A flashing LED signals the necessity to water a plant Very low current consumption - 3V powered circuit Circuit diagram: Parts: R1, R4 470K 1/4W Resistors R2 47K 1/2W Trimmer Cermet or Carbon R3 100K 1/4W Resistor R5 3K3 1/4W Resistor R6 15K 1/4W ...
Build a dark-activated switch with only a triac, a photocell, and a resistor. Abel Raynus Assume that you have a device that receives its power from the main 120 or 220V-ac line and you need to add a switch between the ac line and the device so ...
Use this circuit to tell which game player presses a button first. Vasil Borodai The circuit in Figure 1 lets you indicate which game player presses a button first. Each button has a corresponding LED that indicates the pressing of the button. All ...
Continuous monitoring of the mains voltage is required in many ap- plications such as manual voltage stabilisers and motor pumps. An analogue voltmeter, though cheap, has many disadvantages as it has moving parts and is sensitive to vibrations. The ...
High sensitivity, portable temperature comparator detects draughts around doors, windows, etc. Circuit diagram: Parts: 22K Linear Potentiometer (See Notes) R2 15K @ 20 C n.t.c. Thermistor (See Notes) R3 10K ¼W Resistor R4, R5, R7, R9 22K ...