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--- university:courses:electronics:electronics-lab-window-comp-tmp01 [06 Mar 2018 17:57] – Antoniu Miclaus
+++ university:courses:electronics:electronics-lab-window-comp-tmp01 [07 Mar 2018 12:20] – add hardware setup and procedure Antoniu Miclaus
@@ Line 19: / Line 19: @@
 – 470Ω resistor\\
-===== Background =====
+===== Window Comparator =====
+==== Background ====
 Consider the circuit presented in Figure 1.
@@ Line 29: / Line 30: @@
 The circuit uses a voltage divider network, formed of three equal value resistors R1 = R2 = R3. The voltage drops across each resistor will also be equal at one-third of the reference voltage (V<sub>REF</sub>). Therefore, the upper reference (V<sub>REF(HIGH)</sub>) is set to 2/3V<sub>REF</sub> and the lower reference to 1/3V<sub>REF</sub>.
-Considering that we use the When V<sub>IN</sub> is below the lower voltage level, (V<sub>REF(LOW)</sub>) which equates to 1/3V<sub>REF</sub>, the inverted output will be HIGH (non-inverted output will be LOW) and D1 will be forward biased, driving the Q1 transistor. When V<sub>IN</sub> exceeds this 1/3V<sub>REF</sub> lower voltage level, the first comparator detects this and switches the inverted output to be LOW (non-inverted output HIGH).
+Considering that we use the When V<sub>IN</sub> is below the lower voltage level, (V<sub>REF(LOW)</sub>) which equates to 1/3V<sub>REF</sub>, the output will be HIGH and D2 will be forward biased. Due to the positive voltage at base the npn transistor, Q1 moves into the saturation. Thus, the output voltage is zero, and the supply voltage will drop on R5 and D3, turning the LED on.
+When V<sub>IN</sub> exceeds this 1/3V<sub>REF</sub> lower voltage level and it is below 2/3V<sub>REF</sub> (V<sub>REF(HIGH)</sub>), both comparators' outputs will be LOW and the diodes reverse-biased. No voltage is applied to the base of Q1,the transistor is in cut-off and no collector current flows through R6 or R5, D3. The output voltage is the supply voltage V+.
+When V<sub>IN</sub> is above the upper voltage level, (V<sub>REF(HIGH)</sub>) which equates to 2/3V<sub>REF</sub>, the output will be HIGH and D1 will be forward biased. Due to the positive voltage at base the npn transistor, Q1 moves into the saturation. Thus, the output voltage is zero, and the supply voltage will drop on R5 and D3, turning the LED on.
+==== Hardware Setup ====
+Build the following breadboard circuit for the window comparator circuit.
+<WRAP centeralign>{{:university:courses:electronics:window_comp-bb.png|}}</WRAP>
+<WRAP centeralign> Figure 2. Window Comparator breadboard circuit </WRAP>
+==== Procedure ====
+Use the first waveform generator (W1) as source to provide a Triangular signal with 5V amplitude, 100Hz frequency and 2.5V offset.
+Use the second waveform generator (W2) as 5V constant reference voltage.
+Supply the circuit using the 5V power supply.
+Configure the scope so that output signal is displayed on channel 2 and the input signal is displayed on channel 1.
+A plot example is presented in Figure 3.
+<WRAP centeralign>{{:university:courses:electronics:window_comp-wav.png|}}</WRAP>
+<WRAP centeralign> Figure 3. Window Comparator waveforms </WRAP>
+ On the plot the "windows" can be noticed when the input voltage is between the upper and the lower voltage references.

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