driving an LED with a 7406 question

On Tue, 13 Feb 2007 17:12:11 GMT, Rich Grise wrote:

--- Um, It's TTL, not CMOS. The pullup isn't a BFD.

Here's a 7406, run it and watch what happens to the output when the input floats:

Version 4 SHEET 1 880 680 WIRE -48 48 -464 48 WIRE 256 48 -48 48 WIRE 400 48 256 48 WIRE 512 48 400 48 WIRE -48 80 -48 48 WIRE 256 80 256 48 WIRE 400 112 400 48 WIRE 512 112 512 48 WIRE -48 192 -48 160 WIRE 160 208 128 208 WIRE 256 208 256 160 WIRE 256 208 224 208 WIRE 512 208 512 192 WIRE 592 208 512 208 WIRE 512 224 512 208 WIRE -128 256 -208 256 WIRE -96 256 -128 256 WIRE 64 256 0 256 WIRE 256 256 256 208 WIRE 400 272 400 192 WIRE 448 272 400 272 WIRE 400 304 400 272 WIRE 128 336 128 304 WIRE 256 352 256 336 WIRE 336 352 256 352 WIRE -128 384 -128 256 WIRE 256 384 256 352 WIRE -464 400 -464 48 WIRE 128 432 128 416 WIRE 192 432 128 432 WIRE 128 448 128 432 WIRE -464 560 -464 480 WIRE -128 560 -128 448 WIRE -128 560 -464 560 WIRE 128 560 128 528 WIRE 128 560 -128 560 WIRE 256 560 256 480 WIRE 256 560 128 560 WIRE 400 560 400 400 WIRE 400 560 256 560 WIRE 512 560 512 320 WIRE 512 560 400 560 WIRE -464 592 -464 560 FLAG -464 592 0 SYMBOL res -64 64 R0 SYMATTR InstName R1 SYMATTR Value 6k SYMBOL npn 0 192 R90 WINDOW 0 58 34 Left 0 SYMATTR InstName Q1 SYMATTR Value 2N2222 SYMBOL diode -112 448 R180 WINDOW 0 51 30 Left 0 WINDOW 3 24 0 Left 0 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL npn 64 208 R0 SYMATTR InstName Q2 SYMATTR Value 2N2222 SYMBOL res 112 320 R0 WINDOW 0 -39 44 Left 0 WINDOW 3 -46 76 Left 0 SYMATTR InstName R2 SYMATTR Value 100 SYMBOL res 112 432 R0 WINDOW 0 -47 37 Left 0 WINDOW 3 -60 68 Left 0 SYMATTR InstName R3 SYMATTR Value 1000 SYMBOL npn 192 384 R0 SYMATTR InstName Q3 SYMATTR Value 2N2222 SYMBOL diode 224 192 R90 WINDOW 0 -36 36 VBottom 0 WINDOW 3 -32 36 VTop 0 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL res 240 64 R0 SYMATTR InstName R4 SYMATTR Value 1.4k SYMBOL res 240 240 R0 SYMATTR InstName R5 SYMATTR Value 2k SYMBOL npn 336 304 R0 SYMATTR InstName Q4 SYMATTR Value 2N2222 SYMBOL res 384 96 R0 SYMATTR InstName R6 SYMATTR Value 1.6k SYMBOL npn 448 224 R0 SYMATTR InstName Q5 SYMATTR Value 2N2222 SYMBOL voltage -464 384 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL res 496 96 R0 SYMATTR InstName R7 SYMATTR Value 1,6k TEXT -450 576 Left 0 !.tran .1 uic TEXT -208 288 Left 0 ;IN TEXT 552 232 Left 0 ;OUT

-- JF

you

Probably not, it's just that I'm chicken to let inputs float at all. :-)

Thanks! Rich

...snip...

Well, let's see... rude, obnoxious and ignorant. What a great combination!!!

Dude, chill out a little bit. Simulations are not the real world and unless you are dealing with no-neck, leather clad bikers with chains and drawn knives, you are better off not trying your very best to PO everyone you speak too. BTW, I know this from experience. :^)

Huh? He was a little bit, um, abrupt, but I don't find his post "rude, obnoxious and ignorant" at all. :-)

Cheers! Rich

PLONK.

thank you

I'm sure it's working. It's just that he doesn't understand how it works.

Graham

Mr Calm and Collected speaks again !

Graham

thank you

You're rarely calm and collected.

You're usually profane.

Graham

Says it all really.

Boy, now I know why they came up with LOL! When I read this everyone around me turned to see what I was laughing about!!!

It's not that you "can't", it's just that calm collectedness is very seldom associated with profanity. ;-)

Thanks, Rich