Flip flop LED circuit

This is a simple circuit based on transistor 2N 2222A and some resistors, there are 2 LED s and when one is on other will be off and this will be repeated in equal intervals of time  

Step 1: Parts list

2 x  2N2222 transistor

2 x 10k resistor (brown black orange)

2 x 390 ohm resistor( orange white brown)

2 x  100uf electrolytic capacitor

1 x blue LED (or other colors u like)

1 x red LED (or other colors u like)

battery ( 3 - 9v)
 
switch

Comments

[clayman987]

I replaced an led with a piezo buzzer and I used new batteries, and suddenly only the other led will turn on when its powered up. How can I change my circuit so the piezo and led blink opposite? It has worked a while ago but after recovering the project, with new batteries, it doesn't work. Help please,
Thanks,
Clayton

[PlutoniumPurushoth]

Can I use BC547 instead of 2N2222A ?

[clayman987]

I am wondering are the transistors 3904 or 2N2222A because all I have is 3904. And for the 390 ohm resistor can I use 330 ohms, sorry I don't have many parts!:)

[Mudbud]

Those should work, as long as its NPN, (to an extent)

[Derrick911]

I have a few questions;
1.) are the 10k resistors that are wired to the capacitors for discharging them?
2.) if using a 3 volt supply should i use a weaker resistor as opposed to the 390 ohm?
3.) how fast does your run, im looking for police light for an rc car fast

[sooraj619]

1) yep,
2) use a 10k variable resistor adjust its value for a 3v supply and reduce value of 390 ohm to lower values
3)you can use a 10k variable resistor in place of 10k resistor or change the capacitor value to change the flash rate

[jimmy558]

can i operate this with aproximately 7 volt battery??

[sooraj619]

yes

[jimmy558]

what is the timing of leds turning on & off...??

[sooraj619]

about 1 second, you can increase or decrease the fading effect by changing the values of both the capacitors

[kyooby]

thank you.i remember toose days when i maded this stuffs.cool

[sooraj619]

thanks

[therookie187]

maybe this is better

[sooraj619]

ok

[gzaloprgm]

Just one correction: It should be called Astable, not FlipFlop

[suckafish]

actually chief this is called a flipflop http://talkingelectronics.com/projects/5-Projects/Projects16.html

[magic monkey]

An astable multivibrator and a flip flop are basically the same type of circuit. However flip flops generally require an input or timer on a gate to make the state change whereas an astable multivibrator is not stable in either state and will constantly change between states without an input or timing circuit.

[MROHM]

magic monkey You are Correct!! Normally a Flip flop needs a clock pulse to change it's output Logic state 1 or 0. Where as an astable Multivibrator uses FEEDBACK to sustain oscillation( LED FLASHING)

[sooraj619]

ok

[David97]

We made this at school and made christmas lights. When we made it the curket dyagram was called a FlipFlop.

[chipper35]

Not bad at all! .....would've like to've maybe seen a few more steps/photos, though.

[sooraj619]

thanks

[ray_Bond]

good work sooraj bhai :)
keep it going
god bless you .

[sooraj619]

thanks a lot

[axeman911]

Good Job. Looks pretty cool!