555 blinking unit

[wee wee]

Hi Everyone,

Sorry for the basic question...

So I need to built a beacon light with LEDs. for the flashing unit I would like to use the 555 ic. But since I am not too good I just went to the electronic shop and asked :" I need to make a led blink, one sec on one sec off, please give me what i need for it i will then go use Google image to find the right scheme".

.... now at home I am sitting with component that differ from everything i find on the Internet... maybe the vendor got confused.

So here is what I have?

1x 555 ic
1x MOSFET
1x capacitor 100 uf 1/4
1x capacitor (witch only writing on it is "103" not even sure where the + side is...)


So how do i connect those to make my led blink???

Ready , set .... GO!!!! :p

[stj]

Re: 555 blinking unit

example circuits are in the datasheet.

[wee wee]

Re: 555 blinking unit

Hi STJ,

Thanks for the quick reply,

Can't find what I am looking for in that pdf, because I am not good enough I get confused everywhere.

Can I even achieve my goal with those only component I got ?

[stj]

Re: 555 blinking unit

no.
you need some resistors atleast to set the speed of the 555.

[budm]

Re: 555 blinking unit

Just do the search 'FLASHING LED USING 555' you will see lots of circuits.
I.E.:
http://rookieelectronics.com/555-tim...-flashing-led/

http://www.ohmslawcalculator.com/555_astable.php

http://www.bowdenshobbycircuits.info/555.htm

[wee wee]

Re: 555 blinking unit

hi guys,

Thx budm thanks for the nice links,

I have tried to build this circuit;

http://1.bp.blogspot.com/-CNBgqyD0uM...1600/555-1.png

But it didn't work, I must have made a mistake somewhere...
So went to do a simpler one:

http://images.brighthub.com/f1/4/f14...022f8_orig.jpg

The light comes on onces then off and thats it .... only one blink
Tried again with this one

http://www.ohmslawcalculator.com/555_astable.php
Then same, only one blink

I have used a 12v led... and put 10v input

Still don't get what to do with the mosfet...

[Andrew F. Ali]

Re: 555 blinking unit

Pin 3 out from the 555 IC will go to the Gate on the Mosfet while the +12V will connect in series with a bulb while the Source will go to Gnd. Therefore, the Mosfet will act like switch........

[wee wee]

Re: 555 blinking unit

I will try that thanks,

But most of the circuit I found don't have the mosfet so why would mine do that?

[budm]

Re: 555 blinking unit

The 555 does not have high current drive, so you need transistor, MOSFET to source or sink the high current, or use relay.
If you are going to drive the lamp, the cold resistance can be 10 times lower than the HOT resistance so the current in rush will be very high.

[budm]

Re: 555 blinking unit

http://www.williamson-labs.com/555_apps.htm

[wee wee]

Re: 555 blinking unit

Ok got it right with two transistor and a relay it works like a charm.

But now for an other project I need an LED dimmer. look like its gotta work with a 555 too.

I have built this two:
http://rcexplorer.se/diy/2010/02/led-photobuild-lights/
http://www.talkingelectronics.com/pr...LED-Dimmer.gif

But the led is blinking ??? after getting through all that trouble to get one to blink ....
I don't want it the blink just want to be able to dim it.

What did i got wrong in those circuit?

[eccerr0r]

Re: 555 blinking unit

Probably your capacitor is too big. The timing capacitor you have from pin 2 to GND needs to be 100 nanofarads and not something like 100 microfarads.

[stj]

Re: 555 blinking unit

that dimmer works by blinking the led very fast.
what are you actually making and why?
because there are other ways of dimming an led.

[wee wee]

Re: 555 blinking unit

What are those other way to dim a led??

Basically I have a three way switch that light up 3 red led on one side or two white leds in the other position. I want to put a potentiometer at the entry of that switch to dim the leds selected (either the white or the red one).

The two groups of led (3v) are in parallel with the adequate resistor (12v input) .

Can I get that right with just a potentiometer ?? a 10k?

Thanks

[wee wee]

Re: 555 blinking unit

anyone ...

[stj]

Re: 555 blinking unit

led dimming is best done with a current regulator circuit.
pwm is not for beginners really.
*i* would use a pic microcontroller, but i can write the software for it and program it!