Lidmotor's Penny circuit help needed.

[TinselKoala]

The video showed what I meant by 28ma and .7v and 1v I don't consider too much voltage but I think this circuit does.

Are you talking about where you changed the LED model component parameters from 20 mA to 28 mA?

What that number means is that, at a supplied DC voltage of 3.4 V (or whatever you are putting into the LED parameters), the LED _model_ is designed to draw 20 mA of DC current and produce the rated light output. I don't think this has anything to do with what your circuit is producing. By raising this current value you are essentially lowering the forward voltage of the LED model component, I think.
I have found that higher forward voltages usually work better for light output. In fact, by putting two LEDs in series, one can often get better performance. This is why most JTs use the higher voltage white or blue LEDs rather than red or green ones, I think. Why don't you try _lowering_ this current value in your LED model and see what happens? Or you could try raising the LED model's voltage to 6 volts, keeping the 20 mA current value.

[TinselKoala]

The LED will have a published "forward voltage" that describes the voltage needed to put a certain small current through the LED. Above that stated forward voltage the relationship between the supply voltage and the current through the LED will look like the graph below. This is for a red LED with a rated "forward voltage" of about 1.7 V, but your blue LED will have the voltage values higher, but the shape of the curve will be the same. Your simulator model is setting the curve to hit the point at 3.4 V at 20 mA. So when you change the value to 28 or 29 mA, you are essentially moving the curve to the left: the voltage values needed to produce a given current in the LED decrease.

[Dark Alchemist]

Are you talking about where you changed the LED model component parameters from 20 mA to 28 mA?

What that number means is that, at a supplied DC voltage of 3.4 V (or whatever you are putting into the LED parameters), the LED _model_ is designed to draw 20 mA of DC current and produce the rated light output. I don't think this has anything to do with what your circuit is producing. By raising this current value you are essentially lowering the forward voltage of the LED model component, I think.
I have found that higher forward voltages usually work better for light output. In fact, by putting two LEDs in series, one can often get better performance. This is why most JTs use the higher voltage white or blue LEDs rather than red or green ones, I think. Why don't you try _lowering_ this current value in your LED model and see what happens? Or you could try raising the LED model's voltage to 6 volts, keeping the 20 mA current value.

I started it at 5ma it worked even better and there is no way to change the foward voltage in multisim.  I could try to make a brand new model but I tried that a few days ago to a dismal failure.

[Dark Alchemist]

The LED will have a published "forward voltage" that describes the voltage needed to put a certain small current through the LED. Above that stated forward voltage the relationship between the supply voltage and the current through the LED will look like the graph below. This is for a red LED with a rated "forward voltage" of about 1.7 V, but your blue LED will have the voltage values higher, but the shape of the curve will be the same. Your simulator model is setting the curve to hit the point at 3.4 V at 20 mA. So when you change the value to 28 or 29 mA, you are essentially moving the curve to the left: the voltage values needed to produce a given current in the LED decrease.

As I said it works from 1ma all the way to 28ma but not beyond with the Blue LED (3.45v)

[TinselKoala]

I started it at 5ma it worked even better and there is no way to change the foward voltage in multisim.  I could try to make a brand new model but I tried that a few days ago to a dismal failure.

Well, there you go then, this confirms what I said. Lowering this current value effectively moves the graph to the right, in other words raises the forward voltage.
Don't make a new model, just put 2 or 3 LEDs in series in your sim circuit, this will effectively raise the forward voltage. Think of it like raising the height of a dam. The blocking oscillator needs to have a voltage swing, and when your LED turns on and passes current this limits or clips the voltage level of the swing. If you put two in series you are raising the height of the "dam" so that the voltage swing when the dam overflows is greater, and contains more power.