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Parts explanation of Decorative light Controller


PIC16F628 is used in this circuit. The pin assignment of PIC16F628 is almost same as PIC16F84A. PIC16F628 are equipped with many functions rather than 84A. Such as voltage comparison function, CCP function, communication function, etc. The reason I chose 628 is it's memory capacity. PIC16F628 has 2K words program memory.

Decoder (74HC138)

This is the IC which decodes the binary code of 3 bits.
It is used to check the condition of the BCD switch which chooses a lighting-up pattern.

IC socket

IC sockets are used to mount PIC16F84A and 74HC138.
Because it is necessary to rewrite software while debugging, a socket should be used for PIC.
TRIAC ( SM12J45 )

A TRIAC is used for the control of the AC voltage. The TRIAC which is used this time is the type which can control the AC current of 12A.

The installation part of the TRIAC is connected with the MT2 terminal. So, it is necessary to use a insulation sheet when installing in the case.
Photo-Triac ( TLP560 )

This is a device to drive a triac.
This device is used for carrying out insulation of a circuit, separation of an alternating current circuit and a direct current circuit, and high-speed operation. A zero voltage crossing type cannot be used.

Photo Coupler ( TLP626 )

This device is used to detect 0V of AC voltage.
This device is used for insulation of a circuit, separation of AC/DC circuit, and high-speed operation like Photo-Triac.

3 terminal regulator ( 7805 )

This device is used to make +5V which is the power of PIC and the decoder. Since Photo-Triac is driven, 1A type is used.


This is the 4MHz resobator.
There is an internal oscillator of 4MHz in PIC16F628. When using it, to put an oscillation element outside isn't necessary. Because I got to know the built-in oscillator after the end of circuitry, I am using the external oscillation element as it is.

PNP transistor ( 2SA1015 )

This transistor is used for the selecting circuit of the BCD switch.

BCD Switch

BCD switch is used to select LED lighting-up pattern. At this circuit, a printed circuit board mounting type is used.

Switching diode (1SS1588 )

This diode is used for the countercurrent prevention with the BCD switch circuit.

Power transformer

This is a small transformer which input is 100VAC and the output is 6VAC with center tap.

Rectification diode

This is the diode to rectify AC to DC.
I use 100V and 1A type.

Film capacitor

By the switching operation of the triac, the extraordinary voltage sometimes occurs to the load. This capacitor is used for the snubber circuit to absorb it.
Its WV is 400V and the capacitance is 0.1F. Non polarity type is required.

Electrolytic Capacitor

10F/16V is used for the ripple filter.
2200F/10V is used for the stability of 5V.

Multilayer Ceramic Capacitor

This capacitor is used in order to suppress the oscillation of 3 terminal regulator.


The small resistor of 1/6W is used for the +5V circuit. And 1/4W is used for the AC circuit.

Printed circuit board P

The universal printed circuit board with 24 x 30 holes is used for the control board.

Printed circuit board Q

The universal printed circuit board with 15 x 25 holes is used for the triac drive circuit.


This metal stud is used to fix a printed circuit board on the case.
The metal stud is used in order to ground.


The pin type terminal is used for wiring to the printed circuit board.

Lug terminal

This lug terminal is used to connect the stud to the ground.

Terminal cover

This cover is used in order to prevent terminal contact of TRIAC.


I use the case made by TAKACHI.
The model is YM-180.
180mm(W), 40mm(H), 130mm(D)
It made from aluminum.

Output plug socket

This is an output plug socket for connecting load.

Power cable

This equipment has the control circuit of 5 circuits. I assume the control of 1000W in amount.
So, 12A type is used for the power cable.
A Parts like a bolt is the cable protector which prevent the crack by case.


I use a 10A fuse.
When using continuously at 1000W, the fuse with big permission value must be used.

Power Switch

This switch is used for Power OFF/ON.
The specification of a contact is
15A 125V AC
10A 250V AC

Pilot Lamp

This lamp is used to check the condition of a power supply.
Lug terminal

This lug terminal is used for wiring of AC cable.
Resistor network

This is used for the pull-up of TR 1-5. Five resistors are built in and one end is connected inside. The connection is connected to the 6th pin.
Thumbwheel switch

This switch is used in order to change the blink pattern of each circuit.
The switch used this time is a type called SDG9000 made by FUJISOKU Co.