Build me a ultra low power 8 led vu meter circuit (buffered)
Budget: $10 – $30 AUD
I need a circuit to show audio level (~0-2V) on 8 LEDs as a bar graph, but using very low current, and not effecting audio signal.
I can build a basic circuit using LM339 comparators, but I'm too inexperienced to make it ultra low power.
The circuit needs to be powered from 48Vdc phantom power, which can only supply about 8ma.
So it will require all the components to draw very little current.
The LEDs do not need to be bright, so the smaller and low more powered the better.
And lastly, the circuit should have no affect on the input signal, so it will require a buffer, presumably in the form of impedance and low power opamp.
It would also require a way for the input range to be adjusted (perhaps by adjusting opamp gain)
So at lowest setting, meter shows 0-500mv range
Highest settings 0-3V range.
I only require Eagle .scm file so I make my own .brd for test PCB with through hole components, and later I can switch to SMD.
I can build a basic circuit using LM339 comparators, but I'm too inexperienced to make it ultra low power.
The circuit needs to be powered from 48Vdc phantom power, which can only supply about 8ma.
So it will require all the components to draw very little current.
The LEDs do not need to be bright, so the smaller and low more powered the better.
And lastly, the circuit should have no affect on the input signal, so it will require a buffer, presumably in the form of impedance and low power opamp.
It would also require a way for the input range to be adjusted (perhaps by adjusting opamp gain)
So at lowest setting, meter shows 0-500mv range
Highest settings 0-3V range.
I only require Eagle .scm file so I make my own .brd for test PCB with through hole components, and later I can switch to SMD.