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Circuit components for use in audio/video equipment -- products and standards

UL tests various types of circuit components for use in audio and video appliances. The main component categories are:

• Across-the-line capacitors, antenna coupling, and line-by-pass components
• Conductive path resistors
• Fusing resistors and temperature limited resistors
• Special fuses
• High voltage components

Across-the-line capacitors, antenna coupling, and line-by-pass components

• UL 1414, the Standard For Safety For Capacitors For Radio and Television Type Appliances. These requirements cover:
  • Capacitors rated not more than 1.0 microfarad, 85 degrees C, 250 volts, and 60 hertz
  • Double protection capacitors rated not more than 0.5 microfarad, 85 degrees C, 125 volts, and 60 hertz
  • Varistors and gas-tube voltage surge suppressors intended for use in circuits not rated more than 250 volts, and 60 hertz

All of the above are intended to be employed in radio, television receiving, and similar appliance circuits where breakdown of the capacitor may result in a risk of fire, electric shock or personal injury.

Conductive path resistors

Resistors are used to provide an electrical conductive path between the antenna and the supply circuit of a radio, video, or television-type appliance. The resistors are intended to reduce the risk of fire or electric shock due to the buildup of a static electrical charge on the antenna connected to the appliance.

• UL 1676, the Standard For Safety for Discharge Path Resistors. Under this Standard, the supply circuit must not be rated more than 250 V, 50-60 Hz. The resistors themselves must meet the following specifications:

Fusing resistors and temperature limited resistors

• UL 1412, the Standard for Safety for Fusing Resistors and Temperature-Limited Resistors. These requirements also apply to mounting assemblies. The purpose of these requirements is to reduce the risk of fire or electric shock. Resistors that comply with these requirements, however, are not acceptable for use in all applications without evaluation in the appliance. These components are intended for use in circuits that do not involve potentials greater than 2500 V peak.

Special fuses

• UL 1417, the Standard for Safety for Special Fuses for Radio And Television Type Appliances is used to evaluate these types of products. The requirements in UL 1417 apply to special types of fuses not covered by separate requirements and that are for use in radio and television-type appliances where they are relied upon to limit power or current or both. These requirements also apply to holders intended to accept such special fuses where the holder may be an integral part of the fuse design. Compliance of a special fuse with these requirements does not assure that it is acceptable for use as a protective device in the end-use product.

High voltage components

• UL 1413, the Standard for Safety For High-Voltage Components For TV-Type Appliances is the Standard used to test these types of components. Examples of these components include: flyback transformers, high-voltage multipliers, deflection yokes and picture-tube high-voltage-neck components. High voltage is defined as a potential equal to or greater than 2500 V peak.

Additional tips

• UL classifies circuit components that meet UL's requirements as "Recognized Components." Once they meet the appropriate UL requirements, they will be authorized to bear the Recognized Component Mark.