external Microphone

Questions, Answers and Cool Stuff
41

Hi Doug -

Don’t give up just yet - I have that microphone working reasonably well in a noisy old 1987 muscle car and I can communicate with MOVI up to about 40MPH when the wind noise just takes over.

I cannot find the link from the old forum posts that contained the values for the attenuator components, but I THINK this is what was recommended:

https://geoffthegreygeek.com/understanding-decibels-part-2/

Scroll to the 40dB attenuator piece.

If that’s still not good enough - Try building the Voice Bandwidth filter I linked above. It helped me out a bunch with the random noises being picked up.

For me, Threshold of 3 is all that would work. 2 and MOVI doesn’t hardly hear anything. 4 and up, it just keeps listening to random noise constantly.

Good luck,
Dylan.

42

Hi Dylan,

Finally found this thread, Gerald pointed me at it, but I suppose I screwed up the URL before.

Sounds like we have very similar problems. My project is voice operated controls (TV, STB, AC, pager …) for a quadriplegic person. Gives them some freedom and caregivers (me :-)) a break. Could be a very nice option for others in similar situations.

Many of the same problems with an external mic. My problem doesn’t come from automotive issues, but rather room noise. People speaking, audio from TV / music.

I’ve accumulated a box of microphones with VERY little success.

Going to order parts for stuff mentioned above. Ada is out of that mic board, but they are plentiful on Amazon by other vendors.

Does anyone have recommendations for values of that attenuator circuit Gerald posted (R1,R2,C1) above. I’m a little leery of using the MOVI as a fuse :-).

Also issues with THRESHOLD, anything above 5 and it is stone deaf. I haven’t been using the internal mic so that may have something to do with that.

The main reason for the need of an external mic is that I can not have electrical stuff and wires spread on the bed. Mic needs to be mounted on the safety bar which is about a foot or so from the person talking.

Working with someone else here to see about being able to use a bluetooth headset which seems like it would be ideal, Using something like the motorola H730 (long battery life, noise canceling).

One of my MOVIs has a dead internal mic, thinking on what was said above, removing that, put in a jack and attach an electrit mic might be a plan too. Cable only has to run about three feet.

My biggest problem is time, doing caregiving 24/7 :-/. Working on this as I can.

Again, THANKS to all on this thread!!!

Vic.

43

Vic,

Here is a general description of attenuators with formula!

http://www.epanorama.net/circuits/line_to_mic.html

Gerald

44

So both Gerald and I have posted 2 separate links to a 40dB attenuator circuit diagram so you should be good to go there.

I asked Gerald once about the possibility of just desoldering the built-in microphone and replacing it with a jack, but he wasn’t a big fan of that idea for some reason. In any case, if your mic is broken on a MOVI board anyway, could be worth a shot.

Dylan.

45

Thanks folks!

Things have gotten hectic here and I am going to be slow responding for a while, sigh…

I did get a pile of those mics I have accumulated together and attempted to make a video, so far whatever I am doing with that isn’t suitable to show problems, working, lack of experience with it, need to play with it more.

First mic (lapel) I dug up did rather well other than chopping off beginning and ending of spoken phrase rather regularly (they all seem to do that).

Still having a problem with additional spoken phrases being noticed, it ?seems? like there has to be some delay between commands as ?MOVI? ?Due? is not ready to receive a second command right away. Working on that too. Possible there is some parameter involved?!?

I got the ada mic/amps today, I’ll try to get at them soon…

Also of interest, I got a stereo to mono 1/8" adapter and tried out the wireless headset that goes with that tour guide amp thingie. That seems to have possibilities. The headset has +/- keys that allow you to adjust the volume. No idea what the battery life (usb charge lithiums, I think for both the headset (transmitter) and receiver). Need to play with this some more. That I am sure is hackable, but it would be nice if one didn’t have to.

Dylan: Gerald says to ask you about a video you have that deals with varying noise in an environment, that might be useful with background noise (TV, etc.) in the “production environment”. Please and thank you?!

Coffee breaks over, back on my head :).

Thanks gain all!

46

Any non-powered microphone will do that - either not hearing you at all or cutting off beginning and end of phrases spoken.

I don’t yet have a video of my MOVI in the field with a noisy environment. I think the only videos I ever took were shared with Jared in an effort to figure out why MOVI was hearing an MP3 response I would play when the callsign was recognized (to replace the BEEP-BEEP) even though I coded to not have it listening at that time. Never did figure that one out, went back to the BEEP-BEEP response and just left it.

I will try to make a video soon - I have been meaning to for a long time now, but never prioritized it. Now that I know someone wants it, that will bug me enough to get it done. Unfortunately the car is in the shop right now (AGAIN!) so it could be a bit yet. Better be soon though because it’s going to climb over 100F every day where I live within a month! Too hot to drive with windows rolled up and AC off (Window noise or HVAC fans make MOVI unusable).

Dylan.

47

Hi all,

Just want to make sure, do you all think this external mic would work?

https://www.amazon.com/dp/B00IP0ST78

I am building an enclosure for the setup, so would like to use an external mic.

Many thanks!
Cheers,
TG

48

TG,

You definitely need a stereo to mono adapter. Other than that, I think it should be fine.

Gerald

49

Would this one work?

Thanks so much for your time, just wanted to make sure this adaptor works the other way around as well.

50

Yes, most likely! (haven’t tried it)

Gerald

51

Got the adafruit mics and have had a little chance to play with one.

Even with the lowest gain set (40db) it is still problematical. I added the 40 db attenuator which seems to make no difference at all.

Ahead of that is a 100uF electrolitic and a 22K resistor feeding a 100uF electrolitic cap to the MOVI mic input that makes it work at all.

Interesting though, with just the resistor /cap arrangement I can now get feedback from voice debug out in the hall and around the corner. Got to be closer to get MOVI to respond though.

Having fun now… WIll putz some more when time permits.

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