Hello,
I was reading an article ... or a blog or something about a student and his professor who designed a power supply that would over drive an LED with a .005 duty cycle ... it basically turned it on for .5 µs out of every 100µs which I initially thought there is no way they would get any light from it because that breaks out to like having the LED on for something like 5 seconds out of every 5 minutes I think ...
But I guess the point is when you want more light from an LED and you drive it hard for very short bursts of time, you can exceed their rated current levels without burning them out... so I decided to try this with those cheap 3.2 volt 150ma LEDs ... the ones where you can buy 100 of them for $7 on Amazon...
Anyway, I used a 540N MOSFET with an LED array that I already had soldered up to one of my project circuit boards which normally can run continuously with 19 volts on it, but I decided to crank up the power supply to 30 volts and pulse it with an Arduino.
The Arduino can't pulse faster than 1µs because the only command that I am aware of for fast pausing is the delayMicro command and you have to write directly to the register ports to skip all the wasted time when using the digitalWrite command...
So I initially set it up where it would pulse the LEDs for 1µs then 99µs off just to see if I would even get any light ... which surprisingly, I did though it was VERY faint and in a bright room would be almost unnoticeable ... so I cranked up my pulse times to 2µs then 3, etc till I was up to about 40µs on and 60µs off ... but this is where I get to my question...
As I began to decrease the frequency of my pulses, my bench power supply would just get louder and louder and I'm wondering if that means it's a crappy power supply or even if I'm potentially stressing it out too much or whats the deal with that? I've never heard it make any noise before really so it was kind of strange to hear it in the first place.
I was reading an article ... or a blog or something about a student and his professor who designed a power supply that would over drive an LED with a .005 duty cycle ... it basically turned it on for .5 µs out of every 100µs which I initially thought there is no way they would get any light from it because that breaks out to like having the LED on for something like 5 seconds out of every 5 minutes I think ...
But I guess the point is when you want more light from an LED and you drive it hard for very short bursts of time, you can exceed their rated current levels without burning them out... so I decided to try this with those cheap 3.2 volt 150ma LEDs ... the ones where you can buy 100 of them for $7 on Amazon...
Anyway, I used a 540N MOSFET with an LED array that I already had soldered up to one of my project circuit boards which normally can run continuously with 19 volts on it, but I decided to crank up the power supply to 30 volts and pulse it with an Arduino.
The Arduino can't pulse faster than 1µs because the only command that I am aware of for fast pausing is the delayMicro command and you have to write directly to the register ports to skip all the wasted time when using the digitalWrite command...
So I initially set it up where it would pulse the LEDs for 1µs then 99µs off just to see if I would even get any light ... which surprisingly, I did though it was VERY faint and in a bright room would be almost unnoticeable ... so I cranked up my pulse times to 2µs then 3, etc till I was up to about 40µs on and 60µs off ... but this is where I get to my question...
As I began to decrease the frequency of my pulses, my bench power supply would just get louder and louder and I'm wondering if that means it's a crappy power supply or even if I'm potentially stressing it out too much or whats the deal with that? I've never heard it make any noise before really so it was kind of strange to hear it in the first place.
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