The 820K Ohm Resistor Quarter Watt 0.25W is a fixed resistor that has a resistance value of 820,000 ohms (820K ohms) and a power rating of 0.25 watts (quarter-watt). This resistor is designed for use in low-power electronic circuits, where it helps to control the current flow and divide voltages within the circuit. The 820K ohm resistor is commonly used in applications that require a high resistance value, such as voltage dividers, signal filtering, and sensing applications.

This resistor is ideal for applications that need to limit the current flow in circuits with higher voltage levels or where voltage drop is a critical aspect of the design. Its quarter-watt power rating ensures that it remains effective for low-power applications, making it a popular choice in hobby electronics, prototyping, and DIY projects.

Key Features:

• Resistance Value: 820K ohms, ideal for applications requiring a high resistance value to limit current or divide voltages in the circuit.
• Power Rating: 0.25W (quarter-watt), suitable for circuits that operate under low power and require minimal heat dissipation.
• Tolerance: Typically ±5% tolerance, though precision versions with ±1% tolerance may also be available for applications requiring higher accuracy.
• Compact Size: The quarter-watt form factor is perfect for breadboards, PCBs, and other space-constrained designs, ensuring ease of integration into a variety of setups.
• Material: Constructed from carbon film or metal oxide, offering excellent stability and reliable performance for low-power applications.

How It Works: The 820K Ohm Resistor Quarter Watt 0.25W works by restricting the flow of electrical current according to Ohm’s Law (V = IR), where V is the voltage, I is the current, and R is the resistance. A higher resistance like 820K ohms limits the amount of current that can pass through the resistor, which is essential in circuits where voltage division or signal conditioning is required.

For example, if 5V is applied across the 820K ohm resistor, the current flowing through it can be calculated as:

$$I = \frac{V}{R} = \frac{5V}{820,000Ω} \approx 0.0000061 \, A = 6.1 \, \mu A$$

This means that with a 5V supply, the current flowing through the 820K ohm resistor will be approximately 6.1 microamperes (µA), which is a very small current.

The power dissipated by the resistor can be calculated using the formula:

$$P = I^2 \times R$$

Substituting the calculated current:

$$P = (0.0000061 \, A)^2 \times 820,000Ω \approx 0.00025W = 0.25W$$

Thus, the resistor will dissipate 0.25 watts of power, which is exactly within the 0.25W power rating of the resistor.

Applications:

• Voltage Dividers: Used in voltage divider circuits to create specific voltage levels, often in sensor circuits, ADC inputs, or reference voltage generation for microcontrollers.
• Signal Conditioning: Ideal for signal filtering and attenuation in analog circuits, where high resistance is needed to reduce signal strength or smooth variations in the signal.
• Current Limiting: Can be used for current-limiting in sensitive components such as LEDs, where low current is required to prevent damage.
• Sensing: Often used in sensor interfaces to create high-resistance pathways in circuits that require high resistance for signal conditioning or voltage measurement.
• RC Circuits: Useful in Resistor-Capacitor (RC) circuits for applications such as timing and filtering where high resistance is necessary to determine the time constant of the circuit.
• Impedance Matching: Can be used for impedance matching in audio circuits, ensuring proper signal transfer and reducing signal loss.
• Power Supply Regulation: Employed in voltage regulation circuits to control or stabilize the voltage levels supplied to various components, especially in low-power designs.

Limitations:

• Low Power Rating: With a 0.25W power rating, this resistor is suitable for low-power circuits. If your application involves higher power dissipation, a higher-power resistor (e.g., 0.5W or 1W) should be used.
• Current Handling: This resistor is designed for low-current applications (e.g., microamperes to milliamps). For circuits involving higher currents, a lower resistance value and a higher power-rated resistor are required.
• Tolerance: With a ±5% tolerance, there is a slight variation in the actual resistance value. For high-precision applications, consider a precision resistor with ±1% tolerance or better.

The 820K Ohm Resistor Quarter Watt 0.25W is an important component for low-power applications that require a high resistance to control current flow and divide voltage levels. Whether used in voltage dividers, signal filtering, or sensor circuits, it offers stable performance with minimal power dissipation. Its compact size and reliable construction make it a valuable choice for hobbyists, engineers, and DIY electronics enthusiasts working on a variety of low-power projects.