目前国内一般中小单位只有1～2部电话,非常不便,所以很多单位加装了电话副机,使一部电话变成2部,并接副机的电路有2种,图1为简单并联,图2为人工闸刀控制,但2种都有缺点,图1的接法为香港及国际上通用接法,它的缺点是:1.当分机拨电话号码时,主机便会发出一连串令人烦恼的叮……叮声,这是由于分机拨号码时的脉冲电压触发主机内电铃所致。2.另一问题是不论利用 At present, there are only 1 or 2 phones in the country, so it is very inconvenient for many small and medium-size units. Therefore, many units have installed a telephone accessory so that one phone can be converted into two phones and two accessory phones. Figure 1 shows the simple parallel connection, Figure 2 is a manual knife control, but both have shortcomings. The connection of Figure 1 is a universal connection in Hong Kong and internationally. The disadvantages are: 1. When the extension dials the phone number, the host sends out a series of errors Trouble bite ... ... bite, which is due to extension of the dial number when the pulse voltage triggered by the bell within the host. Another problem is that no matter use