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an electric device that gives electric pulses

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wado

New Member
Hi I’m not good at electronic and I have this small project.
I need to build a circuit that can give electric pulses using timers
I have LM 555cn timer
two resistor R1=180 kΩ R2=1 kΩ
tow capacitor C1=4.7µF C2=0.01µF
one LED
is this is the right components and how to connect them
thank you
 

MikeMl

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Most Helpful Member
Google is your friend. You will need a resistor (~470Ω) in series with the LED to limit its current so you dont damage it. The referenced circuit shows two LEDs; you only need one; either between V+ and pin3 or between pin 3 and ground.
 

wuchy143

Member
Also if you use the 555 and read up on Vcontrol for it you can adjust the duration of the pulses. If I'm not mistaken doing this will be able to vary the intensity of the LED.(basically PWM) I forget exactly how it's done but by varying Vcontrol you change the comparitors inside the 555 which changes the duration of you pules set by the cap and two R's.
 

MikeMl

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Most Helpful Member
It would take a second 555 to modulate the brightness that way. If the OP really wants to vary the brightness of his LED, why not just put a rehostat in series with the LED inplace of the fixed resistor:D
 

wuchy143

Member
agreed. That's probably the simplest way. :) Why would you need two 555's though? Don't mean to get off subject...just curious
 

MikeMl

Well-Known Member
Most Helpful Member
agreed. That's probably the simplest way. :) Why would you need two 555's though? Don't mean to get off subject...just curious
One to set the flash rate of about 2 flashes per second, and the second to PWM the LED at a rate of 30-60 Hz(above the eye's flicker fusion rate).
 
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Boncuk

New Member
agreed. That's probably the simplest way. :) Why would you need two 555's though? Don't mean to get off subject...just curious
one to generate pulses and the other one to vary the duty cycle.
 
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