no way to compare when less than two revisions

Differences

This shows you the differences between two versions of the page.

@@ Line 1: / Line 1: @@
+====== Activity: Temperature Control using Window Comparator ======
+===== Objective =====
+The objective of this lab activity is to use two high speed voltage comparators as a Window-Comparator and program the [[http://www.analog.com/media/en/technical-documentation/data-sheets/TMP01.pdf|TMP01]] Low Power Programmable Temperature Controller using this approach.
+A Window-Comparator is a circuit configuration, usually consisting of a pair of voltage comparators (inverting and non-inverting), in which the output indicates whether an input signal is within the voltage range bounded by two different thresholds. One which triggers an op-amp comparator on detection of some upper voltage threshold, V<sub>REF(HIGH)</sub> and one which triggers an op-amp comparator on detection of a lower voltage threshold level, V<sub>REF(LOW)</sub>. The voltage levels between these two upper and lower reference voltages is called the “window”.
+===== Materials =====
+ADALM2000 Active Learning Module\\
+Solder-less breadboard, and jumper wire kit\\
+– AD8561 Comparators\\
+– 2N3904 NPN transistor\\
+– 1N914 small signal diodes\\
+– LED ( any color )\\
+– 10KΩ resistor\\
+– 20KΩ resistor\\
+– 470Ω resistor\\
+===== Window Comparator =====
+==== Background ====
+Consider the circuit presented in Figure 1.
+<WRAP centeralign>{{:university:courses:electronics:window_comp-sch.png|}}</WRAP>
+<WRAP centeralign> Figure 1 Window Comparator </WRAP>
+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 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.

Wiki

Analog Devices Wiki

Differences

Analog Devices Wiki

Differences

Page Tools