Solar Cell Phone Charger
This little gadget uses a small 3 volt solar cell to charge a 6 volt NiCad battery pack which, in turn, may be used to charge many models of cell phones and other portable devices. The circuit "scavenges" energy from the solar cell by keeping it loaded near 1.5 volts (maximum energy transfer value) and trickle charges the internal battery pack with current pulses. The simple circuit isn't the most efficient possible but it manages a respectable 70% at 100 mA from the cell and 30% when the cell is providing only 25 mA which is actually pretty good without going to a lot more trouble or using more exotic components.
Resistor color codes
| How to read Resistor Color Codes Identifying the value of color coded resistors will become easy with a little practice, as there are only a few simple rules to remember. |  |
Fluid level control schematic diagrams
The LM1830 fluid level detector circuit is a device intended to signal the presence or absence of aqueous solutions, featuring low external parts count, wide supply operating range, internally regulated supply and AC or DC output.
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