I'm toying around with a Nakamichi tape deck that has separate knobs for R/L recording levels and I'd like to make a test jig for matching the levels (the meters are not accurate enough).
The most basic idea could be a LED that is fed by the voltage difference between both channels, when it is dimmest it is matched (although resolution might not be great)
Or a row of LEDs that is centered when balanced and lit on either side depending on whether the voltage difference is positive or negative.
Also open to a display/voltmeter module but seems like it would be more complex.
I don't know where to start on how to design such a schematic, any help or suggestions would be appreciated.
The most basic idea could be a LED that is fed by the voltage difference between both channels, when it is dimmest it is matched (although resolution might not be great)
Or a row of LEDs that is centered when balanced and lit on either side depending on whether the voltage difference is positive or negative.
Also open to a display/voltmeter module but seems like it would be more complex.
I don't know where to start on how to design such a schematic, any help or suggestions would be appreciated.
Yea that seems decent. Not sure about the resolution though as it seems like 2 LED's cover 3dB and I want something that I can adjust much better than that.
My idea is for something fairly small that runs on batteries that I could quickly plug into the headphone jack and remove.
My idea is for something fairly small that runs on batteries that I could quickly plug into the headphone jack and remove.
Difference op amp circuit, feeding an active FW rectifier, then a filter with a controlled ~1s time constant decay.
LED with variable resistor on the output for sensitivity. Could get by with a half wave rectifier if the input is a sine.
Will run on single supply with a 9V battery, or two 9V batteries for a balanced supply.
Needs a power switch to save the batteries.
https://www.electronics-tutorials.ws/opamp/opamp_5.html
https://www.analog.com/media/en/training-seminars/tutorials/MT-211.pdf
LED with variable resistor on the output for sensitivity. Could get by with a half wave rectifier if the input is a sine.
Will run on single supply with a 9V battery, or two 9V batteries for a balanced supply.
Needs a power switch to save the batteries.
https://www.electronics-tutorials.ws/opamp/opamp_5.html
https://www.analog.com/media/en/training-seminars/tutorials/MT-211.pdf
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So you can play with this (with lower number of steps):
https://www.proaudiodesignforum.com/forum/php/viewtopic.php?t=1162
Martin
Right, I used a DVM across the outputs in lieu of the device.
Possibly the simplest solution is an analog panel voltmeter (mV scale) connected directly to a headphone jack?
Possibly the simplest solution is an analog panel voltmeter (mV scale) connected directly to a headphone jack?
You would need a "center tune" meter movement, where the zero is at the center of the scale, not at the left end.
You need both positive and negative, like this one: https://www.ebay.com/itm/311954599802
But probably will still need a variable sensitivity pot in series, to get them exactly equal.
You need both positive and negative, like this one: https://www.ebay.com/itm/311954599802
But probably will still need a variable sensitivity pot in series, to get them exactly equal.
Thanks for brainstorming with me on this. It is overkill but I'd like to go with a solution that minimizes error, so I'll pass on LED or analog meter.
Back to the approach from post #4, with something like this on the output?
https://www.digikey.com/en/products/detail/lascar-electronics/V-125/10259135
Is the filter at the output of the rectifier still necessary in that case?
Back to the approach from post #4, with something like this on the output?
https://www.digikey.com/en/products/detail/lascar-electronics/V-125/10259135
Is the filter at the output of the rectifier still necessary in that case?