Hi there!
While going through my electronics cupboard, I came across a transformer rated at 32volts/ 3.22Amp (105VA). I would like to build a variable power supply with a current limiting feature using this transformer. Unfortunately, all the regulators I came across, has a maximum input...
Hi guys! I tried a new LED, its a L53LSRD made by KingBright. These babies are so cool, 8 mcd at only 2mA. They go all the way up to 30mA and the view angle is a whopping 60 degrees.
I was about to scrap the multiplexing idea and drive the LEDs on all the time, but the new LEDs have solved my...
I have made an amazing discovery thats gonna change the electronics industry forever. He he he ! I finally understand what you guys have been telling me over the past week. Myndex, i read over your first post carefully, all the answers are there.
Firstly, if i had 10 LEDs in series, that would...
Well, i pulled out one leg of the resistor and connected my ammeter in series. I measured the volt drop Of each LED, it 1.71V. Its not the high bright type, normal GaAs- model BL-B5134 bright red. I want to get 60mA through them when connected directly. So that when i multiplex them by 6, the...
Hi there! i have a quick question. I connected 12 red LED's in series with a 100 ohm resistor to a 30V supply, no transistors. Its looks really bright. But according to my calculations, 30v - (12*1.7) = 20.4V. therefore 30v -20.4v=9.6V. 9.6v/100ohm= 0.096A. Thats the current that should flow...
GUESS WHAT ??? Its working ! When those LEDs illuminated, I couldn't stop smiling. You guys are my mentors, thanks.
I swapped the NPN's and PNP's around. I added BC 547's from the 74HC238 to drive the bases of the PNP's. I've only used about 15 LEDs so far cause my power supply goes up to 30V...
Ok guys, I took your advice. I brought some new transistors, BD 679 to drive the LEDs anode and BD678 to drive the cathode. They can handle up to 4A with a gain of 750. I'm using a 1K resistor on the their bases. This should fully saturate them. A 10 ohm resistor limits current to about 0.5A...
I'm building a digital clock using LED's in a 7 segment pattern. Each segment has around 35 LEDs and the height of a complete display is around 12 inches. i'm using two displays each, for hours, minutes and seconds. A PIC 16f877 sets the number to be displayed and a 74HC238 demultiplexer selects...
