PIC16F873
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The output of a temperature sensor is analog voltage. Therefore, conversion to a digital signal is required using an A/D converter. With this equipment, PIC16F873 with a built-in A/D converter is used.
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Temperature sensor ( LM35DZ )
LM35 series of National Semiconductor is used. It is D type which was used this time, and it can be measured from 0°C to +100°C. The output of a sensor is set to 0V at 2°C, and +10mV/°C is outputted.
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Operational amplifier ( LM358 )
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This operational amplifier can operate with a a single power supply.
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PNP transistor ( 2SA1015 )
This transistor is used for the scan of LED and BCD-SW. Since LED is a common anode type, a PNP type is used.
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NPN transistor ( 2SC1815 )
This transistor is used for the drive of the relay for external device control.
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Positive Voltage Regulator ( 7805 )
This is a regulator for +5V output. Since LED is made to turn on by +5V, 1A type is used.
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Sensor cover
The cover of a mini jack is used for the sensor cover. I did not use the portion of the pin of a jack but used only the case. LM35DZ is shown under the cover. |
BCD-SW ( RDS610 )
This is a DIP Rotary Code Switch made by SAGAMI. The BCD code is outputted.
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IC socket
Since PIC16F873 are removed when rewriting a program, its IC socket is indispensable. 873 is 28 pins slim type DIP, so it can use two IC sockets for 14 pins. |
Switching diode ( 1S1588 )
This is a switching diode. These switching diodes are used for adverse current prevention of BCD-SW, and used for control of the back electromotive force generated in a relay.
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Ceramic resonator
This is a ceramic resonator for 4MHz.
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7 segment LED for a current temperature
The size is 12mm in width, 18.8mm in height and 8mm in depth.
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7 segment LED for a preset temperature
The size is 7mm in width, 11mm in height and 5mm in depth.
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Slide switch
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This switch is used for the control mode change. Below preset temperature or above. |
Control circuit drive display LED
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This is LED which displays the drive state of a control circuit. Green is for circuit 1 and an orange is for circuit 2. |
Relay ( G6C-2117P-US )
This is a relay which drive the external circuit. It is made by OMRON. Since there is polarity in this relay at a drive coil, it will not operate, if it connects conversely.The specification of a point of contact is shown below.
250VAC : 8A / 30VDC : 8A |
Resistor
1/6W type is used altogether. |
Potentiometer
This potentiometer is used for adjusting the gain of an OP amplifier. This is 25 rotation type.
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15 rotation type |
Rectification diode bridge
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100V-1A diode bridge is used for rectification. |
Electrolytic capacitor
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This capacitor is used for the filter of a power supply. |
Multilayer ceramic capacitor
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This capacitor is used for oscillation prevention of a regulator. |
Printed circuit board
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This printed circuit board has 27 x 36 holes. However, part mounting cannot be performed near the corner. |
Stud
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This is the parts for attaching a printed circuit board in a case. |
Transformer
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This is the small transformer which secondary side output is 10V-300mA. |
Output socket
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This is a socket which connects an external circuit ( ventilation fan ). |
Case
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The size is 150mm in width, 54mm in height and 170mm in depth. |
Fuse
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This is the small fuse of 1A. |
Sensor connection plug
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This is the mini jack of the stereotype used with audiovisual apparatus. |
Shielded cable
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This is the cable which connects a temperature sensor and a control part. |
AC cable / protector
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This is the AC code of 700W type.
A protector is used in order to prevent the crack by the case. |
Acrylics board ( purple )
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This is the purple acrylics board used for the front of LED. The display of LED becomes clear with this acrylics board. |
Character seal
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This is the character seal used for the name display of a panel. |
Terminal
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This is a terminal for changing a display to test mode. Red part is the short pin for short-circuiting terminals. |
Test pin
This is the test pin attached to the checkpoint of a circuit. Since the tip is a ring, connection of a hook chip etc. is easy. |
Terminal
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This is a terminal for connecting a power cable. |
Heat sink
Many heat occurs in a regulator. Heat sink was not attached at the beginning. But, since it got as hot as it cannot touch, heat sink was attached. |
Tantalum Capacitor
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This capacitor is used in order to stabilize the output voltage of a temperature sensor. |