--less than 18 months to go.
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On Sun, 16 Sep 2007 08:53:00 +1000, "Warren Thai"

Use a low pass filter and put the PWM frequency far over the filter's cut-off frequency. (Remove the two Roentgen-ray characters to reply.)
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On Sun, 16 Sep 2007 08:53:00 +1000, "Warren Thai"

The low pass filter (e.g. resistor-capacitor) is the obvious first answer, but how about also requiring a fast response time?
Now I'm thinking maybe a switched integrator. Any other ideas?
dave y.
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Warren Thai wrote:

As others have suggested, there are analogue methods of averaging, using mechanical, electrical or thermal techniques.
However, as this is presumably a fixed amplitude signal, simple digital techniques are also available using the timing of the edges of the signal.
I won't mention the device-type of choice, as (1) everyone knows what it is and (2) some go spare just at the mention of the acronym.
It will have many advantages - including that of a much faster response time than any analogue system - as it will produce a valid output almost immediately after the first pulse has been registered. However, it will, of course, produce a quantised output signal which may need analogue techniques to reduce the transient component.. ;)
--
Sue


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