FLED-based solar engines

MisterBill2

Joined Jan 23, 2018
11,602
Two things here,First, using an uncommon acronym is a poor choice, and second, in this instance it is a VERY POOR CHOICE.
It appears in that linked article that it is used a a voltage sensitive trigger for a circuit momentarily pulsing a motor.

It may be that currently available flasher LEDs are different from the one in that linked article. And it is likely that there are better ways to trigger on voltage rise.
So while it may work, why bother???
 

BobTPH

Joined Jun 5, 2013
4,769
I'm curious now - what is the solar panel voltage and how big is the motor?
He is talking about the little toys that charge a caoacitor through a small solar panel (like from a calculator) then discharge the cap through the motor for a little bit if movement.

Bob
 

Thread Starter

Lucky-Luka

Joined Mar 28, 2019
165
Two things here,First, using an uncommon acronym is a poor choice, and second, in this instance it is a VERY POOR CHOICE.
It appears in that linked article that it is used a a voltage sensitive trigger for a circuit momentarily pulsing a motor.

It may be that currently available flasher LEDs are different from the one in that linked article. And it is likely that there are better ways to trigger on voltage rise.
So while it may work, why bother???
ok then what alternatives do you suggest?
 

Ian0

Joined Aug 7, 2020
4,863
The circuit is a very simple MPPT. In order to get the maximum power out of the solar panel, the panel voltage has to be kept at about 85% of its open-circuit voltage, so discharging it down to 1V is very inefficient. What is required is much less hysteresis (maybe 250mV) and much more capacitance. I also suspect that there is very little spare power to run the circuitry.
 

Thread Starter

Lucky-Luka

Joined Mar 28, 2019
165
The circuit is a very simple MPPT. In order to get the maximum power out of the solar panel, the panel voltage has to be kept at about 85% of its open-circuit voltage, so discharging it down to 1V is very inefficient. What is required is much less hysteresis (maybe 250mV) and much more capacitance. I also suspect that there is very little spare power to run the circuitry.
They are basically toys... Do you suggest me using something else other than FLEDs?
 

BobTPH

Joined Jun 5, 2013
4,769
The circuit is a very simple MPPT. In order to get the maximum power out of the solar panel, the panel voltage has to be kept at about 85% of its open-circuit voltage, so discharging it down to 1V is very inefficient. What is required is much less hysteresis (maybe 250mV) and much more capacitance. I also suspect that there is very little spare power to run the circuitry.
The panel is incapable of running the motor continuously, hence the charge / discharge cycle.

Bob
 

Ian0

Joined Aug 7, 2020
4,863
The panel is incapable of running the motor continuously, hence the charge / discharge cycle.

Bob
Exactly, an MPPT would keep the panel voltage at the optimum for maximum power by adjusting the output current.
This is my suggestion.
Current source plus 6x1N4001 makes a simple simulation of a solar panel.
1H + 1Ω simulates the motor.
I note that the reverse diode across the motor is missing from the original circuits. It would be essential to prevent damage to the drive transistor, but it is important to allow the current to continue to circulate in the motor.

Screenshot at 2022-01-03 12-44-05.png
 

MisterBill2

Joined Jan 23, 2018
11,602
The switching rate of the transistors and the low inductance of the small motor make the turn-off "spike" much smaller in such a motor. In addition, the voltage ratings of most transistors exceed the level of such a pulse of a small motor.
 

Thread Starter

Lucky-Luka

Joined Mar 28, 2019
165
Exactly, an MPPT would keep the panel voltage at the optimum for maximum power by adjusting the output current.
This is my suggestion.
Current source plus 6x1N4001 makes a simple simulation of a solar panel.
1H + 1Ω simulates the motor.
I note that the reverse diode across the motor is missing from the original circuits. It would be essential to prevent damage to the drive transistor, but it is important to allow the current to continue to circulate in the motor.

View attachment 256724
What are you using instead of the FLED to create the trigger effect?
I don't understand the benefits of your configuration.
 

Ian0

Joined Aug 7, 2020
4,863
What are you using instead of the FLED to create the trigger effect?
I don't understand the benefits of your configuration.
Regeneration or positive feedback. It gives better accuracy. When the voltage on the R1/R2 divider is high enough to turn Q2 on, R4 gives it extra bias and switches Q1 fully on.
 
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