I want to make 2 sets of 3 led’s flash like this Does any one have any ideas? I want them to run on 5 volts Each led is 25 milliamps at 3.5 volts.
I think I got how this'll work. First, you setup a 555 timer in astable mode, set to a frequency of 1/2 of the desired duration between pulses. This will feed into a 4017 decade counter. The outputs will be connected in this manner: 0,2,4 as one group, 5,7,9 as another. Since I doubt that this IC is capable of outputting 20mA of current, you'll need to find the appropriate transitor to drive the LEDs. Wish I could help you there, but that's one subject of electronics where I'm utterly clueless. From what I've seen, there's two types of 4017 counters, by Fairchild and Phillips. Phillips has two clock inputs, one of which is negative edge triggered, the other positive edge triggered. Since our clock is continuously running, it shouldn't matter which one you connect it to. Besides that, the only thing left to connect is output 9 (that is, the 10th output) to reset.
Picture Couple things to note: A. The supply voltage is 5v B. I purposely left out the values for the resisitor, potentiometer, and capacitor since you need to define them. Use this site for help C. You might need a resistor on the base of the transitor. D. Those are NPN transistors, as the outputs are active high (positive) E. The 4017 counter will have Vcc and Ground inputs, but TINA left them off for some reason, otherwise they'd be connected. In case your unclear, the flasher works by having only every other pulse (except for when the groups change) connect to the LEDs, so it goes On-off-on-off-on-(group 2)-on-off-on-off-on-(group 1)-so and so forth.
Thanks but thats all foren to me i dont know a great deal about electronics but i might be able to get some one who does know a bit more than me to look at your info thanks anyway.
Another possibility is the 4060b, which has a built-in oscillator so saving a 555 chip. Putting a led between different divider outputs gives a wide range of flash effects, simplest being a double-flash like but you can certainly get 4 flashes with a pause between. Speed easy to alter. Again you'll need a transistor to boost current for several leds on together. More details here.
this is a good circuit however as outputs 5,7 and 9 are connected, as soon as 5 is on it will re-set the circuit. avoid this by placing a diode on output 9 to stop the voltage from the other outputs resetting the circuit. i also think connecting them all together straight off might be wrong, however i'm not sure, but i allways thought that if a pin outputs and the voltage goes back IN another pin it might fry the IC. problem solved by protecting each pin with a diode. can someone please confirm this, or just tell me to FCUK off... either way, hope i helped. Snood
Bleh, thanks for catching that Snood, I didn't even think about that. Even if connecting each of the outputs is bad, this can be remedied by connecting them to OR gates. If you were to use gates, you could also remedy that problem I screwed up by using an AND gate, inputs being the output of the OR gate for the 2nd group and the output of pin 9, the output of which would go to the reset pin. I know that sounds cryptic, but I'm not at my computer w/ the electronics software I use.
why bother using more ICs and slightly more complex (not challenging i know) but i'm sure 6 good ole diodes will do the trick. Snood
you also need a resistor on each transistor (base) or else they will fry ... the can only stand 0,6-0,7 volts...
this will work fine - Edit: you might also meed a current limiting resistor. as the same ammount of led's are on at any one time, you just need a single common resistor connecter to the cathodes. Snood
I updated that schem I made to fix the thing Snood caught and something else I did to: I tried to turn an NPN transistor into a PPP transistor.
