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触摸式电子门铃 普通电子音乐门铃电路见图1,其中KD9300是最常见的一种音乐集成电路。按图1接好电路后每按一次按钮开关SA,扬声器中就播放一首乐曲。我们也可以不用按钮开关SA,改用一种触摸开关,其电路如图2所示。PC是一小块印刷电路板,覆铜面腐蚀成叉指状,也可用刀刻法制成,面积约3×3 cm~2。VT1、V是两只高β值的三极管,最好在200倍以上,但是要求穿透电流I_(CEO)极小(用万用表的×10k挡测三极管的c、e两端,红表棒接e,黑表棒接c,表针应该丝毫不动)。按图2所示的电路接好后,将图2中的a、b两端分别接至图1的a、b两端,一只灵敏的触摸开关就做好了。使用时只要用手指触摸印刷电路板PC,扬声器中就会播放出优美的乐曲。
Touch electronic doorbell ordinary electronic music doorbell circuit shown in Figure 1, of which KD9300 is the most common kind of music integrated circuits. Press Figure 1 connected to the circuit after each press the button switch SA, the speaker will play a song. We can also switch without using the button SA, switch to a touch switch, the circuit shown in Figure 2. PC is a small printed circuit board, copper surface corrosion into the interdigital fingers, knife can also be made of law, an area of about 3 × 3 cm ~ 2. VT1, V are two high-β value of the transistor, preferably 200 times more, but the penetration current I_ (CEO) is extremely small (with a multimeter × 10k blocked transistor triode c, e ends, e, black bar then c, hands should not move). According to the circuit shown in Figure 2 is connected, the Figure 2 a, b are connected to both ends of Figure 1, a, b, a sensitive touch switch is done. Just touch the printed circuit board PC with your finger, the speaker will play a beautiful song.