BJT Toggle Switch Challenge

245

02:20:15

This is a challenge for creating a mechanism that toggles an LED every time an NO push button is pressed and released. The circuit must contain one DC voltage source, one LED that will be the output, one NO push button that will be the input, any number of BJTs (NPN and PNP), and any number of resistors (any value). Nothing else, like capacitors or relays. The number of points a circuit scores is the number of BJTs it contains. The circuit with the fewest points wins (like in golf, the person who scores the fewest points is the winner because they had to hit the ball the fewest times). This circuit scored 17 points. Can anyone get a better score than me?

Current winner: @hurz at 5 points. Link: http://everycircuit.com/circuit/5709202692767744

published 7 years ago

hurz

7 years ago

http://everycircuit.com/circuit/5709202692767744

hurz

7 years ago

BTW, your circuit scores 17, but i think you have something different as winning circuit in mind, lets see.

jason9

7 years ago

Oh, yeah I forgot about that last BJT for lighting the LED. I’ll fix the score.

jason9

7 years ago

Also, I don’t have anything better in mind than what’s already here.

592azy2circuitdude

7 years ago

Congrats @hurz, that circuit is awesome!

hurz

7 years ago

Thank you @592azy2circuitdude, I would like to see other solutions even with more transistors.

hurz

7 years ago

Not sure if the jury will exept my handicap 2 solution, lets see 😜 http://everycircuit.com/circuit/5807573214429184

jason9

7 years ago

It is not accepted because it uses a diode which was not listed as one of the valid components, and if you hold the button down the LED will turn on, but after a few seconds (really like 20uS real time) it turns off again and it only stays on if you let go before those few seconds are up, so it doesn’t qualify.

hurz

7 years ago

I know. BTW, 20u!s! and you can replace the diode with a transistor, but you have to tune all resistors as well and its then only a handicap 3 circuit.

592azy2circuitdude

7 years ago

Your circuit @hurz, makes a great digital frequency divider... Just like you can do with a jk-flip-flop. http://everycircuit.com/circuit/4818626795536384

592azy2circuitdude

7 years ago

Also, on your handicap 2 solution, it works very nicely with a 100pf capacitor instead of a diode. Is there a way to simulate a capacitor with transistors?

hurz

7 years ago

The original circuit is a 3bit counter ;-) as long as capacitors are not allowed in Jasons challenge, i have used a diodes as capacitor. Transistors do have from pin to pin 5picoFarad parasitic capacitance. So with one transistor you can get 10pF in total while a diode can be adjusted to 1nF 😜

jason9

7 years ago

A transistor can use miller effect to get up to 1nF or even above with high gain.

hurz

7 years ago

In theorie you can get 5nF from a single everycircuit BJT. Anyway, its a capacity with too high resistance to be a proper cap. But two times 5pF are perfect 10pF capacitance.

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