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| university:courses:electronics:electronics-lab-22 [05 Mar 2019 12:33] – [Questions:] Antoniu Miclaus | university:courses:electronics:electronics-lab-22 [12 Jul 2019 14:07] – Pop Andreea | ||
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| - | ====== Activity | + | ====== Activity: Optocouplers. ====== |
| ===== Objective: ===== | ===== Objective: ===== | ||
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| In this activity you will construct an optocoupler from an infra-red LED and an NPN photo transistor. You will investigate the operation of an optocoupler based analog isolation amplifier and floating current source using integrated optocouplers. | In this activity you will construct an optocoupler from an infra-red LED and an NPN photo transistor. You will investigate the operation of an optocoupler based analog isolation amplifier and floating current source using integrated optocouplers. | ||
| - | ===== 22.1 The NPN transistor Optocoupler ===== | + | ===== The NPN transistor Optocoupler ===== |
| ==== Background: ==== | ==== Background: ==== | ||
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| Open the frequency display within the scope window. Adjust the time base such that the fundamental and the first 5 or 6 harmonics are displayed. Write down and save the magnitudes of the fundamental and up to at least the 4< | Open the frequency display within the scope window. Adjust the time base such that the fundamental and the first 5 or 6 harmonics are displayed. Write down and save the magnitudes of the fundamental and up to at least the 4< | ||
| - | ===== 22.2 Driving the LED with a voltage to current converter ===== | + | ===== Driving the LED with a voltage to current converter ===== |
| By putting the LED in the feedback loop of an op amp configured as a voltage to current converter we can greatly reduce the effect of the nonlinearity of the LED. | By putting the LED in the feedback loop of an op amp configured as a voltage to current converter we can greatly reduce the effect of the nonlinearity of the LED. | ||
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| Compare your distortion measurements for this circuit to what you measured for the previous circuit. How much have the harmonics improved? | Compare your distortion measurements for this circuit to what you measured for the previous circuit. How much have the harmonics improved? | ||
| - | ===== 22.3 Analog Isolation amplifier. ===== | + | ===== Analog Isolation amplifier. ===== |
| To make a more linear amplifier two matching optocouplers can be used. It is best to use integrated versions for this circuit. | To make a more linear amplifier two matching optocouplers can be used. It is best to use integrated versions for this circuit. | ||
university/courses/electronics/electronics-lab-22.txt · Last modified: 04 Nov 2022 19:26 by Doug Mercer