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Vorhergehende Überarbeitung
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circuit_design:uebung_3.3.1 [2021/11/11 16:03]
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circuit_design:uebung_3.3.1 [2023/03/28 10:06] (aktuell)
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| <WRAP right><panel type="default"> <imgcaption pic3_3_1 | passive and active shielding> </imgcaption> {{drawio>pic3_3_1 }} </panel></WRAP> | <WRAP right><panel type="default"> <imgcaption pic3_3_1 | passive and active shielding> </imgcaption> {{drawio>pic3_3_1 }} </panel></WRAP> |
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| Imagine that you work in the company " HHN Mechatronics & Robotics", which is a cheap mobile [[https://de.wikipedia.org/wiki/Elektrokardiogramm|EKG]] – So I want to build a measuring device for the electrocardiogram or the cardiac voltage curve - for athletes and those in need. The measurement signal has only a few millivolts and microamps. In order to protect the signal from electromagnetic radiation on the way from the glued-on electrode to the evaluation electronics, a [[https://de.wikipedia.org/wiki/Abschirmung_(Elektrotechnik)#Elektromagnetische_Felder|Abschirmung]] placed around the line (see <imgref pic3_3_1>, above). However, since this creates a parasitic capacitor, a colleague suggested active shielding. The shielding is always kept at the measuring voltage that is applied to the line via a voltage follower (see <imgref pic3_3_1>, under). The parasitic capacitor is never charged due to this structure, since the same voltage prevails on both sides - there is no falsification of the signal. **It is important for the application that the voltage follower reacts quickly**. | Imagine that you work in the company "HHN Mechatronics & Robotics", which is a cheap mobile [[https://en.wikipedia.org/wiki/Electrocardiography|EKG]] – So you want to build a measuring device for the electrocardiogram or the cardiac voltage curve - for athletes and those in need. The measurement signal has only a few millivolts and microamps. In order to protect the signal from electromagnetic radiation on the way from the glued-on electrode to the evaluation electronics, a [[https://en.wikipedia.org/wiki/Electromagnetic_shielding|electromagnetic shielding]] placed around the line (see <imgref pic3_3_1>, above). However, since this creates a parasitic capacitor, a colleague suggested active shielding. The shielding is always kept at the measuring voltage that is applied to the line via a voltage follower (see <imgref pic3_3_1>, under). The parasitic capacitor is never charged due to this structure, since the same voltage prevails on both sides - there is no falsification of the signal. **It is important for the application that the voltage follower reacts quickly**. |
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| You are supervised with the design of this voltage follower and should use the available operational amplifiers $LM318$, $uA741$ and $uA776$analyze in the voltage follower circuit (see script page). | You are supervised with the design of this voltage follower and should use the available operational amplifiers $\rm LM318$, $\rm uA741$, and $\rm uA776$ analyze in the voltage follower circuit. |
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| Es ist ein kurzer Bericht (Problembeschreibung, Schaltung aus Tina, Ergebnisse, Diskussion) zu erstellen; als Analysewerkzeug ist Tina TI zu verwenden. | Write a short report (problem description, circuit in TINA TI, results, discussion) and use TINA TI for the solution. |
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| - Recreate the circuit described above for a realistic operational amplifier in Tina. Use a voltage generator as a source [[https://de.wikipedia.org/wiki/Heaviside-Funktion|Sprungfunktion]] („Unit step“) with the amplitude $U_A = 1,0 V$ . | - Recreate the circuit described above for a realistic operational amplifier in Tina. Use a voltage generator as a source [[https://en.wikipedia.org/wiki/Heaviside_step_function|unit step]] with the amplitude $U_\rm A = 1.0 ~\rm V$. |
| - Simulate over „Analysis“>>“Transient…“ the time course for the specified operational amplifiers. \\ Bestimmen Sie jeweils die Zeit die verstreicht bis der Ausgangswert von $0,1 V$ zum ersten mal $0,9 V$ erreicht (10% bis 90% der Amplitude, auch [[https://de.wikipedia.org/wiki/Anstiegs-_und_Abfallzeit|Anstiegszeit]] genannt). | - Simulate over ''Analysis''>>''Transient…'' the time course for the specified operational amplifiers. \\ Determine the time that elapses until the initial value of $0.1 ~\rm V$ for the first time $0.9 ~\rm V$ achieved ($10~\rm %$ to $90 ~\rm %$ of the amplitude, too. It is called [[https://en.wikipedia.org/wiki/Rise_time|rise time]]). |
| - Beschreiben Sie jeweils den Zeitverlauf. Gibt es neben der Anstiegszeit weitere Unterschiede? | - Describe the passage of time in each case. Are there any other differences besides the rise time? |
| - Welchen der drei Operationsverstärker würden Sie – auf Basis der angegebenen Informationen – für das Problem wählen? | - Based on the information provided, which of the three op amps would you choose for the problem? |
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| Vertiefende Informationen (nicht relevant für Hausarbeit): | In-depth information (not relevant to the exercise): |
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| * Masterarbeit zu [[https://www.uni-muenster.de/imperia/md/content/fachbereich_physik/technik_didaktik/entwicklung_und_bau_eines_demonstrationsmessg.pdf#page=42|Entwicklung und Bau eines Demonstrationsmessgeräts]] | |
| * Paper [[https://pdfs.semanticscholar.org/f2b9/2ee5f3e3adb034e18ddb85bd3770dc8c2c29.pdf|on the Stability of Shield-Driver Circuits]] | * Paper [[https://pdfs.semanticscholar.org/f2b9/2ee5f3e3adb034e18ddb85bd3770dc8c2c29.pdf|on the Stability of Shield-Driver Circuits]] |
| * Detaillierte Beschreibung einer [[https://www.elektronik-kompendium.de/public/schaerer/diffemg.htm|EMG/EKG Vorverstärkerschaltung]] | * Detailed description of a [[https://www.elektronik-kompendium.de/public/schaerer/diffemg.htm|EMG/EKG Vorverstärkerschaltung]] |
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