What is the simplest way to control a single LED to indicate the presence of a signal coming into an amplifier? Essentially a VU meter but only using a single LED. This is quite common on the front of amplifiers used in pro audio & I want to replicate something similar for some of my DIY builds (or at least experiment with it).
Can I just use a LM386, connect the signal to pin 3 & the LED +ve leg to pin 5? I'm not expecting the result to be accurate in any way, just to vaguely increase the LED's brightness as the level of the signal increases.
Can I just use a LM386, connect the signal to pin 3 & the LED +ve leg to pin 5? I'm not expecting the result to be accurate in any way, just to vaguely increase the LED's brightness as the level of the signal increases.
Well... increasing the current through the LED doesn't really increase its brightness once it is bright enough. There's a photo here:
LED center How is LED brightness related to current?
So what signal/clipping indicators usually do is have the green orange and red LEDs turn on (or get bright enough) at different input signal voltages.
LED center How is LED brightness related to current?
So what signal/clipping indicators usually do is have the green orange and red LEDs turn on (or get bright enough) at different input signal voltages.
I was thinking about something like the 'signal present' LEDs on the front of a JBL MPX 1200 (a single green LED per channel) which alter their brightness visibly in response to different levels of input - I presume then it must be something more complex than just an LED & an op-amp if the difference in brightness if you just change the current is so little as in your link?
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