This simple lamp dimmer uses only a Triac, a Diac and some other passive components to achieve power control on lamp . It is suitable for 230V incandescent lamps with a total power of up to 300 Watts. At first triac TR1 is not conducting; C1 is charged through R1/P1 until the trigger level of diac D1 is reached. When the diac trigger level is reached (about 30 V), D1 fires and Triac TR1 is switched on. The triac will remain in conductive mode until the mains current is lower than the triac hold current at the end of the half mains period. This works for both the negative and positive mains period because both the triac and the diac are bi-directional. R1 is added to protect the potentiometer in the case of a short circuit. The fuse is absolutely mandatory as the discharge arc in a failing incandescent lamp is virtually a short circuit.
Posted on Wednesday, March 23, 2011 • Category: USB Circuts
Sometimes you just need to connect some device to COM port, but computer don’t have one especially laptop. There are two ways â€“ go and buy USB â€“ COM adapter or build one. So if you decided to build USB to COM(RS232) adapter, there is one of solutions.
This adapter is very easy to build as there is single chip USB to UART bridge (CP2102) used. This chip from Silicon Labs support USB2.0 full speed, has internal Resistors required for USB interface, integrated clock, internal 1024 -byte EEPROM for vendor ID, Product ID serial number, power descriptor and other information. SP2102 USART part support almost all standard features of RS232 communication including handshaking, Databits (5, 6, 7 and 8); 1 or 2 stop bits; odd, even, mark, space and no parities; baud rate from 300bps to 1Mbits.
Device is powered from USB port and requires about 10mA. Chip drivers enable to connect this adapter to most of Operation systems like Win98, Win2000, WinXP, Linux.
Posted on Tuesday, March 22, 2011 • Category: USB Circuts
USB switch is used to share USB devices such as printers, scanners, hard drivers, etc. between two computers. Just connect the two computers on a network device and say the printer as shared. This method however requires the continued operation of the computer we plugged the printer. Solution to above problem is to give the circuit that we present, and has the potential to be transferred to the printer on whichever computer we want, because the printer is connected to one of two computers, but in construction.
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