File:Marconi crystal radio receiver.jpg
Summary
Marconi type 103 <a href="https://en.wikipedia.org/wiki/crystal_radio" class="extiw" title="wikipedia:crystal radio">crystal radio</a> receiver, used with the Marconi company's spark transmitter systems during the pioneering <a href="https://en.wikipedia.org/wiki/wireless_telegraphy" class="extiw" title="wikipedia:wireless telegraphy">wireless telegraphy</a> era of radio around 1920. The <a href="https://en.wikipedia.org/wiki/cat%27s_whisker_detector" class="extiw" title="wikipedia:cat's whisker detector">cat's whisker detector</a> is visible at top. This radio used an inductively-coupled antenna transformer circuit, which improved the selectivity (Q factor) of the receiver, allowing interfering stations near the desired station to be rejected. The "short wave condenser" tuned the primary coil, the "intermediate condenser" tuned the secondary. The "aerial tuning inductance" knob selected taps on the coil winding to adjust the <a href="https://en.wikipedia.org/wiki/impedance_matching" class="extiw" title="wikipedia:impedance matching">impedance match</a> between the antenna and the receiver. The "Billi condenser" was a decoupling capacitor across the earphone leads, which smoothed the audio signal from the detector, removing the residual RF carrier pulses. The "potentiometer" applied an adjustable bias voltage from a battery across the detector, to make it more sensitive.
Licensing
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 16:16, 13 January 2017 | | 754 × 552 (74 KB) | 127.0.0.1 (talk) | Marconi type 103 <a href="https://en.wikipedia.org/wiki/crystal_radio" class="extiw" title="wikipedia:crystal radio">crystal radio</a> receiver, used with the Marconi company's spark transmitter systems during the pioneering <a href="https://en.wikipedia.org/wiki/wireless_telegraphy" class="extiw" title="wikipedia:wireless telegraphy">wireless telegraphy</a> era of radio around 1920. The <a href="https://en.wikipedia.org/wiki/cat%27s_whisker_detector" class="extiw" title="wikipedia:cat's whisker detector">cat's whisker detector</a> is visible at top. This radio used an inductively-coupled antenna transformer circuit, which improved the selectivity (Q factor) of the receiver, allowing interfering stations near the desired station to be rejected. The "short wave condenser" tuned the primary coil, the "intermediate condenser" tuned the secondary. The "aerial tuning inductance" knob selected taps on the coil winding to adjust the <a href="https://en.wikipedia.org/wiki/impedance_matching" class="extiw" title="wikipedia:impedance matching">impedance match</a> between the antenna and the receiver. The "Billi condenser" was a decoupling capacitor across the earphone leads, which smoothed the audio signal from the detector, removing the residual RF carrier pulses. The "potentiometer" applied an adjustable bias voltage from a battery across the detector, to make it more sensitive. |
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