Not sure if my title is correct. I have a LED vu meter that connects to speaker terminal of my receiver. I would like to convert it to a wireless device by adding a microphone. Does anybody know of a circuit that will convert microphone source to a signal that can be connected directly to speaker?
My VU meter is based on LM3915 chip.
Thanks.
My VU meter is based on LM3915 chip.
Thanks.
I still don't know what you want. You cannot answer an either/or question with Yes/No.
G²
OK. Let me start again. This is the circuit that I am going to build:
10 LED VU meter
It connects to the speaker output on the amplifier. Now, I want to make it wireless so I want to add a microphone. Now, what I need is a circuit between the microphone and the above VU meter. I assume that the microphone signal is too weak so it would have to be amplified. Probably by LM386 chip?
Thanks.
10 LED VU meter
It connects to the speaker output on the amplifier. Now, I want to make it wireless so I want to add a microphone. Now, what I need is a circuit between the microphone and the above VU meter. I assume that the microphone signal is too weak so it would have to be amplified. Probably by LM386 chip?
Thanks.
I thought that was what you had in mind. You will need a preamp and likely not an LM386. Rod Elliot's site is a good place to start.
ESP Projects Pages - DIY Audio and Electronics - Audio test equipment
An electret mike requires power to run whereas dynamics do not. Often the mic manufacturer offers simple examples to use their product. The gain of the preamp will likely end up between 50 and several hundred but this depends heavily on what mic and how loud you consider '0'.
The LM3915 requires up to 10 Volts to drive to 0 while mic output tends to be in millivolts. 1 mV boosted to 10V would be a gain of 10,000 though as I said, I expect your gain in the 200 +/- 2 times. Do not attempt to get high gains in a single stage. For 10,000 it could be two cascaded gain of 100 amps
National, Analog Devices, THAT corp, TI (Burr Brown) and others offer mic preamps and examples of how to use the chips in specific applications.
BTW when things are called 'wireless' it's assumed to be RF (radio, wifi etc) and not acoustically coupled as you have in mind.
G²
So you want to make a sound level meter. Also called an SPL meter, or even decibel meter.
Are you interested in this as a project? Or do you just want to be able to measure sound levels? perfectly good and reasonably accurate sound level meters are on the market at reasonable price. You can check SPLs in a flash.
That last post project looks like what you want though.
Are you interested in this as a project? Or do you just want to be able to measure sound levels? perfectly good and reasonably accurate sound level meters are on the market at reasonable price. You can check SPLs in a flash.
That last post project looks like what you want though.
You might want to consider powering it from a DC adapter - a 9V battery won't last long driving those LEDS. Setting the driver to 'dot' mode as opposed to 'bar' mode would keep the current drain lower.
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