Available online
Description
The programme is concerned with the idea of frequency response in terms of how it is measured and its underlying theoretical origin.
The programme is concerned with the idea of frequency response in terms of how it is measured and its underlying theoretical origin.
| Module code and title: | T283, Introductory electronics |
|---|---|
| Item code: | T283; 02 |
| First transmission date: | 09-04-1980 |
| Published: | 1980 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:22:25 |
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| Producer: | Tony Jolly |
| Contributors: | David Crecraft; Glyn Martin |
| Publisher: | BBC Open University |
| Keyword(s): | Electronics; Frequency response |
| Footage description: | Shots of a signal generator circuit and its associated oscilloscope trace. David Crecraft introduces the programme. He displays sine waves of various amplitudes and frequencies and then adds two sine waves together. Crecraft next shifts the phase of one of the input waves and notes the result of the addition. Glyn Martin puts various wave forms through linear circuit to demonstrate that sine waves are the only test signals which retain their shape in all linear circuits. David Crecraft briefly demonstrates the home kit generatorscope; an oscilloscope sent to students. Crecraft works through an experiment on frequency response which students were asked to do on their generatorscopes at home. Glyn Martin uses a commercial swept frequency generator to compare the input and output frequencies of sine waves. The apparatus measures the amplitude and phase shift produced. He goes on to repeat the experiment this time using the amplifier from the student home experiment kit. Martin tries a different experiment using the same equipment. He connects the output of the amplifier to the input of the low pass circuit. David Crecraft examines still photographs of the oscilloscope traces obtained in the above experiments. He shows that when the circuits are cascaded their amplitude ratios multiply together. Crecraft goes on to show, by examining several phase plots, that when these circuits are cascaded together, their phase shifts add together. Glyn Martin explains another method, that of using phasor operators, for predicting how two circuits behave in cascade. He manipulates phasor diagrams as he talks. David Crecraft, with the aid of phasor diagrams, explains how, by using such diagrams, one can predict the amplitude of two out of phase sinewaves added together. |
| Master spool number: | OU 3379 |
| Production number: | FOUT052L |
| Videofinder number: | 2651 |
| Available to public: | no |
