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Test Results of the Basic NPN LED flasher.

A While ago I posted a circuit, something like this.

1000 ___ 12V+ -|___|-+--+----------+ | | | | | | | | | | | | NPN | LED - | | === GND (created by AACircuit v1.28.6 beta 04/19/05
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And asked about its longevity of the NPN transistor used this way?

Of course, it turned into a three ring circus, so for the last week or so, I have been operating one using a bench supply and it seems to work just fine.

I didn't do a beta test on the transistor to see if it lost anything but I really don't care because this is going to be a permanent use of a transistors life.

Also, with experimentation I was able to come up with various configurations that was stable across a wide range of voltages starting at 11 Volts and up. These make for cheap throw away things.

Jamie

Reply to
Jamie
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I like it! I think I'll try the circuit tonight and see how it works with a coin cell, a white LED, and my "1 transistor flyback converter" circuit.

Reply to
Bitrex

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Reply to
George Herold

No. The reason it works is the fold-back characteristic of the LVceo breakdown of a transistor. In this case the emitter actually functions as "collector" and vice versa, giving a lower threshold.

Simulation doesn't work because the BJT model doesn't include this effect.

...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     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.
Reply to
Jim Thompson

[snip]

I have determined that the "Mextram" model covers BVceo/LVceo effects. PSpice has this in their "Level=2" model. I don't know if LTspice has this or not. Of course good luck at finding a manufacturer that includes these parameters ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     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.
Reply to
Jim Thompson

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