Why is a high impedance earphone better for a crystal radio?
thanks
thanks
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Another way to look at it is that the Crystal set captures very little power and can, therefore, supply very little current. With the proper design, it can, however deliver considerable voltage.
A high impedance earphone (such as a crystal earphone) requires some voltage, but requires very little current. This is a good "match" for the crystal set's capability.
A high impedance earphone (such as a crystal earphone) requires some voltage, but requires very little current. This is a good "match" for the crystal set's capability.
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The LC tuning circuit has a high impedance at resonance. Connecting anything across it lowers the 'Q' and therefore the selectivity, the lower the impedance connected across it, the worse the effect.
Additionally, a low impedance load across a high impedance source inevitably drastically reduces the available signal.
Additionally, a low impedance load across a high impedance source inevitably drastically reduces the available signal.
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The signal coming out of a crystal radio is very weak, it's just the power of the radio waves themselves. The headphone converts this weak signal to sound waves, and a higher impedance headphone does this more efficiently, making the most of what little signal is there.
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Because output from crystal detector has very high impedance,low impedance earphone overload the circuit and ends up very little signal. Besides,high input impedance earphone has very high sensitivity.
It can detect 10mv signal strength whereas a 8 ohm earphone requires at least 100mv.
It can detect 10mv signal strength whereas a 8 ohm earphone requires at least 100mv.