Product Description
MZ7 series PTC thermistors are used in the degaussing circuits of color TVs, computers, game consoles, monitors, and computer displays to make color images more vivid and clearer.
Specification
Product Name: MZ7 PTC Thermistor
Rated Resistance : 7-14Ω
Rated Voltage : 220V
Max Voltage : 270V
Withstand Voltage: 360V
| Item | MZ72 | MZ73 | MZ74 | ||||||
| Rated Resistance(Ω) | 7 | 9 | 12 | 7 | 9 | 12 | 14 | 7 | 9 |
| Tolerance(%) | ±20，±30 | ±20，±30 | ±20，±30 | ||||||
| Rated Voltage | 220V | 220V | 220V | ||||||
| Max Voltage | 270V | 270V | 270V | ||||||
| Starting current A(P-P) | ＞27 | ＞24 | ＞24 | ＞26 | ＞24 | ＞24 | ＞24 | ＞22 | ＞20 |
| Residual current 180SmA | ＜50 | ＜40 | ＜40 | ＜10 | ＜10 | ＜10 | ＜10 | ＜45 | ＜45 |
| Withstand Voltage | 360V | 360V | 360V | 360V | 360V | 360V | 360V | 360V | 360V |
Features
1. Specific Curie Temperature:
The Curie point of a PTC for degaussing is typically designed between 50°C and 60°C. This temperature is well below the damage threshold for the PTC itself or surrounding components, yet ensures a significant change in resistance within a very short period of time.
2. Extremely High Initial Cold Resistance:
At room temperature (cold state), its resistance is very low, typically only a few ohms to tens of ohms. This allows for a very strong surge current (up to 10 amps or more) to be generated at power-up, creating a powerful alternating decaying magnetic field for degaussing.
3. Rapid Temperature-Resistance Change Characteristics:
After power is applied, the strong current causes the PTC to rapidly heat up within 0.5 seconds to several seconds, exceeding its Curie point. Once the Curie point is exceeded, its resistance increases dramatically (to several thousand ohms), quickly limiting the current to a very low level (typically less than 1 mA).
4. Self-Heating & Self-Holding:
After demagnetization, the PTC thermistor remains in a high-resistance state, relying on a small holding current to maintain its high temperature and high resistance. The heat generated by this holding current balances with the ambient temperature (heat dissipation), stabilizing its temperature near the Curie point.
5. Auto-Resetting:
When the device is turned off and power is disconnected for a period of time (usually several minutes), the PTC thermistor cools down and its resistance automatically returns to its initial cold, low-resistance state, preparing for demagnetization upon the next power-on.
Application
Secondhand Market and Old Equipment Maintenance: A large number of CRT devices are still in use.
Industrial and Professional Fields: Certain precision instruments, laboratory equipment, and high-precision machine tools still require demagnetization to ensure measurement or processing accuracy, and the principles are similar.
Expanding the Principle: This PTC inrush current characteristic is also used in other starting circuits requiring instantaneous high currents, such as compressor starting devices.
