I can be taught! But in the mean time...

[the_drewster]

I know there are so many novice questions on these forums, can you answer one more?

I want to create a sound activated LED, that is activated by *any* noise, and ideally the LED will stay on for say 30 seconds before switching off. The most important aspect is that it needs to be as small as possible as it will fit within a tiny space. This also means that it will need to run of tiny button batteries. I have read the many threads in the forum that have asked for similar advice as well as having found many circuit diagrams on the net, but they all have one of the following points:

1. Either the components seem many and the circuit very large
2. Or they run off large batteries.

I remembered them keyrings from the 80's that beeped and flashed when you whistled, so I bought a couple off ebay and took them apart. I was amazed at how minimal the circuitry is, it's ideal, but the led flashes too many times and of course it beeps, and it only activated when whistled at. I have inserted an image below.

**broken link removed**


So here are my questions:

1. Is it possible to modify the circuit above so that it doesn't flash.
2. Is it possible to modify the circuit above so that it stays on for a while?
3. Is it possible to modify the circuit above so that I can get rid of that irritating beep?
4. Is it possible to modify the cicuit above so that it is activated by any noise and not a whistle? Where is the filter that determines the frequency?
5. Is it easier to make one from new?
6. What's that big black blob? Is this some kind of microcontroller?


I have got my Electronics for Dummies book but in the mean time a point in the right direction woud be very much appreciated.

Thanks

D

 

[Andy1845c]

1. Is it possible to modify the circuit above so that it doesn't flash.
2. Is it possible to modify the circuit above so that it stays on for a while?
3. Is it possible to modify the circuit above so that I can get rid of that irritating beep?
4. Is it possible to modify the cicuit above so that it is activated by any noise and not a whistle? Where is the filter that determines the frequency?
5. Is it easier to make one from new?
6. What's that big black blob? Is this some kind of microcontroller?


I have got my Electronics for Dummies book but in the mean time a point in the right direction woud be very much appreciated.

Thanks

D

I think its going to be awful hard to modify the circuit in your picture. Theres really no room to add or change anything.

The pictures shows some button batterys, an LED and a black blob. Whats on the other side?

I'm not sure what the blob is. It could be covering some unknown SMD component. The traces appear to run into/under it.

What circuits have you found? Somthing that seems big can somtimes be condensed with good PCB layout and SMD parts. Not somthing for beginners though.

 

[audioguru]

My daughter bought a keys finder. She brought it to me and said, "Dad, the thing beeps when I talk and it beeps when the TV is on. Can you fix it so it beeps only when I whistle?". I whistled and it did nothing. Then I whistled loudly and it still did nothing. My daughter was pretty far away and started talking quietly to my wife and the thing beeped. It is cheap Chinese junk!

I made a Sound Level Indicator project. It has 10 LEDs (actually 20 but 10 groups of 2 in series). It can indicate the sound of a pin dropped on the floor in the next room. Its first LED lights if the furnace or fridge is running and if they are quiet then I must hold my breath for no display. It has a range of 50dB so it also indicates loud sounds.

You must determine how much sound level is needed for your application.

Tiny button batteries can light an LED dimly for maybe 30 seconds. Then they are dead.

 

[KMoffett]

...
So here are my questions:

1. Is it possible to modify the circuit above so that it doesn't flash.
2. Is it possible to modify the circuit above so that it stays on for a while?
3. Is it possible to modify the circuit above so that I can get rid of that irritating beep?
4. Is it possible to modify the cicuit above so that it is activated by any noise and not a whistle? Where is the filter that determines the frequency?
5. Is it easier to make one from new?
6. What's that big black blob? Is this some kind of microcontroller?


I have got my Electronics for Dummies book but in the mean time a point in the right direction woud be very much appreciated.

Thanks

D

6: the black blob covers a lot of micro electronics.

3. my guess is that if you cut one wire (or both...what the heck) to the beeper the unit will still work, but won't beep.

1. & 2.: if you use this as a "transducer" and connect the led output to a monostable, like a LM555C through a transistor level shifter, you can drive an unblinking LED and extend the time.

4: Don't know, but probably not.

5: Don't know.

My 2 cents.
Ken

 

[Mikebits]

3. my guess is that if you cut one wire (or both...what the heck) to the beeper the unit will still work, but won't beep.

Then how will it detect sound? It looks like it serves as both the beeper and transducer.

 

[KMoffett]

I think I thought...there was a sound pickup on the other side. So...to quote Emily Litella: "Never mind!"

Ken

 

[Mikebits]

I think I thought...there was a sound pickup on the other side. So...to quote Emily Litella: "Never mind!"

Ken

Was that Rosana Dana something?

Don't worry, I thought the same thing at first glance.

 

[Hero999]

I'm not sure what the blob is. It could be covering some unknown SMD component. The traces appear to run into/under it.

It's a chip on board.

The silicon die is wired directly to the PCB and is protected with a blob of resin. Mounting the chip directly on the board saves the expense of packaging it separately. This method of encapsulation has been popular since the 80s when the first really cheap electronic toys, watches and calculators were produced.

 

[killivolt]

Looking at the way the circuit appears to be wired. Could be possible to have a diode in series which would allow the transducer to influence the processor and still block it from sounding ?


kv

 

[Mikebits]

What about a cap?

 

[k7elp60]

With a couple of A76 alkaline batteries, a cmos 555, a low voltage op amp such as TS972, and a few parts a circuit could be built.

The thumb nails of a haloween badge I made over a year ago is shown.
The whole circuit runs of a CR2032 coin size lithium battery. The Boo Badge B image is of the battery and the control circuitry. It has 2 cmos 555 timers and a 4017 counter. The other board has some 2N3904 drivers and believe it or not each letter has 4 or more LED's in parallel. The letters actually flash on and off and they are charlie plexed. One timer feeds the clock input of the 4017, and the other drives the reset line. The same battery has power the badge for about 8 hours in the past two haloweens.

 

[audioguru]

The output current of a CD4017 is typically 3mA into an LED with a 5V supply. It is less than 1mA with a 3V supply. The minimum supply for a CD4017 is 3.0V so it might stop when the battery is slightly used.
LEDs are pretty dim with less than only 1mA.

The output current of a 74HC4017 is typically 47mA into an LED with a 5V supply. It might be 30mA with a 3V supply. Its minimum supply voltage is 2V. The LEDs will be very bright like my 3V Ultra-bright chaser project.

 

[andy257]

I want to create a sound activated LED, that is activated by *any* noise,

D

What do you mean by "any noise"? You might want to define what noise level / frequency you want to trigger your circuit. Saying any noise is not that helpful, you may as well just use a battery, resistor and led if you want your circuit to work with any noise.

 

[k7elp60]

Audioguru is correct about the CD4017 supply voltage. I have been lucky as the ones I have have been working below 3V. With the 74HC4017 It appears that I would not need the 2N3904 transistors as LED drivers with it. Thanks Audioguru for the information.
Here is the schematic of the Boo Badge. The LED's are red high MCD and are real bright with a few MA.

 

[audioguru]

I made a 3V Ultra-Bright Chaser project using high-speed Cmos ICs and the LEDs chased around and around and around ... no-hum very boring.

Then I made a 6V one using very bright 3.2V green and blue LEDs and made the LEDs chase around a few times and stop for a pause. Then chase around again then stop for another pause.

Then I converted the 6V circuit to 3V.
The circuits have a speed control and a brightness control. The brightness is done with PWM. The battery lasts for a very long time.

 

[killivolt]

I made a 3V Ultra-Bright Chaser project using high-speed Cmos ICs and the LEDs chased around and around and around ... no-hum very boring.

Then I made a 6V one using very bright 3.2V green and blue LEDs and made the LEDs chase around a few times and stop for a pause. Then chase around again then stop for another pause.

Then I converted the 6V circuit to 3V.
The circuits have a speed control and a brightness control. The brightness is done with PWM. The battery lasts for a very long time.

Guru I would like to build this for my Darkpumpkin project. I want a smaller pumpkin to light up inside to make it look like it's on fire. This would work perfectly.

What do I have to do to get the specs. First born child maybe ?


kv

 

[audioguru]

Hi Killivolt,
I don't want your first-born child unless she is .... never mind.

Here is the parts list and Veroboard layout for my 3V Chaser-2.

 

[killivolt]

Everyone needs a Good Slave.

Hi Killivolt,
I don't want your first-born child unless she is .... never mind.

Here is the parts list and Veroboard layout for my 3V Chaser-2.

Thank you.

Downloading in T-minus 10.

kv

P.S. She is a hottie. But, her Mom won't let me claim her.

You'll have to settle for a slave (2nd born) to work at the soldering Pot. Just keep him in a good supply of cigarette's he'll work cheaply and is found to be quite funny when relaxed.

 

[the_drewster]

Well thank you all very much for the replies. I'm confused! I get the impression from some responses that it's a tedious job, and from others that it's not.

If I'm less stringent on the requirements would it help?

Here's a new list:

1. The light just has to come on for a while and then off, or it can flash for a shot while, which ever is easier.

2. It needs to fit in a tiny tiny place.

3. When I say activated by any noise, I really mean any noise. Like a shout, a clap or a fart. Hee hee, a fart activated light

There is nothing on the back. Yes, the speaker acts as both the transducer and speaker. Incidently, if I trigger it with a whistle and then quickly disconnect the speaker, the led continues flashing for a while. Does this mean a signal is travelling to and from the transducer? Can it not be limited to go in only one direction, or does it not work like that?

What do you mean by "any noise"? You might want to define what noise level / frequency you want to trigger your circuit. Saying any noise is not that helpful, you may as well just use a battery, resistor and led if you want your circuit to work with any noise.

How about the mic? Is it easy to do then and make as small as the one above?


Drew

 

[audioguru]

You can't make the tiny black blob so you need a pretty big circuit board for all the parts for your fairly complicated requirements. The battery must be pretty big or you will need to replace it often.