I just bought a very small aerator called "Metal Marine Bubble Box" that runs off a small DC motor. Not much torque needed. I tried reading the print on it and all I could read was 1.5v. This makes sense since it takes 2 D batteries which are 1.5v. With both batteries can run for 40 hours, but it can also run on 1 D battery for 20 hours. I know a D battery's current is about 25mA. I want to eliminate batteries.
I want to build a solar cell/panel that can run it instead of using batteries, or that also will charge the batteries while running it, or something like that.
I've seen someone create a small fan from a dollar tree/store solar garden light but couldn't tell exactly how they did it.
What do I need to build it (diodes, resistors, etc.)? I'm a noob and know nothing about circuits, voltage, current needed to run this tiny motor. I'm wondering if I have to perfectly match the voltage/current.
Best Answer
Assuming you only need 25mA (big if), then yes it's likely that you can do this easily, the same way others have. You may need a solar panel with a larger current output to charge the battery, and the device may not like the lower voltage of a rechargeable battery chemistry.
simulate this circuit – Schematic created using CircuitLab
The first is a very basic. Dollar store (And more expensive) solar garden lights at this time use a led driver IC that also does turning on and off based on light and boost circuit for driving a 3V led, but essentially the same as this.
The second is a better idea. A stronger solar panel charging multiple batteries in series, and a voltage regulator to bring down the voltage to what your device needs.
Even if you need more current, the same still applies. You will just need a much better/larger solar panel. Maybe 12V 3W? The regulator option will be required at that point.