Home     Contact     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS     Terms of services     Privacy policy  
   
 Home     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science   

Author Topic: help with my led project - first post  (Read 3683 times)

0 Members and 1 Guest are viewing this topic.

dixy

  • Guest
help with my led project - first post
« on: December 15, 2010, 16:06:57 PM »
hi everyone, its my first post on this forum, i have been reading alot of the information on this website and i find it very useful and  have learned alot.

the project i have in mind is to redo my cars speedometer and other dashboard switches, what i want is to have the leds to fade on when switched on and fade out when switched off.

from what i have read so far i have to use a pwm circuit, however i might be wrong as all i have found is circuits which allow you dim the leds which is useful but not what i am looking for.

to make them fade of i would imagine that we would have to add a capacitator or some other component to store a charge and gradually decrease to supply voltage when the signal voltage is removed.

the circuit will be running a maximum of 20 leds,

it the first time i have made, or will be making a pcb out of school (i studied engineering, but i didnt pay attention)

any help would be greatly appreciated.

ps. if i have posted this in the wrong section please move it to the correct place.

thank you

dixy

  • Guest
Re: help with my led project - first post
« Reply #1 on: December 16, 2010, 19:03:31 PM »
anyone?

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: help with my led project - first post
« Reply #2 on: December 16, 2010, 19:15:32 PM »
i am working on one very similar circuit. i use analog electronics and no PWM, to keep it simple. i have a slight problem. if the capacitor is for any reason completely discharged (eg if the circuit is off for a while), then upon power on i get a delay of about 1 to 2 seconds before the LEDs starts turning on.  Otherwise it works ok (dim on - dim off)
Patience. I will find a way.

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: help with my led project - first post
« Reply #3 on: December 17, 2010, 09:08:12 AM »
So, i solved the problem with 2 transistors (instead of 1). I could not keep it more simple, because it would be a headache to set the times and the standby brightness. I will post it today afternoon or within the next 1-2 days (whenever i have some time). I will publish it in the RSS so take a regularly look.

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: help with my led project - first post
« Reply #4 on: December 19, 2010, 13:48:35 PM »
Here you are:

LED Fade-In Fade-Out Dimmer

I will upload also video with this, today or tomorrow. enjoy.

endorser

  • Guest
Re: help with my led project - first post
« Reply #5 on: May 05, 2011, 10:11:49 AM »