30-Jan-2018, 09:03 AM (This post was last modified: 30-Jan-2018, 09:17 AM by xcalibur.)
How did you connect it? Like this?
Using it is simple: connect GND to ground, VCC to 2.4-5VDC. For the best performance, use the "quietest" supply available (on an Arduino, this would be the 3.3V supply). The audio waveform will come out of the OUT pin. The output will have a DC bias of VCC/2 so when its perfectly quiet, the voltage will be a steady VCC/2 volts (it is DC coupled). If the audio equipment you're using requires AC coupled audio, place a 100uF capacitor between the output pin and the input of your device. If you're connecting to an audio amplifier that has differential inputs or includes decoupling capacitors, the 100uF cap is not required.
I did not use this device to connect the audio MIC. Simply, I put the 2 wires (ground & audio of the VTX ) to the MIC's 2 pins, that's all. Here is the MIC that I have used, no additional device attached.
THe problem is when I attached the MIC's 2 pins with the VTX's ground & audio, it does not sound,,,guessing the MIC's voltage issue or wht? Check the attached pics pls.
An electret microphone needs some power if it is going to output anything. Inside the capsule will be a JFET which buffers the sensor itself with a very high impedance.
The usual way to connect an electret microphone is like this:
The audio input impedance of your VTX is listed as being 10K Ohms, so the value of the resistor connected to power should also be 10K. The AC coupling capacitor on the output should be about 1uF. You'll need 5V to power the microphone and this 5V needs to be completely clean and with no ripple or noise. Any noise in the input voltage will be imposed on the signal from the microphone.
The only problem is that all you will get is about 4 millivolts of audio signal and your VTX is expecting a 1V audio signal! The only way around this is to add an amplifier to the output to bring the voltage into the correct range.
Suddenly, we've gone from one little microphone to needing quite a few components and a low noise voltage regulator to deliver clean power!
I'd suggest that you need to look for a more integrated solution like the Sparkfun electret microphone board which contains an amplifier circuit to bring the microphone's output up to the levels that you need. See: https://www.sparkfun.com/products/12758 You'll still need to supply clean power to it though.
01-Feb-2018, 07:15 PM (This post was last modified: 01-Feb-2018, 07:31 PM by lotaloi.)
(31-Jan-2018, 12:29 PM)unseen Wrote: An electret microphone needs some power if it is going to output anything. Inside the capsule will be a JFET which buffers the sensor itself with a very high impedance.
The usual way to connect an electret microphone is like this:
The audio input impedance of your VTX is listed as being 10K Ohms, so the value of the resistor connected to power should also be 10K. The AC coupling capacitor on the output should be about 1uF. You'll need 5V to power the microphone and this 5V needs to be completely clean and with no ripple or noise. Any noise in the input voltage will be imposed on the signal from the microphone.
The only problem is that all you will get is about 4 millivolts of audio signal and your VTX is expecting a 1V audio signal! The only way around this is to add an amplifier to the output to bring the voltage into the correct range.
Suddenly, we've gone from one little microphone to needing quite a few components and a low noise voltage regulator to deliver clean power!
I'd suggest that you need to look for a more integrated solution like the Sparkfun electret microphone board which contains an amplifier circuit to bring the microphone's output up to the levels that you need. See: https://www.sparkfun.com/products/12758 You'll still need to supply clean power to it though.
1st of all, thanks for yr kind reply. Problem is that I am not from an electronics background who understands those schematic diagram that much except just a little bit. I am an RC hobbyist only.
I did some research online found the MIC needs to be feed some power like 3-5 V or whatever. I thought the Eachine VTX has 2 wires extra for audio so, I would jst hook up with MICs 2 pins & my job done. Then question arises, why that 2 wires from Eachine VTX already has no power provided, the customer like me has to arrange that!!!!!!! The customer should only joint that 2 wires to MIC & it should pick up sound.
Could u pls answer this question? Which MIC from Banggood I can directly hook up to my 2 wires coming out of the VTX????????? I am researching more & will do sme trial & error basis tests. Seems it is easy actually let me see... Thanks.
I already gave you the answer to what will work in the link to Sparkfun.
The wires for the audio input on your VTX are a ground wire and a signal wire. You cannot drive an electret microphone from these wires. The VTX specifications are clear on this: it expects a 1V peak-to-peak audio signal.
The input to the VTX consists of two things: a 1V video signal and a 1V audio signal, just like you would get from a compatible video camera that includes a microphone. The way this interface works comes from the days of analogue video systems like video recorders and video cameras - a composite video signal and a separate audio signal.
Just because something is a microphone does not mean that they all output a 1V signal. As you don't have electronics knowledge, you would be better served by buying an FPV camera which has a microphone included as part of the camera. If the camera is designed for FPV use, you can be sure that it will have the required circuity to produce a compatible audio signal. Some video transmitters have a microphone included instead of expecting the camera to include one.
Write off your purchase of the electret microphone to experience and get a camera or VTX that includes a microphone.
02-Feb-2018, 01:59 AM (This post was last modified: 02-Feb-2018, 02:00 AM by lotaloi.)
(01-Feb-2018, 08:01 PM)unseen Wrote: I already gave you the answer to what will work in the link to Sparkfun.
The wires for the audio input on your VTX are a ground wire and a signal wire. You cannot drive an electret microphone from these wires. The VTX specifications are clear on this: it expects a 1V peak-to-peak audio signal.
The input to the VTX consists of two things: a 1V video signal and a 1V audio signal, just like you would get from a compatible video camera that includes a microphone. The way this interface works comes…………
Write off your purchase of the electret microphone to experience and get a camera or VTX that includes a microphone.
I connect it through a step down converter 12 to 5 volt. Camera produce nice sound tht comes to the FPV monitor.
However, I also hv to learn how to hook up the MIC to the VTX & I shld knw it. Let me get the capacitors & registor I will do it, not seems difficult :-) Thanks.
(01-Feb-2018, 08:01 PM)unseen Wrote: I already gave you the answer to what will work in the link to Sparkfun.
The wires for the audio input on your VTX are a ground wire and a signal wire. You cannot drive an electret microphone from these wires. The VTX specifications are clear on this: it expects a 1V peak-to-peak audio signal.
The input to the VTX consists of two things: a 1V video signal and a 1V audio signal, just like you would get from a compatible video camera that includes a microphone. The way this interface works comes from the days of analogue video systems like video recorders and video cameras - a composite video signal and a separate audio signal.
Just because something is a microphone does not mean that they all output a 1V signal. As you don't have electronics knowledge, you would be better served by buying an FPV camera which has a microphone included as part of the camera. If the camera is designed for FPV use, you can be sure that it will have the required circuity to produce a compatible audio signal. Some video transmitters have a microphone included instead of expecting the camera to include one.
Write off your purchase of the electret microphone to experience and get a camera or VTX that includes a microphone.
Yes, I made the connection properly & the MIC produce some sound, bt it is really low doesn't seem it would pick up the prop sound that much. Amplifier is needed. That's why the MIC comes with a small circuit board having a small amplifier I believe. That amplifier MIC is on now on the way from Banggood. Excellent that I have learned a "connection diagram" of any MIC. Why capacitor & why power is fed for all I know now. Thank u folks.
(03-Feb-2018, 08:00 AM)lotaloi Wrote: Yes, I made the connection properly & the MIC produce some sound, bt it is really low doesn't seem it would pick up the prop sound that much. Amplifier is needed. That's why the MIC comes with a small circuit board having a small amplifier I believe. That amplifier MIC is on now on the way from Banggood. Excellent that I have learned a "connection diagram" of any MIC. Why capacitor & why power is fed for all I know now. Thank u folks.
That's good news!
As I suspected, with no extra amplification, the low signal level from the microphone is not enough. The amplified board looks quite small, so it should be easy to fit and you will be able to get a full 1V signal from it.
Note that you will need a capacitor on the board's output to AC couple the audio signal, as discussed on the product page. I don't know if you have an oscilloscope, or access to one, but it would be useful to help you set the gain on the amplifier so that you don't exceed 1V for really loud sounds.
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