9V, 555, Relay, Photocell, and 500Hz Frequency

[ChristopherTate]

Hello,
New to the forum, and electronics. Actually, I'm an artist working with basic electronics for my senior thesis and I have a schematic I've been working on that I can't seem to wrap my head around.

Here is what I am trying to accomplish.

I have 40 small speaker elements that I would like to use. Each element will be connected to an individual 555 astable oscillator, you know the one, the timer, flasher, simple frequency, square-wave generator. Here is a pic just in case:

**broken link removed**

Anyways, I would like to run each circuit with a 9V battery that is connected to a 5V regulator. Additionally, I would like to make use of photocells to control the on/off state of the circuit, so it can be turned off by simply putting it in the dark, total darkness I should say. The oscillator should also generate a frequency within the range of .5-500Hz. (I've been connecting CDS cells in place of the 68K resistor to vary the frequency.) I understand the circuit as functioning like so:

9V battery > 5V regulator to conserve power > NPN Transistor or relay that
either opens the circuit, or closes it > and powers the astable oscillator
555 circuit > fed into the speaker.

Could someone assist me with a simple schematic of all this? I will be using a prototype board to put this together, I've thought of printing my own pcb, but given the amount of time I have left, I can't risk it.

I would be forever indebited to whomever can help me with this.

Thanks,
Chris

 

[ChristopherTate]

I didn't even think about it, but I think I'm going to use tip-switches instead, offering a better, more economic, solution to the the relay. Space is paramount with this application as the circuit and battery must fit inside a very small container. I'm still interested in hearing what you guys, and girls, have to say. Please, help

 

[ChristopherTate]

Actually, maybe this isn't the best option.

 

[on1aag]

555

Hi Christopher,

I would skip the voltage regulator because it consumes power and you
don't actually need one for battery operated circuits.
In order to save even more power you could replace the 555 with the
cmos version, the ICM7555. And if you wish to switch it on and off
with a light dependant resistor you could use the reset input, terminal 4,
to do so. The LDR should be connected between the supply voltage and
terminal 4 and another resistor from terminal 4 to GND. You can even
switch them all on and off with one LDR and one ordinary resistor.

on1aag.

 

[ChristopherTate]

on1aag.

Wow, thanks for the response. I'm a little confused though. Are you saying I can do this?


Vcc
|
|
V
LDR ----> R1 -----> Vdd
|
|
P4


Could you simplify that a little bit for me? Sorry, I'm still getting used to visualizing circuits.

Thanks again!

Chris

 

[ChristopherTate]

Okay, I got it working with the one, totally cool. How do I do it with all of them? A friend told me that I can power all of them with a computer power supply since they have multiple +5V rails.

Now the NE555P that I'm using has a 200MW max input which is feeding each 10W speaker. If I am planning on powering 40 of these lil circuits with the one power supply, how do I go about hooking it up?

Wow, this is getting pretty silly, I think i should take a step back and clearly define what exactly is happening...

To start, I am using the Apple Pro Speaker, the clear globe and would like to attach the oscillator directly to the leads of each speaker element, creating a ticking, buzzing, square-wave sound. The speaker, from what I've been able to find, is a 10W Harmon Kardon element capable of 7Hz to 20kHz. I'm not fresh on the math for the necessary power needed, or the drain, so I'll need a lil help on that.

I would like to connect the oscillator, which currently has an LDR in place of R2 which varys frequency, to either a 9V battery or an external 5V power supply (the computer power supply).

The circuit should also maintain a light sensitive switch, which you have illustrated above. However, I have 40 of them, so if there were a way to control all of them with a single switch, another LDR, that would be great.

 

[audioguru]

The 555 is not a power amplifier. It is an oscillator.
Speakers are driven by power amplifiers, not oscillators.
The max allowed output of a 555 is 200mA, not 200mw. With a 5V supply the max current is 219mA into an 8 ohm speaker which might destroy the 555.
The speaker's power is a tiny 192mW.

Speakers use an AC signal from a power amplifier. The output of a 555 is DC pulses, not AC. The DC might destroy a tweeter speaker.

A 9V battery with a 5V regulator would make sound from the 555 and speaker for a few minutes before the battery will be dead. Most of the battery's power will heat the regulator and the 555.

Why use many speakers? A single speaker driven by an power amplifier can reproduce an entire orchestra and an entire chorus of singers. Let all the 555's feed a mixer circuit that drives the amplifier.

 

[ChristopherTate]

Audioguru -
Thanks for the reply. In response, i must add that I've been using the 555 as an oscillator that generates a square wave for some time now. Please see the circuit above. Also, there are numerous 555 tone circuits that make use of much smaller speakers, see siren circuit and 555 tone generators. Also, I have been using a similar circuit that makes use of bill bowdens tone circuit:

**broken link removed**

which actually supplies an AC current to the speaker.

Furthermore, I've built at least a dozen prototypes, with and without 5v regulators, and all of them have lasted months and months. I have 3 right now, with 5V regulators (which I don't need *thanks on1aag) that I built 8 months ago that work fine.

As for needing 40, well, that's part of my experiment. Each one will be an autonomous entity, hence needing an individual circuit for each. I am not looking to reproduce an entire orchestra or chorus, i'm looking to create an army of clickers.

Thanks

 

[audioguru]

I hope that you use a coupling capacitor to avoid DC in the speaker and use a series resistor to reduce the current in the speaker like both are in Bill Bowden's second circuit.
Of course, the battery has a high drain only during the sound that is produced.

 

[Hero999]

Get rid of the resistor and use a 2:mu:F capacitor in series with the speaker.

 

[audioguru]

A 2uF capacitor in series with an 8 ohm speaker will cut frequencies below 10kHz. The output of the lower frequencies will be very low and shrill-sounding. It is a simple crossover network for a super-tweeter with an output of 10kHz to 20kHz.

 

[Hero999]

Maybe I've misread this, the schematic in the link posted said it was a 1kHz tone generator so I selected a capacitor value that will limit the power dissipation to 100mW which is the typical maximum for a small speaker.

Reading the thread again, I think this was wrong, it looks like he wants to make a musical instrument. There are cheaper ways of building a huge number of oscillators, you could use a load of hex Schmitt trigger ICs( to get siz oscillators per chip), mix all the outputs together and put them into a small power amplifier.

 

[ChristopherTate]

Hey guys - Thanks for all the great responses. I'm sure that a lot of the means that you're suggesting are fantastic. At this time, I'm running with bill bowdens circuit, throwing an LDR on in place of one of the resistors, to create a variable tone, and using a cap in line with the speaker to prevent DC current. I'm also using a computer power supply to run these little guys, which seems to work fine. I'll post more pix as I move forward...

**broken link removed****broken link removed****broken link removed**​

Thanks again!

Chris

 

[audioguru]

A Christmas tree ornament that makes a noise when you make a light or shadow on it? I think Christmas is finished this year.

 

[ChristopherTate]

hahah, thanks