Looking For a senative tiny MIC pickup for room

[CeaSaR]

I have a rough idea drawn out that gives enough adjustability to use an input from
1 volt to 4 volts at the speaker positive wire. I have not done much analysis except
to simulate voltages at each LED. It uses 1/4 of an LM324 for one speaker (channel /
station), allowing you to use 1 chip for all 4 receivers.



I ask those of the N&V board more knowledgeable than I to suggest any improvements
to make it work better. All ideas, suggestions and/or criticisms welcome.

Also, it would be good to know approximately what voltage you are getting at the
speaker leads when you have a comfortable volume level. That would help in coming
up with a better, more suited design.

CeaSaR

[Bob Scott]

Ceasar,
The LEDs are shown installed backwards. Since the - terminal of the LM324 power supply is ground, the LM324 can't sink current below ground.
The LM324 has a current limited output of ~20mA. I didn't do exact calculations, but I think the LM324 will run out of poop in that circuit.

How about the National LM3915 /LM3916 series? These are built as audio VU meter LED drivers? They used to be available at Radio Shack. Sample sircuits are on the data sheet. Radio Shack used to have the 10 LED displays too IIRC.

http://www.national.com/mpf/LM/LM3916.html

[CeaSaR]

Bob,

Absolutely right! I have no idea what I was thinking... Thanks for the catch.

I looked at the LM3915 (16) and they would definitely do the job. Seems they are
not available in small quantities. Bummer.

Let's find out what DC has or will have on hand to work with once he sorts through
the excellent good fortune of his Waffle House encounter. What a lucky guy!

CeaSaR

[directcurrent]

hay CeaSar, sorryfor the delay in getting back with you but My folk and I have had a another bad turn and it has been very hard on me, I have not sleep for about a week with their bad problems. I feel like screaming at the top of my lungs. THis project would have a lot of welcome effects on my brain tention. Going to drink me some hotcocoa and go to bed to get some sleep, I think. God Bless and hope you get some sleep also. DC.

[dacflyer]

hey, here is another idea.. i have collected a few of the microphones that were used on old car phones, that had the mic that mounted on your sun visor, they have a very sensitive mic that had an automatic self adjusting gain.. it would not work exactly as it with out some sort of power to the mic, but i popped one open and simply added on a coin cell battery holder, and attached the battery to the large cap inside the mic. the battery has lasted for 2 yrs now. i use it on my comp a lot. and i can talk from across the room with it..
if you need one, let me know.. sell or trade,, i have 1-2 i can spare.

[directcurrent]

Decfly give me til Tues and I may take you up. I am on a string bean bug and lately my candals a re burning at both ends.
How is fattevile these days? Use to do a lot of traveling thru with my x-wife to her mothers place. Glad that was over!! X turn in to a bad girl. More interested in money then me.
I will definate be getting back with you, O I forgot, How much you need?

[CeaSaR]

DirectCurrent,

I hope everything is going better for you. I found a circuit you could use instead of
the one I tried to design. You can find it through the link below:

http://www.discovercircuits.com/PDF-FIL ... ETECT1.pdf

I found the LMC7215 at MCM for $1.73 in quantities under 25. See link below:

http://www.mcmelectronics.com/product/N-92F367

Mouser and Jameco didn't have it.

Take care,
CeaSaR

[directcurrent]

Hay CeaSaR, sorry for the delay in getting back with you, Had some problem with the folks, house repair, my truck, and of all things I wind up in the hospital for four days. Things are going a bit better now but got to work up my strenght again and the heat here has held me back from working in the shop to much. We've have had 100, 102, 104 for nearly 10 days strait and thats not including the heat index making it in the 117 and 112 range all the way til 5:30 PM . and no rain.
I'am making time to follow up on your info, but I may get back on Monday. I have someone here helping me move my computer off the floor and on my new desk, I built, and set up my lighted chess board. O BTW I like the idea of the LED's Backwards, that way I can turn my eye balls around to see them giggle giggle.

[CeaSaR]

Glad you are getting back on your feet. The best news is you have your humor.
That means you'll do fine. Take your time, especially in the heat.

Take care,

CeaSaR

[CeaSaR]

Here's another audio meter you might be able to use.

http://www.mitedu.freeserve.co.uk/Circu ... umeter.htm

You might need more dropping resistance initialy if the speaker level is too high.


Hope everything is going okay for you and the folks.

CeaSaR