I think one will fade in while the other fades out, before each transistor reaches saturation point. I'll try it tonight...How about this circuit. This should work keeping only one led on at a time.
I got something to work!Here's another option, using a 'long-tail pair' configuration.
View attachment 101639
It occurred to me that changing some things in the circuit may invalidate the value of that resistor, but the voltage didn't cross my mind. Changing the supply voltage will probably break it. Won't get to mess with it until tomorrow night.Nice work,
Yes, our designs used a linear transition, while yours is purely switching trasnsition, as what you were looking for, good job.
Now to increase this challenge a little, you said you had to tweak R5 a little.
Will a change of supply voltage cause R5 to be eratic again, if it does not, then you get the award for best design for this project.
But if it does, then were still in the game.
I'll try to come up with a design using a different discrete component, but lets say all this has to be done using only discrete components, makes for a more fun challenge.
please let us know what your results are in testing your circuit, for variable supply voltages.
Alec, I received a phototransistor yesterday, and don't know how much current it produces. When I applied it to Q1 (eliminating Q3 and Q4), it was not enough to flip the flop. (Configuration 1)How much current can your photo-transistor produce when illuminated? It would have to be ~4mA to pull the base of Q2 low enough to turn off Q2 and so light LED2. I think you'd need very bright light to get 4mA.
The circuit worked fine at 9V, too.please let us know what your results are in testing your circuit, for variable supply voltages.
Congratulations on a successful design on your circuit in post #44.The circuit worked fine at 9V, too.
Then I started building a variable regulated circuit (aiming for 1.25V to 12V), and didn't complete that task.
Further testing reveals that it breaks down above 9.8V. In low room light, L1 comes on and L2 stays on. So no congrats for me.Congratulations on a successful design on your circuit in post #44.
When you said you had to tweak R5, to get it behaving with the rest of the circuit, I was wondering how well it would track with varying supply voltages.
Good job in your design.
Some time breadboard my latest circuit and see if it works also,
as alec t said (I think he was referring to my last posted circuit), that it may take a lot of light to bring Q2's base down through the photo trans.
If it does than you may have to put some emitter resistance on Q2, to raise its base voltage higher above ground.
by Aaron Carman
by Aaron Carman
by Jake Hertz