# ANALISIS RANGKAIAN SENSOR Cahaya (LDR) dan LED English :

After seeing the picture above, There are several issues that need to be Answered:
1. Why PARALLEL LDR linked with R2?
2. Why LDR is under R2?
3. What is the relationship between R2 and R3?

OK >>> I will try to answer the above issue …. 🙂

Problems I: current LDR linked parallel with R2 it will form a series of transistors as switches. As we know, the voltage drop across the LDR is equal to VBE (approximately 0.7 V = voltage drop across the diode).
when exposed to light the LDR LDR R will be LOW, Mis, 0 ohms (resistance I anticipated when light LIGHT), then: Vldr = (0) * 6y / (0 +11) = 0 V. Thus, in these circumstances, the transistors in the open state = LED is off.
LDR when exposed to dim light at LDR then R will be INCREASED, eg, 51 ohm (approximate). then: Vldr = ((51) * 6y) / (51 +11) = 4.93 V, so that the transistors will be closed = LED Lighted.
Second problem: the voltage drop due to current, determining LDR TRANSISTOR be OPEN or CLOSED.
If the position is exchanged LDR R2, the voltage drop across R2 that will determine the conditions Transistor (Open or Closed). because R2 is worth FIXED, FIXED then fall voltage also (LDR effect is very small) so that the transistors maintaining the condition corresponding voltage drop across R2.
Problem III: R2 serves as the components that make up the circuit transisitor as a switch with LDR component.
R3 serves to protect the diode from excessive current and VOLTAGE that can damage the diode.

Indonesian :

Setelah melihat gambar di atas, Ada beberapa masalah yang perlu Dijawab :
1. Mengapa LDR dihubungPARALELkan dengan R2?
2. Mengapa LDR berada di bawah R2?
3. Apa hubungan antara R2 dan R3?

OK>>>Saya akan mencoba menjawab Masalah di atas….:)