Lesson 16--Microduino "Fingertip switch (transistor trigger)"

Language	English

Objective Maybe you hit that sometimes accidentally touch the led will light up in the experiment. That is because the human body resistance to leds light up. During DIY phototransistor, as long as give in a samll voltage to NPN transistor's base,the triode will be connected, achieve the purpose of the switch, so today we are going to do a fingertip switch, use the human body resistance to light the led. Equipment Microduino-Core Microduino-FT232R Other hardware equipment Breadboard Jumper one box Breadboard one piece LED Light-emitting diodes one 10k,1k,220Ω resistor one 9014 triode one USB Data cable one Experimental schematic Human body resistance connects to VCC,and the other end connects the transistor's base. The principle is the same with principle diagram of lesson 12, so not in detailed again. Program void setup() { Serial.begin(115200); pinMode(13,OUTPUT); } void loop() { int n=analogRead(A0); //Read data from analog port if(n>0) //If the voltage changed,then run following program digitalWrite(13,HIGH); //Turn on the led else digitalWrite(13,LOW); //Turn off the led Serial.println(n);//Use seiral to monitor delay(100);//delay 100ms for refresh the data } Result Contact with human body resistance at both ends with the hand, LED light, once loose, the LED goes ff. You can try to do a touch switch? Video