pins 2 and 3, which would likely cause permanent damage if applied to a dynamic or ribbon microphone. Plug-in-power (PiP) is the low-current 3–5 V supply provided at the microphone jack of some consumer equipment, such as portable recorders and computer sound cards. It is also defined in IEC 61938. It is unlike phantom power since it is an unbalanced interface with a low voltage (around +5volts) connected to the signal conductor with return through the sleeve; the DC power is in common with the audio signal from the microphone. A capacitor is used to block the DC from subsequent audio frequency circuits. It is often used for powering electret microphones, which will not function without power. It is suitable only for powering microphones specifically designed for use with this type of power supply. Damage may result if these microphones are connected to true (48 V) phantom power through a 3.5 mm to XLR adapter that connects the XLR shield to the 3.5 mm sleeve. Plug-in-power is covered by Japanese standard CP-1203A:2007. A similar line-powering scheme is found in computer sound cards. Both plug-in-power and soundcard power are defined in the second edition of IEC 61938. These alternative powering schemes are sometimes improperly referred to as "phantom power" and should not be confused with true 48-volt phantom powering described above. Some condenser microphones can be powered with a 1.5-volt cell contained in a small compartment in the microphone or in an external housing. Phantom power is sometimes used by workers in avionics to describe the DC bias voltage used to power aviation microphones, which use a lower voltage than professional audio microphones. Phantom power used in this context is 8–16volts DC in series with a 470ohm (nominal) resistor as specified in RTCA Inc. standard DO-214. These microphones evolved from the carbon microphones used in the early days of aviation and the telephone which relied on a DC bias voltage across the carbon microphone element. Other uses Phantom power is also used in applications other than microphones: Active antennas Low-noise block downconverter Power over Ethernet Notes See also Bias tee Power line communication, data communication over mains electricity References External links The Schoeps CMT 20 microphone of 1964 – the world's first phantom-powered microphone Phantom Powering – Balanced Lines, Phantom Powering, Grounding, and Other Arcane Mysteries. Loud Technologies Inc, 2003 Powering microphones – a collection of information and circuits for powering