I understand what hysteresis is ok from this forum. I just cant do calculations and equations to measure hysteresis and what voltage and currents go where due to complexity of the circuit itself.

Calculating the hysteresis requires a more detailed look at the circuit than can be gleaned from a simple model like I used to provide a qualitative description.

I would recommend looking at the small-signal model of the circuit. That may let you see how to come at the hysteresis calculation, but maybe not. I'd have to do it to convince myself one way or the other and I just don't have the time right now.

 

I did not do any math to see the positive feedback that makes it non-linear, so that it tends to jump. The detailed math is indeed a bit tricky.

 

GW PSLM32.UL is a 100mA led that would be 60 ohm but that is not going to act anything like a 60 ohm load the OP should add a resistor before the led like 24 ohm 1/4 watt
R = V / I = 6V / 0.1A = 60Ω
P = V×I = 6V×0.1A = 0.6W

 

GW PSLM32.UL is a 100mA led that would be 60 ohm but that is not going to act anything like a 60 ohm load the OP should add a resistor before the led like 24 ohm 1/4 watt
R = V / I = 6V / 0.1A = 60Ω
P = V×I = 6V×0.1A = 0.6W

Evidently the actual circuit works quite well, but the simulator has no LED model. A substitute in the simulation would be three 1N4000 diodes in series.

 

Evidently the actual circuit works quite well, but the simulator has no LED model. A substitute in the simulation would be three 1N4000 diodes in series.

He's using LTSpice, which comes with about a dozen LED models.

 

He's using LTSpice, which comes with about a dozen LED models.

Its this type of led. I dont see in LTSPICE

 

Its this type of led. I dont see in LTSPICE

View attachment 339805

Who is the manufacturer?
Is there a Model Number?

 

Who is the manufacturer?
Is there a Model Number?

ors from Ali Express made in China. I dont know. Why do you ask?

 

You don't need the exact model in LTSpice just grab something close and add the dropping resistor.

 

Don't need the LED in the sim.
The LED is 3 volts at 100ma = 30 ohms.
The supply is 6 volts hence the LED is represented by a 60 ohm resistor.

 

OK, that is not the type of LED I was thinking about. BUT my suggestion of three power diodes in series will be a fair substitute. In addition, that is not the part of the circuit that the question is about.

 

hhsting,
Do you understand the purpose of R5 now and how it was calculated?

 

@hhsting,
Circuit is tuned for 6 V power supply.
LED1 LXML-PE01 has the same parameters as LED filament No.4015 - 2.8 V at 100 mA.

 

Out of all resistors in post #1 circuit, what would be the worst case power of resistor in watts i would need to buy in post #1 circuit?

 

1/4 watt will suffice for all except if there is a resistor in series with the LED. Is there?

 

1/4 watt will suffice for all except if there is a resistor in series with the LED. Is there?

The 60 ohm resistor is the led.

 

Yes on the schematic but is the LED is rated for 6 volts?

 

Yes on the schematic but is the LED is rated for 6 volts?

Led is rated 3v. Two of them in series make 6v

 

Has anyone actually constructed the circuit post #1 real life? I did and I am getting Q1 vbe of 1.0A with 0.66V. The V2 is 0.1vdc. My led light wont turn on.

 

Yes I have. It works as designed.
The LED should only come on if the voltage on the base of Q1 is below appx .6 volts.