555 PWM Question

Thread Starter

malkos

Joined Apr 14, 2010
2
I'm just starting on learning electronics, and made a 555 astable oscillator/pwm based off
h**p://www.sentex.ca/~mec1995/circ/pwm555.html
Rather than the transistor, motor R2 and Schottky diode i have 2 leds hooked up. One from V+ to pin 3, and one from pin 3 to ground. This flashes them alternately. But the led sourced from pin 3 fades up, rather than blinking on...
The only other change from the above circuit is a 10μf cap for C1, to adjust the frequency.
Basically, how can i get the second led to turn on sharply, rather than fade up?
Thanks for any tips...
 
I'm just starting on learning electronics, and made a 555 astable oscillator/pwm based off
h**p://www.sentex.ca/~mec1995/circ/pwm555.html
Rather than the transistor, motor R2 and Schottky diode i have 2 leds hooked up. One from V+ to pin 3, and one from pin 3 to ground. This flashes them alternately. But the led sourced from pin 3 fades up, rather than blinking on...
The only other change from the above circuit is a 10μf cap for C1, to adjust the frequency.
Basically, how can i get the second led to turn on sharply, rather than fade up?
Thanks for any tips...
put a capacitor of 47uf 16 volts across +ve and Negative cell terminals. did you get what u want?
if yes then every circuit of 555 needs this when you make use of both +ve and -ve from the outpin 3.
 

Thread Starter

malkos

Joined Apr 14, 2010
2
Thanks for the tips folks. Got it all working as expected. it is a standard ne555, i just think i had something wrong on my breadboard. i don't have an oscilloscope, but it seems the way i had it put together was making a sawtooth, rather than square wave. After rebuilding the circuit a few times it seems to be behaving its self.
-Malkos
 
Top