Question to people about a circuit

Post Reply New Topic

Hi, I used this circuit below to make a led flasher, works great but I'd like to know if
there's a way to re-use it but instead of the two LEDs flashing, to dim.
That, or make the LEDs flash slower (like a LED stay on for 2 secs, then the other, etc.).

thanks

To slow the flashing down either use bigger capacitors or put resistors in series with the capacitors.

To dim you could use smaller capacitors that would make the LEDs flash so fast they would appear to be on steadily but at a lesser brightness. If you wanted one brighter than the other you could use capacitors that have higher or lower capacitances within the same order of magnitude.

put the electrolytic capacitors in backward, trust me it is a lot of fun

wait a minute i am sure that is the same kit i leaned to solder with

I'm too dumb to understand what you want to do or how to do it if I understood.
Microcontrollers make having to know how to do what you ask alot easier

Anyway that circuit looks like an Astable Multivibrator circuit. So do what Ahayes said I guess and use the math on the link below to get the values you need.

http://en.wikipedia.org/wiki/Multivibrator

frequency = 1 / 0.693(R2C1 + R3C2)

2 seconds (your goal ?) (.693)(R2C1 + R3C2) = 1

1/ (2 *0.693) =R2C1 + R3C2

lets R2 = R3 and rename to R
let C1 = C2 and rename to C and it equals 0.00001 F (what your circuit has)

1/ (2 * 0.693) = R (0.00002)
R = 36075 ohms

Since R2 and R3 are 10K and you have a variable resistor in the circuit merely adjusting the screw on the variable resistors (RV1 and RV2)should allow the 2 second delay you wish.

Can not be that simple so I guess you want the led to stay on longer. An electrolytic capactor could be added to feed to both leds then the circuit set very slow with a high R
value. So say the circuit every 10 seconds would charge up the capacitors then they would slowly discharge lighting the leds. So maybe the + end of the capacitor would be
connected to the 1 k-ohm input resitor on the led (end the farthest away from the LED!)
and the negative end of the capactor hooked to ground.

Hi, thanks ahayes
gilb: I won't follow your "fun" advice
Machine: thanks for the info man, I'll see if it works

awww you're no fun
at least these people would do it (it is the only fun way to learn electronics)
[youtube]http://www.youtube.com/watch?v=NvwMt5C0ED0[/youtube]

Also replace the resistors with wires. Or even better -a lot of 1 ohm carbon film resistors in parallel. They make the most smoke. They'll also detonate the caps faster! And take a deep breath and watch the destruction. You'll be getting the most out of an overpriced kit(Almost all kits are overpriced).

I wouldn't know much about that circuit so can't help you there, but for all those intent on destroying electrolytic capacitors then just run a too-higher voltage through them, blows them apart, I ran 12 volts (by accident) through a portable multiband reciever, it blew up a 220µF electrolytic capacitor rated at 10 volts on the input stage for the power adaptor connection, though thankfully the reciever still runs off batteries, just need to replace the capacitor

and yes there was a loud bang and smoke involved, heh

I heard a quote from a guy his professor told him all diodes will function as light emitting
diodes at least one time

hehe. Saxen told me about what happens to capacitors used wrong, if I didn't knew that, I'd have followed your advice

%53%61%78%6f%6e%20%69%73%20%61%20%73%70%6f%69%6c%20%73%70%6f%72%74
(only joking )