555 IC's Problem

Hello to all. I have a problem to creating square pulse by 555 IC. I want to create a simple square pulse with 50% duty cycle and 5000Hz. Actually my power source is less than 3 volts , but the minimum operation voltage of 555 is 4.5 volts. Is there another IC to creating simple pulse , or how can I do? Very Thank you.

Use a LMC555 ;)

Very thank you friend. :)

Sorry , But there wasn't LMC555 in our Country , Anything else??

The CD4047 will run as a monostable or astable oscillator. The oscillator runs at twice the output frequency so that it can be fed through an f/2 flip-flop yielding 50% duty cycle. The spec sheet does not show any data below 5V so I’m not sure how well it will perform.

Here’s the data sheet. Click the download link near the top.

Most any 555 will work. LM555 SE555 etc. Dwight

But in all datasheets,it has mentioned the minimum supply voltage is 4.5v???

OK, why do you have less than 3V to work with? Dwight

Because my pcb is small also I use a disk battery as my power source. I just want to create square pulse between 500 to 10000 hz, and .5 to 1 volt.

There are many circuits you can use to make CMOS inverters into RC oscillators. Look up 74HC4060.

Pff, if a normal chip like that isn't available...

But you can also use a ATtiny85 or something and write a simple sketch... Can run just fine @ 3V

Or if you have some transistors (2) and resistors (4) and capacitors (2), you can make a multivibrator type oscillator.

Edit - "if you have tubes(2)" :)

Sorry , But there wasn’t LMC555 in our Country , Anything else??

State your country, and we will find you a Cmos 555.
The Maxim ICM7555 is another Cmos version that works on a >=2volt supply.
Needs one cap and one resistor to make a 50% square wave.

I think ICM7555 is fine.Thanks But I don't know anything about it.Actually I have 10 switches that every one creates a kind of square pulse with different frequencies.for example 50,100,150,200,250,300,350,400,450,500 HZ with 50% duty cycle. Another question,Can I create all 10 frequencies by just one ICM7555?How? Thanks again.

Yes, with switched capacitors and resistors. You may want to have trim pots on the resistors to fine tune each set. You can get 1% resistors but 1% capacitors are quite expensive and hard to find. It is better to get capacitors with low temperature coefficients.

An alternate way would be to have a 378,000 oscillator and a number of frequency dividers. freq divder 500 756 450 840 400 945 350 1080 300 1260 250 1512 200 1890 150 2520 100 3780 50 7560

You could do the dividers with loadable decade counter ( 4 each ) and a set of PROM or PAL to decode the selects to the different divide numbers. All would be as accurate as the original 378000Hz oscillator. Dwight

Hi, I'm game, what is your application? What are you trying to achieve? If we know the full story we may be able to suggest a better solution.

Thanks.. Tom... :)