Peak Power Measurement

[tb303]

Hi,

I'd like to have some kind of visual feedback on how much peak power my speakers are seeing in order to stay within the limits of the system.

Ideally some kind of meter, but a simple LED that flashes up once a set power threshold is crossed would also do the job just fine.

Has anyone done this?

Thanks.

 

[theAnonymous1]

A $7 LED VU meter on eBay would work. It has a trim pot to set the detection level.

LM3915 10LED Audio Level Indicator DIY VU Meter Preamp Power Amplifier Indicate | eBay

 

[tb303]

The LM3915 seems to be the ticket.

I'll have to figure out if the ebay board is set up for peak or avg detection.

Anyhow, building the LM3915 circuit seems very easy to diy.

Thanks for the link.

Edit:
On another note, it's not exactly a power measurement, right?
Is there something available that also takes the current into account, with a shunt resistor or something.

The voltage measurement is probably good enough, though.
I just want to make sure that I don't overload my drivers.

 

[jackinnj]

The LM3915 seems to be the ticket.

I'll have to figure out if the ebay board is set up for peak or avg detection.

LM3915 is discontinued by TI, but the part is generally available. This datasheet will help you figure out the appropriate peak or average rectifier/hold circuits.

http://www.experimentalistsanonymous.com/diy/Datasheets/LM3915.pdf

I had boards burned for the VU meters seen on EBay for $8 or that vicinity. These can be 100 to 300uA full scale.

Instead of using germanium 1N34 type rectifiers, or Schottky's it uses a rail-rail opamp for precision rectification. R6, C1,C2 are used to give VU ballistic characteristics. Switching in C4 gives peak detection. R10 shunts the meter for the proper scale, and R11 limits the current through the meter.