 PIC16F84A
This PIC analyzes the control code to take
from the transmitter and when receiving a normally code, it controls a
relay.
Low noise operational amplifier ( LM358
)
The voltage of the signal which
detected a high frequency isn't enough for PIC. The input voltage which
PIC needs is made by amplifying by this amplifier. The operation is
similar to the comparator. The output becomes an open condition when the
input voltage of the positive terminal exceeds the voltage of the negative
terminal. For the mounting space, I used the operational amplifier of the
8 pin type.
FET for the high frequency amplification (
2SK439 )
This transistor is used to amplify a
received electric wave.
Transistor for relay drive ( 2SC1815
)
This transister is used to drive the
relay.
3 terminal regulator ( 78L05 )
3 terminal regulator is used to make
the power (+5V) of PIC from +12V power.
A 100mA
type is used.
IC socket
These are 18 pins socket for
PIC16F84A and 8 pins socket for LM358.
I used a
round hole type for PIC but you can use a board type, too.
Resonator
This is the oscillation device to
make the clock of PIC. A ceramic vibrator and capacitors are
incorporated.
The clock frequency this time is 4
MHz. It is possible to make do the operation of PIC16F84A with the a
maximum of 20MHz clock.
High frequency transformer
This transformer is made to resonate
with the frequency of the transmitter. With it, only the electric wave of
the transmitter can be received. The transformer which was used this time
is the type which is called 7S80 for about 80 MHz. The size is 7
mm.
The specification when you make a coil is
hereinafter.
 |
The coil on the side of the resonance is
6 turns with center tap.
The coil on the side
of the output is two turns.
|
Diode for the detection ( 1N60
)
A diode for the high frequency is used for a
detection diode, because it rectifies an about 80-MHz high frequency
directly.
I used a Germanium
diode.
Zener diode ( RD5A )
When not using this diode, the
change range of the output of LM358 is 0V-12V.
The
maximum voltage of the I/O port of PIC is 5V. Because it is, the voltage
which is applied to PIC is controlled to 5V by this
diode.
Output relay ( G5V-1 )
This is the small relay which is
made by the OMRON Inc..
 |
| Drive voltage |
DC 12V |
| Number of contacts |
1 |
| Contact capacity |
30VDC |
1.0A |
| 125VAC |
0.5A |
| 80VDC |
0.3A | |
Light Emitting Diode
The equipment this time is using two
control codes.
I used LEDs with different color as
the understanding of control code.
Red is used for
circuit 1 and green is used for circuit 2.
Brightness type is used.
Transistor protection diode ( 1S1588
)
This diode is used to prevent from
transistor destruction by the back electromotive force of the relay.
Resistor
At the circuit this time,
the resistors with 1/8 W permission electric power are
used.
Ceramic capacitor
Ceramic capacitors with good high
frequency characteristic are used for the resonance circuit.
Multilayer ceramic
capacitor
The unnecessary high frequency which
influences circuit operation is bypassed with these
capacitors.
This capacitor has a large capacity
comparatively with 10000pF but it is small.
Printed board
I used the boad with 15 holes x 25
holes.
Ground board
The circuit this time handles a high
frequency. To ground surely, I put a brass board with 0.5-mm thickness
under the printed board.
Wiring terminal
This terminal is used for the wiring
with the outside parts such as the power supply, the antenna and the
output of the relay.
Stud
This stud is used to fix a
printed board on the case.
Antenna terminal
This is the terminal to connect the
outside antenna.
Output terminal
This is the terminal to connect
circuits on the outside to correspond to the control code.
AC adapter
This is the power supply
adapter to get DC +12V from AC 100V. The 300-mA electric current can be
passed.
Power supply connector
This is the connector to connect the
AC adapter.
Case
I housed a receiver in the case
which was made by bending acrylic board.
Back panel
I put
the panel which wrote the name at the back. It is the one which was
printed in the color to the OHP sheet. I put in the white paper for the
letter be able to be clearly seen.
Leg
This is the leg to have
put to the part in the bottom.
These legs are to
protect the case when putting the measurement equipment.
Terminal cover
This is the cover which
protects the connection part of the wiring.
Because
the connection part is the circuit inside, it isn't touched. I used
because I looked pleasant
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