Thyristor-LED-blink

382

08:03:39

Anyone knows why this circuit is not working as described here:
https://www.elektronik-kompendium.de/sites/praxis/bausatz_led-blitzer.htm

published 4 years ago

jason9

4 years ago

EC has trouble simulating thyristors. It always finds a “stable” point right on the edge of triggering the thyristor where the discharge rate equals the charge rate making it so that nothing happens. In reality this is an extremely unstable (and therefore unrealistic) state and a real thyristor would fully trigger instead of being in limbo between triggered and not triggered.

jason9

4 years ago

Also thyristors have something called a triggering current which is the minimum current required to trigger it. It appears that in this circuit EC is simulating a triggering current of 70μA but you’re only supplying 9μA of charging current, so it can’t trigger. I suppose that in real life a thyristor would likely have a triggering current below 9μA, otherwise this circuit would not work in real life.

jason9

4 years ago

Some googling reveals that the correct term here is latching current, and also that it varies widely between thyristors depending on how much current said thyristor is meant to carry.

kiani

4 years ago

Chk this,, your exact cct. But working https://everycircuit.com/circuit/5996672037158912

bolausson

4 years ago

Thanks a lot for the explanation jason9 and thanks a lot for the working example kiani. Verry appreciate!

kiani

4 years ago

Hope it all works out for you... @jason9 analysis is is correct to the details,, even the circuit works with actual part models, its a little iffy...

bolausson

4 years ago

Yes works perfectly, thanks again! I wasn't aware that you can chang all those details because the Android app doesn't show those parameters. They are only visible via a browser to me.

bolausson

4 years ago

Mmmh I now changed all components in this circuit to the same setting as in your (@kiani) circuit, but it below through the LED instantly. Did I miss something?

wyoelk

4 years ago

Speed up the simulator to 1s/s and select the led for the scope. These are the basic circuits I work with, the other folks know a LOT more than I! _ http://everycircuit.com/circuit/6425013445722112

bolausson

4 years ago

Argh... indeed it blows through the first time and then it works. I checked all settings except the simulation speed. Thanks! Now it works!

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.