Today, My son make a toy for younger sister. It is a Simple big robot toothbrush. The principle is very simple, It vibrates with movement, without direction and control. He took it to play with the cat great fun. Figure 1 the Simple big robot toothbrush He uses all old parts. – The power source is a AA batteries 1.5V x 2 = 3V. Because he uses a DC motor in a toys. Which, it uses voltage about 1.5V – 4.5V. – ON-OFF Switch, we use a small switch. – All parts is hold on the plastic board with glue. …
This is simplest automatic solar led light circuit that my son try to make it for basic small solar charger. This circuit is a simplest circuit. He trial it to learn about solar LED light, and makes it all by himself. He needs one LED light that brightest at night. But in daytimes it will go out and charged current to battery. He choose to use 2 x AA nickel-metal hydride battery total voltage is 2.4V at 500mAh. It need to used current about 50mA – 80mA. Thus he cannot use a white LED because it use 3.3-3.6V. As this …
This is simple hight power LED flashlight,we use 24 LEDs super bright for display and 3 AA batteries and resistor for limit current so cheaper. My son buy this LED flashlight but is low light. Thus, he want to builds the new high power LED flashlight with himself. How does it works We use the 24 white super bright LEDs. As circuit diagram in Figure 1. They are connected together in parallel. The each LEDs need to use the voltage about 3.3V – 4V at 20mA current. It makes LEDs uniform brightness, but use all current are 0.4A to 0.6A. …
This is a simple Solar plant watering alarm circuit. It will sound alarms when the soil is dry. The trees have died. It the solar sell is 6V DC power supply. Thus saving convenience and does not require batteries.No noise at night. How the circuit works As circuit diagram in Figure 1 Figure 1 the circuit diagram of the Solar plant watering alarm. Hand draw use AAx3 batteries 4.5V The main principle is that when the soil is dry, with high resistance. However, when the soil is wet with minimal resistance. Usually the wet soil will have resistance is about …
This is a fast blinking LED bike light circuit For safety when the bike at night. We use two-NPN-PNP transistor oscillator circuit and RC circuit only show on 4 LEDs use low current. We take the four LEDs to parallel because each LED use voltage about 3 – 4.5V We want this circuit for long time using so use the LED voltage is 3V only. And makes them to blinking as the LED flasher. Figure 1 Testing the LEDs in parallel. They use current about 0.077A. But we use them in switching so low Figure 2 the circuit diagram of …