Zener kinda turns on

First tell me what practical use this fake circuit requirement has.

s see some numbers.

a little

If it were a BJT, the +12V LED wouldn't ever turn off.

--
Cheers, 
James Arthur

On 4/19/2013 12:00 PM, John Larkin wrote:

little

Here is my (admittedly not terribly inspired) contribution:

Version 4 SHEET 1 880 680 WIRE -144 -64 -352 -64 WIRE 192 -64 -144 -64 WIRE 320 -64 192 -64 WIRE -144 -16 -144 -64 WIRE 192 48 192 16 WIRE -144 112 -144 64 WIRE 192 112 16 112 WIRE -352 144 -352 -64 WIRE 16 144 16 112 WIRE 320 144 320 -64 WIRE -144 224 -144 176 WIRE 192 224 192 112 WIRE 16 256 16 224 WIRE 16 256 -112 256 WIRE 320 256 320 224 WIRE 320 256 224 256 WIRE 16 272 16 256 WIRE 320 288 320 256 WIRE -352 384 -352 224 WIRE -144 384 -144 288 WIRE 16 384 16 352 WIRE 192 384 192 288 WIRE 320 384 320 368 FLAG -144 384 0 FLAG 16 384 0 FLAG 192 384 0 FLAG 320 384 0 FLAG -352 384 0 SYMBOL tl431 208 224 M0 SYMATTR InstName U1 SYMBOL tl431 -128 224 M0 SYMATTR InstName U2 SYMBOL res 0 256 R0 SYMATTR InstName R1 SYMATTR Value 5.1k SYMBOL res 0 128 R0 SYMATTR InstName R2 SYMATTR Value 4.7k SYMBOL LED -160 112 R0 WINDOW 3 -145 30 Left 2 SYMATTR InstName D1 SYMATTR Value NSPW500BS SYMATTR Description Diode SYMATTR Type diode SYMBOL res 176 -80 R0 SYMATTR InstName R4 SYMATTR Value 220 SYMBOL LED 176 48 R0 WINDOW 3 -145 30 Left 2 SYMATTR InstName D2 SYMATTR Value NSPW500BS SYMATTR Description Diode SYMATTR Type diode SYMBOL res 304 128 R0 SYMATTR InstName R5 SYMATTR Value 4.7k SYMBOL res 304 272 R0 SYMATTR InstName R6 SYMATTR Value 1.3k SYMBOL voltage -352 128 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL res -160 -32 R0 SYMATTR InstName R3 SYMATTR Value 220 TEXT -402 424 Left 2 !.tran 0.1 TEXT -408 448 Left 2 !.inc TL431.mo

see some numbers.

little

It might not turn off anyway, given Vgs(abs max) is 8V.

I kinda like Jan's idea, here is an "over easy" mod of it.

Did you expect better ?:-} ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

see some numbers.

little

I've tested a number of mosfets for actual gate breakdown. They all seem to die in the ballpark of 75 volts.

That is nice, quantitative and energy efficient. Something could be done with resistor packs, too.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

jlarkin at highlandtechnology dot com

Different color LEDs have different voltages. So the one with the transistor in line will operate a lower voltage led, this will then remove forward current from the higher voltage LED..

THat is the way I see it, could be doing something different, who knows.

Also, if you put a diode in series with one LED, and then T-bone that node to another LED and then to a switch (transistor for example), that switch should cause a voltage drop to where the in series diode LED node will lose the required voltage..

Just a thought.. Jamie

A) What's wrong with it?

B) Where is your, better circuit?

--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

It has four parts against your insane 19. It's energy efficient, in that there's no wasted LED current shunted to ground, and only a small V+ sense current. Total cost is about 5 cents plus the LEDs; how much does your circuit cost?

The worst thing about this circuit is the lack of independent LED brightness control, but that could be finessed. But it's just another topology toy.

You don't like it because I designed it and you don't understand it.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

Weaseling! Stalling!

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

t's see some numbers.

th a little

Ahh thanks, There's no-way I'm playing crossword puzzle component design with J.L. He'll kick my butt every time. I'm a 'class A' brute force kinda guy.

George H.

et's see some numbers.

ith a little

Nice, reminds me of a more spendy LED indicator circuit that I use for control loops, I drive two leds to show when the 'control parameter' is above or below the set point. Both turn off at 'zero' error.

George H.

Only downside is deadband between 8V and 9V, where neither LED lights.

This simulation shows (Monte-Carlo'd for 5% tolerance zeners and 1% resistors):

Version 4 SHEET 1 880 704 WIRE -384 48 -672 48 WIRE -96 48 -384 48 WIRE 112 48 -16 48 WIRE 304 48 112 48 WIRE -384 128 -384 48 WIRE 112 208 112 48 WIRE 304 256 304 48 WIRE -672 288 -672 48 WIRE -384 288 -384 192 WIRE -64 288 -384 288 WIRE 64 288 -64 288 WIRE -384 352 -384 288 WIRE -64 400 -64 288 WIRE -384 464 -384 432 WIRE -672 624 -672 368 WIRE -384 624 -384 528 WIRE -384 624 -672 624 WIRE -192 624 -384 624 WIRE -64 624 -64 480 WIRE -64 624 -192 624 WIRE 112 624 112 304 WIRE 112 624 -64 624 WIRE 304 624 304 320 WIRE 304 624 112 624 WIRE -192 688 -192 624 FLAG -192 688 0 SYMBOL LED 288 256 R0 SYMATTR InstName D1 SYMATTR Value NSPW500BS SYMBOL nmos 64 208 R0 SYMATTR InstName M1 SYMATTR Value AO6408 SYMBOL res 0 32 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value {mc,2.2k,tolR} SYMBOL res -80 384 R0 SYMATTR InstName R2 SYMATTR Value {mc,10k,tolR} SYMBOL LED -400 464 R0 SYMATTR InstName D3 SYMATTR Value NSPW500BS SYMBOL res -400 336 R0 SYMATTR InstName R4 SYMATTR Value {mc,1.2k,tolR} SYMBOL zener -368 192 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D4 SYMATTR Value BZX84C7V5 SYMBOL voltage -672 272 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 5 TEXT -440 656 Left 2 !.dc V1 0 12 10m TEXT 352 392 Left 2 !.MODEL BZX84C12V D\n+ IS=2.6665E-18\n+ N=.82284\n+ RS=.51617\n+ IKF=11.760E-3\n+ CJO=48.079E-12\n+ M=.32805\n+ VJ=.62172\n+ ISR=47.692E-12\n+ BV={mc,12.119,tolZ}\n+ IBV=.54544\n+ TT=825.22E-9 TEXT 352 40 Left 2 !.MODEL BZX84C7V5 D\n+ IS=2.6665E-18\n+ N=.82284\n+ RS=.51617\n+ IKF=11.760E-3\n+ CJO=63.513E-12\n+ M=.33559\n+ VJ=.66795\n+ ISR=1.1222E-9\n+ BV={mc,7.6329,tolZ}\n+ IBV=.94329\n+ TT=2.7411E-6 TEXT -24 656 Left 2 !.param tolZ=.05 ; +/- 5% zener tolerance TEXT -24 688 Left 2 !.step param X 0 20 1 ;dummy TEXT -24 672 Left 2 !.param tolR=.01 ;resistor tolerance TEXT -256 8 Left 2 ;plot I(D1), I(D3)

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)

Full listing at... Message-Id:

Sorry! Looks like a sloppy solution :-( ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Not my solution, just an MC analysis of Fred Bartoli's solution.

Not as elegant, or precise as yours, but cheap.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)

Trannies and resistors are cheap-cheap. LM317? TL431? Can't be very much. And then days of tweaking to make cheap-cheap-cheap actually work >:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

My 2 cents:

_ PAGE1.pdf

Regards

Klaus

Version that turns 5V LED off when 12V LED turns on with sufficient current:

_ PAGE1.pdf

Cheers

Klaus

be

Both in same PDF file with no spaces :-)

Cheers

Klaus