556 timer

[zachtheterrible]

Hi there. I want a BEEP BEEP BEEP for my alarm system. This would require two 555 timers: One to set the audio frequency, and one to set the intervals of beeping. Since I have a 556, I would like to do it with that. Anybody have a schematic or anything? There is a lack of 556 schematics on google image search.

 

[jrz126]

I believe a 556 is just 2 555's placed in a single package, only differene is that there is a common Vcc and ground going in. So you can just use regular 555 schematics.

https://www.electro-tech-online.com/custompdfs/2005/06/lm556.pdf
**broken link removed**

I also have this little 555 calculator thingy that I uploaded on here awhile ago...
not sure if you need it or not but Ill give it to you anyways

 

[zachtheterrible]

Oh, I didn't realize that it is LITERALY two 555's. I thought there was some sort of difference, but that makes things simpler :lol:

thanx

 

[Jay.slovak]

I know 556 is much cheaper, but I would use 12F629 to do the job :lol:

 

[zachtheterrible]

I know 556 is much cheaper, but I would use 12F629 to do the job :lol:

What be that?

 

[Jay.slovak]

I know 556 is much cheaper, but I would use 12F629 to do the job :lol:

What be that?

Using small 8-pin PIC is a nice way how to build Beep Beep thingy. It costs about 2$ (Depending on location, may be cheaper). And you can use the other 5 I/Os for other purpose..

PS: I am not trying to force you this, I just use the PIC wherever I can, because it is simple to me. 8)

 

[Misterbenn]

Jay.slovak!!!
a PIC for such a simple task!!!
i ask you what is the world coming to!
PICs are good for development reasons yes but in this case i dont think there seems to be much call for development, and the 555 option wouldnt take up that much more space or power.

i'm telling you PICs and Hardware are like a calculator and good old fasioned pen & paper, sure calculators are easy and fast, but its important to keep the old skills going, some situations do call for them.

sorry i guess i'm reluctant to let go off hardware, but its the next logical step i guess, like transistors took over from valves.

 

[David Bridgen]

Hi there. I want a BEEP BEEP BEEP for my alarm system. This would require two ..... timers: One to set the audio frequency, and one to set the intervals of beeping. ..... have a 556, I would like to do it with that.

Both sections as astables. The lower frequency one's output connected to the higher frequency one's RESET pin. The latter will then be switched on and off at the rate set by the first.

 

[zachtheterrible]

Hooray, it works :lol:

thanx david, that helps. I had the output of the first stage connected to the voltage control pin of the second stage, it was giving me: dah doh dah doh, it sounded like the police cars in England :lol:

Now I just need to make it louder. I have an 8 ohm speaker connected directly to the output. My supply voltage is going to be +5v. Just how loud can I get it to go by amplifying it with a transistor? I'm not looking for ear-splitting loud, let's say I want to be able to hear it over a moderately loud radio, just to give an idea.

 

[audioguru]

Hi Zach,
With your 555 trying to drive an 8 ohm speaker, its output current is way beyond its maximum. You are lucky it survives.
Your 5V supply limits the output of a transistor that could drive the speaker, so it won't be much louder than with the 555 driving the speaker directly. A re-entrant horn speaker (used in cheap paging systems) is much more sensitive than an ordinary speaker and would be loud enough when driven by a transistor. If the transistor saturates and cuts-off, the 8 ohm speaker's "on" current is nearly 600mA and its average power is nearly 1.5W. :lol:

 

[zachtheterrible]

I just dug up an old self-driven 85db piezo buzzer that i have. Needless to say it is plenty loud, and I only have to use a 555 timer.

I'm glad I figured out how to do this though, it'll come in handy in the future.

Thanx for all the help :lol:

 

[Someone Electro]

try conecting the output of the first one to the voltage conrol pin of the second whith an resistor and cap to make it sine wave.It will make the second timers freq. go up and down.It will freqency modulate to the signal its geting in the voltage conrol pin (this is pin 5 on an NE555)

Sounds like a siren.

Or this i tryd i made it oscilate in audio rage on a rely small cap.Then i put to wires out where the cap was and the harder you sqoize the wires in your fingar the more capacitence you get and a lower freq..You can make sounds like the door is squicking. (i had fun whith that one)

 

[Nigel Goodwin]

Jay.slovak!!!
a PIC for such a simple task!!!
i ask you what is the world coming to!
PICs are good for development reasons yes but in this case i dont think there seems to be much call for development, and the 555 option wouldnt take up that much more space or power.

The advantages are many, for a start all you are using is ONE 8 pin IC, and NO OTHER COMPONENTS!.

So the 555 option would take much more than twice the space, and considerably more power - although if you're generating audio, the power feeding the transducer should pretty well cover any power the chip takes.

For a simple beeping circuit it might look like overkill, but a 12F629 makes an excellent replacement for many 555 designs - reducing component count and vastly improving performance - try and get a 555 to give a day or a week delay? :lol:

However, both options are perfectly valid! - as are various other ways of doing it.

 

[eblc1388]

It seems the use of PIC is becoming inevitable.

Today I tried to find an IC which do the interfacing of 16/20 keys to the microcontroller. It is the 74C922 and 74C923. The price they asked for is about six pounds plus postage.

One can use a PIC to do just that for 1/5 of the cost.

I think in the near future PIC code library would contains many many familiar ICs like the above and those that are obsoleted like say the 8-input priority encoder.

 

[Jay.slovak]

It seems the use of PIC is becoming inevitable.

Today I tried to find an IC which do the interfacing of 16/20 keys to the microcontroller. It is the 74C922 and 74C923. The price they asked for is about six pounds plus postage.

One can use a PIC to do just that for 1/5 of the cost.

I think in the near future PIC code library would contains many many familiar ICs like the above and those that are obsoleted like say the 8-input priority encoder.

Yes, history repeats... I think same situation was with GALs and TTLs, TTL was replaced by GAL, and later GAL was replaced by MCU... Having one universal MCU sure is better choice than to have a bunch of standart IC's, atleast that's my oppinion.

 

[Someone Electro]

I dont think zatch has used MCUs before so its wod be an 555 timer for him.

The 555 timer is probobly one of the most known IC around

 

[zachtheterrible]

After this project i swear I'm going to get me a PIC! You can do so much with them, and I know that if I learn how to use them, I will be able to greatly increase the things that I cna do.

 

[Jay.slovak]

After this project i swear I'm going to get me a PIC! You can do so much with them, and I know that if I learn how to use them, I will be able to greatly increase the things that I cna do.

That's the spirit I want to hear every day!!! :twisted:

 

[Someone Electro]

Yep you can do a lot of stuff whith PICs

I heard that working whith an IDE HD is realy easy whit an MCU .The huge number of pins dosent say that to me (I have an old 30GB HD right here)

Jay you shod be named "PIC junky" since you know a LOT about PICs

 

[Someone Electro]

Oh and zath dont burn the program on them whith an microwave.(Your prety interested in microwaves)