Portable Field Tester part 3, making a solar power supply:
This part will be written by my daughter Chrystal, she is looking after making the power supply for our field tester (With my guidance).
Hi everyone, my name is Chrystal and I am 14 years old. My dad has helped me with this part by explaining diodes, resistors and how electricity works. I will explain each picture in detail as they are posted.
Diodes:
They allow electricity to pass only one way. So the power coming from our solar panel to the chargeable batteries have a diode soldered in (Silver ring end of diode towards the batteries). This stops the charged batteries from forcing electricity back up the wire to the solar panels.
The power supply I made is only for testing as my solar panel I have is not strong enough to power the project. As shown below we are only getting 2V from our small panel. We added a volt meter (I, with Dad's help, built it from a kit) with a push button to display the voltage. The volt meter is powered by a 9 volt battery (This is a waste of energy and won't be battery run in the final project), the push button only displays the volts for the length of time pressed (Saves some energy from being wasted).
The 150 Ohm resistor is to being the 9 volt battery down to the 5 volts required to run the volt meter. The resistor isn't exactly what we should have used as it drops us down to 4.6 volts but still works good (I should have used a 130 OHM resistor).
Recharger Wires:
So the picture above (Mess of wires) I will explain how this works. The green panel behind the battery is the backside of the solar panel. There are 2 red wires and 2 black wires attached, 1 red and black to the battery charger and the other 2 go to the volt meter. The positive red wire that goes to the charger has the diode. It is attached to the positive side of the charger. The negative wire is attached to the negative on the charger.
Volt Meter Wires:
The other red and black wires go to the volt meter test end. I wired it wrong the first 3 times, I hooked it up to the power side which didn't work, then reverse to the test side (Dad finally explained what I did wrong... I learned a lot from this mistake). The positive rom the battery with the resistor attached went to the positive on the volt meter and negative to negative. Oh, I almost forgot to say I put a push button on/off switch in the positive wire of the volt meter.
Working solar energy:
After it was all together I tested it. The panel was put in the light and I pressed the button...... It worked, 2 volts shown!!! I did it, except..... I require around 9 volts to run everything (Beaglebone, TI's, sensors.... 
) My solar panel is to small for the energy I require to collect.
Conclusion:
The power supply worked great but I require a bigger or more panels to reach the required volts. Dad just informed me he had ordered the panels we required so when they arrive I will make this run our Field Tester.
More to come,
Chrystal W.
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