I just purchased an All Powers solar power bank, but my little project doesn't draw enough amps to keep the power bank on. I found this circuit, but I can't test it because I don't have a PNP transistor, is there a way to re-write this circuit using only NPN transistors?

Original Circuit:
https://dorkbotpdx.org/blog/paul/battery_pack_load

I'm also uploading the diagram of the circuit.


Thanks for your help.

 

Use a 100Ω ½W resistor.

 

Use a 100Ω ½W resistor.

You mean, in place of the PNP transistor in the circuit?

 

You mean, in place of the PNP transistor in the circuit?

In place of the whole circuit.

 

Thanks MrChips, I'm sure that will work.

Just out of curiosity, using the 100ohm 1/2 watt solution will drain the battery faster right?

It seems like it would, but I've been duped by assuming things before.

 

Thanks MrChips, I'm sure that will work.

Just out of curiosity, using the 100ohm 1/2 watt solution will drain the battery faster right?

It seems like it would, but I've been duped by assuming things before.

Sorry, I went back and looked at the blog where the circuit originated. I did not understand the function of the circuit. The circuit is an oscillator meant to draw current at intervals with a long time delay. Changing the PNP transistor to NPN will not work. My apologies.

Google NPN oscillator circuit.

 

Yup, that's what I needed. Thanks.

 

Here are two different circuits that are meant to accomplish the same thing, i.e. pulse the LED at fixed intervals.
You will have to adjust the time delay and current draw to achieve your desired objectives.

 

Cool Thanks.

Is it the 100K resistor that id handling the large current draw, or the LED?

 

It is the 100Ω resistor in series with the LED. If you need to reduce this value to say 22Ω you will have to eliminate the LED otherwise the LED will die of excessive current.

The LED is there only to indicate the pulse interval which is about 1½ seconds with those component values.