can i use LED on collector? - Page 2 - Electronic Circuits Projects Diagrams Free

Mikebits · 6th July 2008, 10:21 PM

Quote:

Originally Posted by Nigel Goodwin

It's not a 'suggestion' it's a necessity

My point was, if the OP is going to ask for suggestions, then he should take them. I think it has been mentioned more than once that the transistor is not even needed, yet the transistor is still there and without the suggested base I limit.

Sceadwian · 6th July 2008, 10:49 PM

The transistor is needed if enough LEDS are used, his schematic shows 11 LEDS, unless they're multiplexed the pass transistors are required, with the HFE of most common transistors the current hardly needs to be even 1ma to saturate.

Mikebits · 7th July 2008, 02:57 AM

The PIC I/O pins are capable of delivering 25ma per pin. Since this is a dancing LED circuit, it is unlikely all led's will be lit at the same time for very long if ever. So it seems to me the transistors are not needed.

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6th July 2008, 10:49 PM	(permalink)
Sceadwian	The transistor is needed if enough LEDS are used, his schematic shows 11 LEDS, unless they're multiplexed the pass transistors are required, with the HFE of most common transistors the current hardly needs to be even 1ma to saturate. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

7th July 2008, 02:57 AM	(permalink)
Mikebits	The PIC I/O pins are capable of delivering 25ma per pin. Since this is a dancing LED circuit, it is unlikely all led's will be lit at the same time for very long if ever. So it seems to me the transistors are not needed.