Elenco Electronics EP-130, Руководство пользователя

Страница: 132 / 160

This is a two-transistor receiver with enough gain
(amplification) to allow you to hear the signal
through the speaker. Simple radios like this one
require a good antenna and ground system.
Connect the circuit and use terminal 74 as the
ground terminal. Connect the antenna to terminal 95
or 97. Use the one that provides the best results.
The radio’s detector circuit uses a diode and a 22k
Ω
resistor. Try to use the radio without the 22k
Ω
resistor. Simply disconnect the wire from terminal
85. The results are ________ (worse / improved) for
weak stations and ________ (worse / improved) for
strong stations.
The basic rules of radio reception are the same as
in Project 110 (“Crystal Set Radio (Simple-Diode
Radio)”). The tuning capacitor selects the radio
station frequency. The diode and 0.02
μ
F capacitor
rectify (detect) the audio signal, changing it from AC
to DC. This signal is so weak that we must amplify it
to be able to hear it through the speaker. Transistor
Q1 amplifies the signal first, then the control adjusts
the volume, and finally Q2 amplifies the signal
again. Finally, the speaker produces the amplified
sounds.
Notes:
EXPERIMENT #111: TWO-TRANSISTOR RADIO
-132-
Wiring Sequence:
o
1-29
o
2-30
o
3-44
o
5-72-131
o
6-12-96
o
7-98-126
o
8-11-74-86-88-104-115-117-42-119
o
71-82-116-26
o
27-113
o
28-43-87
o
40-112-91
o
81-92-114-41
o
45-118-73
o
85-103-111-125
o
121-122
o
124-132
o
95-ANT (or 97-ANT)
Schematic