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Re: Simple inverter switch transistor circuit help needed

This will work most of the time. It depends on the power supply voltage

>and LED forward voltage drop: > > View in a fixed-width font such as Courier. > > . > . > . / > . Vcc>----+----o o----+---> > . | SW | SW closed > . [R1] | > . | | V -V > . | | F EB > . + - - ------ | * > . V V D1 V D2 R1 \\ * > . F - - |\\ * > . - | | | \\ * > . | | | \\ * > . >| | | \\ * > . |---------+ I ^ | \\ * > . /| | d | | \\ * > . | [R2] | \\ * > . | | +*-*-*-*+*----+-- > . | | V -V V > . --- --- F EB F > . V -> > . d > . > . > .
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This will work _all_ the time:

. 
.Vcc>--+----------------+
.      |                |
.    | O                |
.    |                 [R3]
.    | O                |
.      |                |
.      |A         +-----+
.    [LED1]       |     |
.      |          C     |A
.      +--[R2]--B NPN [LED2]
.      |       Q1 E     |
.     [R1]        |     |
.      |          |     |
.GND>--+----------+-----+
.
Reply to
John Fields
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P.S.

Version 4
SHEET 1 880 680
WIRE -160 96 -432 96
WIRE 80 96 -160 96
WIRE -160 128 -160 96
WIRE -208 144 -336 144
WIRE 80 144 80 96
WIRE -208 192 -240 192
WIRE -160 240 -160 208
WIRE 80 256 80 224
WIRE 176 256 80 256
WIRE -432 288 -432 96
WIRE -336 288 -336 144
WIRE 80 304 80 256
WIRE 176 320 176 256
WIRE -160 352 -160 304
WIRE -96 352 -160 352
WIRE 16 352 -16 352
WIRE -160 384 -160 352
WIRE -432 512 -432 368
WIRE -336 512 -336 368
WIRE -336 512 -432 512
WIRE -240 512 -240 192
WIRE -240 512 -336 512
WIRE -160 512 -160 464
WIRE -160 512 -240 512
WIRE 80 512 80 400
WIRE 80 512 -160 512
WIRE 176 512 176 384
WIRE 176 512 80 512
WIRE -432 592 -432 512
FLAG -432 592 0
SYMBOL res 64 128 R0
SYMATTR InstName R1
SYMATTR Value 150
SYMBOL npn 16 304 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL LED 160 320 R0
SYMATTR InstName D1
SYMATTR Value QTLP690C
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 0 336 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 2000
SYMBOL voltage -432 272 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage -336 272 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 24 104 Invisible 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 1e-6 1e-6 1 2)
SYMBOL sw -160 224 M180
WINDOW 0 32 15 Left 0
WINDOW 3 32 44 Left 0
SYMATTR InstName S1
SYMBOL res -176 368 R0
SYMATTR InstName R3
SYMATTR Value 150
SYMBOL LED -176 240 R0
WINDOW 3 87 38 Left 0
SYMATTR InstName D2
SYMATTR Value QTLP690C
SYMATTR Description Diode
SYMATTR Type diode
TEXT -408 536 Left 0 !.model SW SW(Ron=1 Roff=10Meg Vt=0.5Vh=0)
TEXT -408 568 Left 0 !.tran 0 10 0
Reply to
John Fields

Just for grins, I ran that circuit through my LTSpice-to-ASC converter and got this:

Jon

Reply to
Jonathan Kirwan 

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WOW!

Pretty damn slick!!! :-)
Reply to
John Fields

This one is better'n the both of them, your circuit wastes current:

Why don't you verify the equations ( I whipped them out) and construct a design note on how to select R1,2,3 in terms of Vcc, and VF1,2...

View in a fixed-width font such as Courier.

. . . / . Vcc>----+----o o-----+--->

. | SW | . [R1] | . | | Vcc-V -V . | | F1 EB R2+R3 . + - 1N4148| R1 = ----------- - ----- . V V D1 .--|| | | . |--+-[R3]--+ Vcc-V . /| | F2 . | [R2] R2 = --------------- . | | V -0.7 . | | F2 . --- --- I + ------- . F2 R3 .

Reply to
Fred Bloggs

hehe. If you are interested, I can provide a link where you can download it -- with or without source. Like anything done for free, it has its limitations (due to my time.) But I wouldn't mind feedback about what to work on. A little useful focus wuold sharpen the use of what time I can afford to enhance it.

The program is something I whipped up a while back when I decided I thought I'd let LTSpice capture the schematics I post in ASCII. It turned out to actually be easier than I first imagined, but there were a few things I had to learn along the way. Parsing was easy. The key was to imagine an ASCII drawing space and to use "greatest common divisor" means to find the least number of ASCII characters required to replace wires and so on.

Jon

Reply to
Jonathan Kirwan 

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Good circuit, but I think I\'ll forego the analysis and tutorial
writing.  Sounds too much like work that ought to be coming out of
_your_ camp. ;)
Reply to
John Fields

It runs under DOS, for now. Written in C. I'll fire up a VB for Windows version, if you prefer that. Shouldn't take too long to do that. Current link is at:

formatting link

Jon

Reply to
Jonathan Kirwan

Thanks! Do a VB version if you want to, but C is fine for here. :-)

Thanks! Rich

Reply to
Rich Grise

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