Hi guys, got a quick one for you all.

I'm using a fpv mic on my ET setup, the problem I'm having is that the audio output of the mic is really loud, the system is set to vol1 for external audio but is still too loud, not massively but just by enough, the voice alerts are half as loud & are at the correct volume, I don't want to turn them up, I'd rather reduce the mic vol.

Can I add a resistor to the mic signal wire Into the osd to lower the volume level of the source rather than adding one on OSD's audio out like suggested in the manual.

Mic I'm using is here:http://www.firstpersonview.co.uk/acc...crophone-1-20v

Thanks for any advice.

Hi Flyn,

That certainly won't hurt anything to try it. you might want to use a small 1K pot temporarily, which would let you determine the actual resistor value to use. You may also need more than 1K.

Originally Posted by billpa

Hi Flyn,

That certainly won't hurt anything to try it. you might want to use a small 1K pot temporarily, which would let you determine the actual resistor value to use. You may also need more than 1K.

Hi Billpa,

Thanks for the reply mate, due to the lack of a pot,on the signal wire I soldered inline a low value 3k resistor with no change so I went higher, then a few resistors to make 38K!!

It didnt seem to have any effect, I went to crazy values, 200k & it did nothing. I don't understand why this is....

Thanks

Originally Posted by flyn

Hi Billpa,

Thanks for the reply mate, due to the lack of a pot,on the signal wire I soldered inline a low value 3k resistor with no change so I went higher, then a few resistors to make 38K!!

It didnt seem to have any effect, I went to crazy values, 200k & it did nothing. I don't understand why this is....

Thanks

Maybe because of a very high input impedance. I would try with a logarithm pot, with both extremes at gnd and input, and the middle pin to output. If you want to use just resistors, make a voltage divider with a 10:1 division..

Originally Posted by jcabetas

Maybe because of a very high input impedance. I would try with a logarithm pot, with both extremes at gnd and input, and the middle pin to output. If you want to use just resistors, make a voltage divider with a 10:1 division..

Thanks for the reply mate, appreciate it. It may seem like I know what I'm talking about but in truth I'm a bit of a noob with the ins & outs electronic components - they say a little knowledge is dangerous lol.

You might have to explain a few things, log pots & voltage dividers, thanks man.

Originally Posted by flyn

You might have to explain a few things, log pots & voltage dividers, thanks man.

When you increase the power of an amplifier 10 times, you perceive it as a double loud sound, making the ear response not linear. To make things easier for sound aplications, there are pots in wich the resistance is logarithmic distributed. You can live with an ordinary pot, but adjustments are more dificult to do.

The ouput of any amplifier or mic is equivalent to a voltage in series with the output impedance. To get a lower voltage level you can put two other resistances in series, connected from the voltage source to ground. The voltage trough the resistance R2 connected to ground is:
Vdivider=Vinput*R2/(Routimpedance+R1+R2)

It is usual to use resistances such that the sum are more or less equal to the output impedance. Then you have to choose R1 and R2 to get the factor you are looking for... Or just use a pot.

Sorry, you ask for an explanation

Haha, I did ask for an explanation didn't I, careful what you wish for I guess!!

Thanks for the reply, electronics, wow different world or what!!

If I were going to use a log pot to lower the volume, bearing in mind that 200k ohms didn't do a whole lot, maybe a slight change but what would you suggest?

Would a voltage change help lower the mic volume? As the mic I'm using is stated to work from 1-20v so I guess it has a regulator onboard, it does have a load of circuitry on it.

Flyn, I don't know how you connected the pot. What I would try is connecting it like this:

Originally Posted by jcabetas

Flyn, I don't know how you connected the pot. What I would try is connecting it like this:

Cool mate, not got a pot on at the min, had those resistors inline on the signal wire.

The mic has its own small board packed with components, with x3 wires, black red & signal.

Sorry to be a pain, any idea on a ball-park value on a log pot?

Thanks man

Originally Posted by flyn

Cool mate, not got a pot on at the min, had those resistors inline on the signal wire.

The mic has its own small board packed with components, with x3 wires, black red & signal.

Sorry to be a pain, any idea on a ball-park value on a log pot?

Thanks man

Try your resistors as above, across the mike instead of in series. Might not need the pot.
That would be from signal to ground.

Cheers mate, will give it a try. Thanks.