公司通常购买的所有雇员的一种类型的电话。但是，这意味着每个林格有相同声音，并且当一个电话响了，十几人暂停，看看他们的电话。同样令人讨厌的是没有的视觉消息指示器，所以任何人如怀疑他们可能有一条消息，必须举起手机，听听特别消息音。Maxim > App Notes > Audio Circuits Keywords: Chip Recorder Customizes Phone Ringer Sep 06, 2002 APPLICATION NOTE 1187 Chip Recorder Customizes Phone Ringer Companies usually purchase one type of telephone for all employees. But this means that every ringer has the same sound and when one phone rings, a dozen people pause and look at their telephones. Equally annoying is the absence of a visual message indicator, so anyone who suspects they may have a message must lift the handset and listen for a special message tone. By placing a circuit in series with the telephone (Figure 1), you can customize a phone ringer without modifying the phone. The heart of the ringer is a chip-recorder IC (U5) capable of playing up to 10 seconds of telep……