中文说明：
ISD1420为美国ISD公司出品的优质单片语音录放电路，由振荡器,语音存储单元，前置放大器，自动增，益控制电路，抗干扰滤波。
English Description：
ISD1420 is a high-quality single-chip voice recording and playing circuit produced by ISD company of the United States. It consists of oscillator, voice storage unit, preamplifier, automatic amplification, benefit control circuit and anti-interference filtering.