(yet another) Power Bank Stay-On Circuit

[ElectricPower]

I agreed.

I just do not know why i should use an microcontroller for this.

My circuit works perfectly. But i know that other power banks may force me to do som tweaks regards to puls time and load etc.

~100mA pulse that last about 1 second or more is all that takes. I have tested this on four different powerbanks and it works. But i do not say that it works an all powerbanks. For that we possibly need to change a couple of resistors. No problem.

[mino-fm]

I just do not know why i should use an microcontroller for this.
My circuit works perfectly.

I don't know why I should use an ICM7555 for it.
A simple resistor (47 Ohm) works perfectly 

[ElectricPower]

I just do not know why i should use an microcontroller for this.
My circuit works perfectly.

I don't know why I should use an ICM7555 for it.
A simple resistor (47 Ohm) works perfectly 

Because it's waste of power?

[Zero999]

I just do not know why i should use an microcontroller for this.
My circuit works perfectly.

I don't know why I should use an ICM7555 for it.
A simple resistor (47 Ohm) works perfectly 

Because it's waste of power?

The 7555 typically only uses 40µA, 300µA at extreme temperatures, which is more than an MCU, but low enough not to matter in most applications.
https://www.nxp.com/docs/en/data-sheet/ICM7555.pdf

[ElectricPower]

I just do not know why i should use an microcontroller for this.
My circuit works perfectly.

I don't know why I should use an ICM7555 for it.
A simple resistor (47 Ohm) works perfectly 

My 7555 use 2.5mA.....

Maybe i got an fake part. But 2.5mA is not much anyway...

But it's a lot better than using just an resistor. I think.
Because it's waste of power?

The 7555 typically only uses 40µA, 300µA at extreme temperatures, which is more than an MCU, but low enough not to matter in most applications.
https://www.nxp.com/docs/en/data-sheet/ICM7555.pdf

[mino-fm]

The 7555 typically only uses 40µA,

ATtiny only needs 7 µA @ 5 V. I am the winner

You cannot solve a problem only looking at one minor point. You have to see the whole current consumption of wakeup-circuit and internal losses of powerbank which nobody really knows.
Further on: the main point is keeping powerbanks alive. The timing shown for ICM7555 would only work for one of my four powerbanks. So it is only a trial but not a useful solution for other users.

You are using large capacitors of 10 µF. Did you consider their initial value of +/- 20% (I guess) or their temperature drift? If you like to power GPS-trackers they have to work outside not knowing about temperature or humidity.

Myself I startet with RC-circuits to keep it simple. But going on it was no fun to adjust the timing for other PBs again and again. Optimizations of timing worked over night but failed at sunshine. It's been a pain
Be happy to get your PBs working. But only a microcontroller can ensure stable and adjustable timing in different environments at low costs.

[Zero999]

The 7555 typically only uses 40µA,

ATtiny only needs 7 µA @ 5 V. I am the winner

You cannot solve a problem only looking at one minor point. You have to see the whole current consumption of wakeup-circuit and internal losses of powerbank which nobody really knows.
Further on: the main point is keeping powerbanks alive. The timing shown for ICM7555 would only work for one of my four powerbanks. So it is only a trial but not a useful solution for other users.

You are using large capacitors of 10 µF. Did you consider their initial value of +/- 20% (I guess) or their temperature drift? If you like to power GPS-trackers they have to work outside not knowing about temperature or humidity.

Myself I startet with RC-circuits to keep it simple. But going on it was no fun to adjust the timing for other PBs again and again. Optimizations of timing worked over night but failed at sunshine. It's been a pain
Be happy to get your PBs working. But only a microcontroller can ensure stable and adjustable timing in different environments at low costs.

It's not my circuit.

There are plenty of ways to do this. You say you tested your circuit with several, but that doesn't mean it'll work for any power banks. I doubt there's a solution which will work for all power banks, without draining the battery too quickly.

I very much doubt stable timing is required. A potentiometer should suffice. Heck I'd probably just use a couple of transistors, or something like that. I'm not anti-MCU, but in this case having to reprogram it, for different power banks, would be too much of a fag, especially if I'm away and don't have the programmer handy. If I were to go down the MCU route, I'd do something more elaborate and allow the user to program the on/off time and current. 

[SilverSolder]

Is it an option to open the power bank and modify it to work as it should?

Maybe a physical switch and a small voltage regulator IC is all it would take?

[ElectricPower]

Works like a sharm


host gif online

[mino-fm]

If I were to go down the MCU route, I'd do something more elaborate and allow the user to program the on/off time and current.

I did so.