Canon fax basic 2000 서비스 매뉴얼

BASIC OF TELEPHONE

1–6

2.1

Transmitter (Microphone)

The voice vibrates a diaphragm compressing/releasing carbon powder.

When carbon powder is compressed, its contact resistance decreases.

When the powder is released, its contact resistance increases. So direct

current varies corresponding to the change of pressure (voice). This is

called “voice current”. Recently, a microphone is applied to the transmitter

of the telephone.

Fig. 1-6   Transmitter and Voice Current

Carbon powder

Fixed electrode

Diaphragm

Air vibration

Contact
resistance

Voice current