1. Resistance Value: Megaohm resistors have resistance values that range from one million ohms (1 MΩ) to several millions of ohms (1.5 MΩ 1.8 MΩ, 2.2 MΩ, 3.3 MΩ, etc.). The resistance value is indicated by the numeric value followed by the "MΩ" symbol on the resistor's color code or label.
2. Purpose: Megaohm resistors are used for various purposes in electronic circuits:
Voltage Dividers: They are commonly used in voltage divider circuits to divide a higher voltage into a lower voltage for measurement or reference purposes.
Signal Conditioning: In some applications, high-impedance input or output circuits are needed to prevent loading effects on the circuit being measured or controlled. Megaohm resistors can be used for such high-impedance applications.
Leakage Current Control: In some cases, megaohm resistors are used to control or limit leakage currents in electronic circuits.
Noise Filtering: High resistance values can be used in filter circuits to minimize the impact of noise or interference.
3. Tolerance: Like standard resistors, megaohm resistors come with tolerance values that indicate the range within which the actual resistance may vary from the specified value. Common tolerance values for these resistors include 1%, 5%, and 10%.
4. Types: Megaohm resistors can be found in various types, including through-hole resistors (which have wire leads for soldering onto a circuit board) and surface-mount resistors (SMD) that are soldered directly onto the surface of a circuit board.
5. Material: The material used in megaohm resistors can vary but often includes metal film, metal oxide, or carbon composition.
6. Color Coding: Like lower-value resistors, some megaohm resistors may use color coding to indicate their resistance value and tolerance. However, color coding may not always be practical for very high-value resistors, and they are often labeled directly with their resistance value.
7. Common Applications: Megaohm resistors find use in a wide range of applications, including in medical devices, high-impedance amplifiers, instrumentation, environmental monitoring equipment, and more.
8. Testing: High-value resistors like megaohm resistors can be sensitive to environmental factors and contamination. They may require special handling and testing procedures to ensure their accuracy and stability over time
