Solid State Shortwave Receivers For Beginners - The Listeners Guide
Solid State Shortwave Receivers For Beginners - The Listeners Guide
Solid State Shortwave Receivers For Beginners - The Listeners Guide
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Components List for Fig.22<br />
Resistors (¼ Watt 5%).<br />
R1 220k.<br />
R2 10 Meg.<br />
R3 10 Meg.<br />
Capacitors.<br />
Cl 10nf plastic foil.<br />
C2 10nf plastic foil.<br />
C3 100mfd. 10v.w.<br />
C4 10nf ceramic.<br />
C5 10nf plastic foil.<br />
VC1 50pf air spaced (type C804).<br />
VC2 365pf air spaced (type 0).<br />
Semiconductor.<br />
I.C. CD4001AE.<br />
Inductors.<br />
T1 Denco Green D.P. coils Ranges 3, 4, and 5.<br />
L1 10mH. (Repanco CH4).<br />
Miscellaneous.<br />
S1 S.P.S.T. toggle switch.<br />
Chassis, panel, sockets, connecting wire, etc.<br />
Regeneration is provided from the output by way of a winding<br />
on T1 and variable capacitor VC1. <strong>The</strong> latter acts as the reaction<br />
control. Although the gate is said to be biased as a linear amplifier,<br />
like any practical amplifier it has some degree of distortion, and by<br />
applying regeneration it performs very well as an regenerative detector.<br />
<strong>The</strong> output of the first amplifier is coupled by C2 to the R.F.<br />
filter which comprises L1 and C4. From here the signal is coupled to<br />
a second amplifier by C5. This is used as an audio amplifier and is<br />
biased by R2 and R3. Two resistors in series are used here as a single<br />
resistor having a suitably high value is not readily obtainable. A high<br />
value is not required here in order to provide a really high input<br />
impedance, but to provide a high level of voltage gain. Using a high<br />
value bias resistor reduces the amount of negative feedback that is<br />
applied to the circuit, and so gives a higher level of voltage gain.<br />
<strong>The</strong> output of the audio amplifier is directly coupled to SK3,<br />
and this can be used to feed a crystal earpiece or a pair of crystal headphones.<br />
Other types of headphone are not suitable.<br />
Only one supply decoupling component is required, and this is C3.<br />
VC2 the usual tuning control and S1 is the on off switch.<br />
CMOS devices have extremely low current consumptions, and<br />
this receiver draws only about 1 mA. from a 9 volt supply. <strong>The</strong> circuit<br />
does not have to be used with a 9 volt battery, and will work satisfactory<br />
with any supply potential of between 4.5 and 15 volts.<br />
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