Sound level cutoff meter

[stuee]

Hi, i asked for help to make something like this a while ago but instead of helping i was getting questions why, why why.
Ill tell you why.
I have a small function room for 40 people and it has a sound system and jukebox included. On a few occasions ive turned up and found the soundsystem louder than the council agreed me to have it. there is no control over this without removing the knob but then it will be at a set volume.
I just gave up on the idea to control the volume level but now ive had a complaint from someone local via the council and i need to act fast to show them this has been on all the time so its just someone moaning (as you get)

What i wanted to do was, i have a mixer that all the music sources goes to and then to the speaker, I would like to make something with leds to show the volume level, when it gets over a certain say 4 green leds it goes into orange and a small flashing light comes on ontop of the mixer. If it goes into red a 5 second timer comes on and if its still in the red after 5 seconds it turns off the mixer for 30 seconds / then they turn down the mixer.


the mixer has a 4 pin round power socket and the power supply ready 2x 18v/ 500ma.

My thought was.
A level indicator > timers > relay to turn off the mixer either in the 240v stage or after the transformer in the 18v stage.
any thoughts help, ideas, schematics or links would be appreciated. thanks

 

[stuee]

Something like this.

 

[stuee]

i could use this for both the 10 second and 30 second timer so i can adjust the times as need be but not sure how to make into seconds instead of minutes. Also i would scrap the led etc and just run that to the relay.
https://electronicsclub.info/p_timer.htm

 

[MCU88]

It doesn't make any sense what you are saying.

 

[stuee]

what doesn't make any sense? i need to make something that shows my customers who hire the venue the when in green the sound is fine, if its turned up too much it goes in orange and a strobe flashes, if its too loud it goes in the red and triggers a 5 second timer (to skip any bass or loud hits in the audio) if its solid in red for 5 seconds it then triggers the next timer which disables power to the mixer hence no sound to the speaker, for 30 seconds. It comes back on after 30 seconds and when they know this is on they wont turn it so loud again.
Did that make better sense?

 

[alec_t]

Wouldn't it be simpler just to have a preset volume control hidden away somewhere, so that whatever the main volume control is set to the sound level can't exceed a limit of your choosing?

 

[MCU88]

You can make some automatic volume attenuation... the timers I do not see how this makes any sense...

I see lack of coherency with what you are suggesting in your schema. It is like you are suggesting some sort of closed loop control that is completely bananas.

Don't get me wrong, I mean what you do need is closed loop control, but not with timers to switch the whole thing off... take caution with closed loop control because it may oscillate...

You can make an VU (Volume Units) -- meter and if the red led comes on then automatically throttle back / attenuate the volume...

 

[stuee]

I need something to show the council if they come in that there is a sound monitoring system installed. I tried limiting the audio but there is always 1 person at a function that knows how to bypass or adjust.
The way i was wanting to do is a completely independant curcuit that just turns off the power to the mixer if they dont keep to the rules. I need it to give them a warning becasluse you dont want to be in a function and the music keeps turni g off with no warning.

 

[MCU88]

I need something to show the council if they come in that there is a sound monitoring system installed. I tried limiting the audio but there is always 1 person at a function that knows how to bypass or adjust.
The way i was wanting to do is a completely independant curcuit that just turns off the power to the mixer if they dont keep to the rules. I need it to give them a warning becasluse you dont want to be in a function and the music keeps turni g off with no warning.

Like I said amigo... 'automatic volume attenuation'

OR...

You could have an master volume control in the form of an POT, set it and hide it in an small black box whereas you would need an screwdriver to remove the screws and open it...

 

[Reloadron]

Wouldn't it be simpler just to have a preset volume control hidden away somewhere, so that whatever the main volume control is set to the sound level can't exceed a limit of your choosing?

That is what I would consider. Place a limit on the volume control pot. When the volume control pot is at maximum for example the volume will not exceed acceptable limits. Could this all be done as you mentioned? Yes, but a pile of parts and a lot of work for nothing.

Ron

 

[stuee]

It need to be a visable thing, i tried setting the volume inline once so it wouldn't go louder but then started getting bad reviews from patrons on the webpage saying its a quiet and poor quality sound system. If they can see something warning them and then turn off or turn down auto (perhaps to quiet untill they lower the volume then it goes back to normal volume volume??) this way they feel incontrol and knows it can go louder but limited because of the law

 

[KeepItSimpleStupid]

I see nothing fundamentally wrong with your idea except purests would want to actually measure the level with the appropriate weighting.

Here's https://www.google.com/url?sa=t&rct...Cqq3Pu4unVpX3Dw&bvm=bv.92291466,d.eXY&cad=rja

a kit for a VU meter. So mount it where the performers can see it, in the opposite wall where people are facing. Measuring is your first step, otherwise you get, I didn't know it was too loud.

the next step would be tapping into VU meter (hopefully it has a bar mode) and doing an exceeds 0 db for a certain amount of time. Let's say 1 minute, the system turns off for 1 minute. A count-down timer would be perfect, now showing the time until reset or the time until the system can be manually reset to allow for unattended operation. You don't want the system to come on/off every 1 minute.

 

[Reloadron]

It need to be a visable thing, i tried setting the volume inline once so it wouldn't go louder but then started getting bad reviews from patrons on the webpage saying its a quiet and poor quality sound system. If they can see something warning them and then turn off or turn down auto (perhaps to quiet untill they lower the volume then it goes back to normal volume volume??) this way they feel incontrol and knows it can go louder but limited because of the law

Oh a visible thing? We can do that easy:

OK, if you really want a circuit to do as you ask then I would start with a chip like the LM3914 or as KISS mentioned, for the purist, the LM3915. The 3914 id linear and the 3915 is log.

LM3914 Data Sheet

LM3915 Data Sheet

The outputs on either chip sequentially go Low as the input signal increases. Use that signal to drive a One Shot which drives a small relay (or whatever works for you) to disable the audio for a preset time. Personally I like the sign as the people should be bright enough to interpret a simple sign and respect the rights of others.

Ron

 

[KeepItSimpleStupid]

The sign and the ability to monitor hopefully would work.

Do not turn the sound system level above 0 db unless you want everybody to lose the privileged of the sound system entirely. Violations will result in more effective countermeasures an/or the loss of the use of the room. See the contract you signed.

Timers such as these: https://www.redlion.net/product/cub5-preset-timer-cycle-counter-backlight-display exist and MAY work. This one apparently has an output when the amount of time preset is exceeded. You can also probably get resettable hour meters without the timer for cheap. You can buy stuff and use some "glue logic" to put it together.

The "glue" in this case would be OR-ing the left and right channels and getting an output above 0 db to gate the timer and a Key reset and possible tamper alarm.

If it doesn't work, move onto the next phase where power is removed and manually reset. If a second comparator is available, then say after 15 minutes, power to the sound system stays off and cannot be reset.

Contract example:
If the amount of time exceeds 5 minutes of time above 0 db you will be charged $100. The $100 will be held in escrow until the event is over and the meter read and reset.

==

You can't enforce something that you can't measure. You would be measuring the input to the amplifier. That only works if the amp has fixed gain.
Sound or noise levels have an ear perception level associated with them. Defaeat would be removing power to the monitoring gizmo.

In your design, think of how one might defeat it. There are breakers with electronic trips. You could mute the amp with a wireless signal. UPB or Insteon is possible too. You don;t have to really kill power to the amp. You could mute the signal wirelessly or through power line communications.

I'm just "thinking outloud". It may not be an effective design, but rather a place to start. Commercial products with "glue" is generally easier to maintain.

 

[stuee]

I have put this together from some links you have supplied.
I know just putting this together wont just work as i need to work out the timers which is where i ask for detailed help.
I want the first timer to kick in when the first red led lights, it has to be activated for more than 5 seconds (but would like adjustable time) if the time exceeds 5 seconds then it sends a trigger to the second timer that triggers that to output to the relay and disable the relay for a fixed time (30 seconds but would like adjustable from 5 sec to 1 min)
Please dont abuse me about how i have put the circuit drawing together, im not expert, thats why im asking the experts!




To answer a question or 2.
The venue is not manned so when the music does go high no one is here to monitor it hence the auto service.
In the hire agreement i do have a section
"
6. ENTERTAINMENT & MUSIC - Music must not be excessively louder than the ambient noise of the room. If we receive noise complaints, we will regard this as a serious breach of the hire conditions and end your function immediately. If your booking involves adult entertainment, you are required by law to close the curtains so not to be visible to passers-by. "

But again when noone is here to monitor there is not much you can do,

Thanks

 

[Reloadron]

Just right off the top where you are driving a relay with the 3915 chip. You may want to have the 3915 drive a transistor to in turn drive the relay coil. Relay coils will also need some flyback diodes but overall, you have the idea. Tomorrow I'll better look at this and maybe come up with a few ideas for you.

Ron

 

[stuee]

Thank you very much ron. Ive just installed eaglepcb too so i can draw out properly and also got an etching kit already and will tunr this into a proper schematic and plans in case anyone else wants to use one

cheers

 

[KeepItSimpleStupid]

Hey, not a bad first cut. Initially, I see:

1) Bypass caps should be 0.1 to 1 uf and usually ceramic or possibly tantalum. They are located close to the ICs.
So, the LM gets one, the OP amp gets one and the timers get one.
2) I don't think a 9V battery source will work. It would have trouble driving a relay. 9V relay are uncommon.
You might have to go with a sealed lead acid or LiPo.
3) Coil suppression diodes are missing. They protect the semiconductors driving the coils.
4) In bar mode, you only have to detect the lowest LED, not all three. In DOT mode power consumption is reduced and you do have to detect more LEDS being on.
5) The datasheet says the cartoon isn't accurate and provides a mini schematic of the output circuit. For the LED's you'd like to monitor. So, I would use a series connected optocoupler with the LED with either FET or a transistor output. That gives you an uncommitted NPN transistor usually.
6) Things do get messy when trying to do timing after about 4 seconds. The capacitor selection is critical and the timing accuracy gets bad. The tolerances of electrolytic caps are to blame/ There are better ways of doing long delays. See **broken link removed**
7) You might look into the 7555 timer. A lower power cousin.
8) I did not look at the set/reset.

Impressed,otherwise, for cut/paste. Let's see what others have to say.

As I said, I tend to go overboard and then simplify. You did, maybe unknowing use some of the out of the blue suggestions.

 

[audioguru]

Your circuit triggers the 555 on the momentary peak sound level. It might be from a hand clap, a foot stomp or a cough. What about laughter?
Don't you want it to trigger on the average sound level?

 

[stuee]

Audio guru, the reason why the first timer is set at 5 seconds (doesn't have to be accurate) is to deal with the problem of claps, laughter or bass hits. If the timer receives the trigger for longer then 5 seconds +/- then it triggers the next timer to turn off the sound.
This is one of the reasons i wanted the timers variable so i can mess with the timing and even move it to the second red led.
Keep it simple.. Thanks, some of that made sense. and ill wait for more input too, i dont think my knowledge is good enought to jump in and start adding bits etc