Example Transistor Driver Circuits Lo Side Drive (NPN) Load La1 is connected to the +V supply (Hi) and then switched to ground (Lo) to turn on. (Positive Logic – High on the input turns the load on.) See far upper right example. Hi Side Drive (PNP) Load La2 is connected to ground (Lo) and then switched to +V (Hi) to turn on. (Negative Logic – Lo on the input turns the load on.) Lo side driver relay driver Darlington pair transistors are used in applications where Very heavy current loads need to be controlled. The darlington Configuration offers much higher current gain because the hfe of the device is the product of the hfe of the two transistors TR1 and TR2. Opto-Isolators offer isolation which is not easily obtainable with any other device. When controlling very high voltages this provides Isolation protection for sensitive devices such as micro-controllers.
AC Plug and Wiring Color code World Region, country or other entity(ies) Line or Live (Hot)NeutralProtective earth/ground United States and Canadablack (brass)white (silver) green (green) or bare copper wire EU,Australia & South Africa (IEC 60446) brownbluegreen & yellow Australia & New Zealand (AS/NZS 3000:2000 3.8.1) redblackgreen/yellow Note: 1. The (Brass) and (Silver) references above denote the screw colors used on most electrical fixtures. (Switches, Outlets, etc) 2. For Multi Phase Applications color codes defer between systems. Refer to manufacturer or country standards for the appropriate colors. DC Wiring Color Code Wire insulation Color Common Power Supply or Function Description Black0VGround or Common Yellow+5VLogic Supply Red+12V or +15VAnalog Supply Blue-12V or -15VAnalog Supply Orange+24VControl Supply Note: 1. The above colors are those established by the ME E-Shop and are used here for reference. You can establish your own wiring color standard although it is suggested that you maintain BLACK as your Ground or Common color.