This simple 220V light dimmer circuit can be used to adjust the brightness of mains lights. It also can be used to adjust the speed of AC motors. It uses a triac, diac and has a radio-frequency interference (RFI) noise suppression circuit built into it as well.

Schematic diagram:

Component part:
R1 = 10K
R2 = 2K2
R3 = 180K
Potentiometer 250K
C1 = 150nF/400V dipped polyester
C2 = 47nF/630V  dipped polyester
C3 = 220nF/250V AC dipped polyester
Triac = 2N6075 or BT136-500D
Diac = HT-32
FUSE 2A or 3A

This is a 220V LED flasher circuit which is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. This a cheap circuit and easy to build.

Schematic diagram:

Component Parts:

R1_________ 100K
R2,R5______ 1K
R3,R6______ 470R
R4_________ 12K
C1_________ 1000µF 25V
D1-D4______ 1N4007
D5_________ SCR  P0102D
Q1_________ BC327
Q2_________ BC337
SK1________ Female Mains socket

Following is a circuit you can use to delay an electronic device to be disabled. For example, you can connect this circuit to the lamp in your room. When you turn off the lamp with a switch on the circuit, the lamp will remain lit in a certain period of time, before the lamp really switched off.

Electronic Parts: