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Build a 65W Notebook Laptop Power Adapter

Using TOP269EG off-line switcher IC, (U1), in a flyback configuration can be designed a very simple high efficiency notebok laptop power adapter.TOP269EG IC has an integrated 725 V MOSFET and a multi-mode controller. It regulates the output by adjusting the MOSFET duty cycle, based on the current fed into its CONTROL pin.This laptop power adapter circuit will provide a fixed 19 volts output voltage at a maximum current of 3.5A. input voltage range is between 90 to 265VAC. Common-mode inductors L3 and L4 provide filtering on the AC input. X class capacitor C1 provides differential filtering, and resistors R1 and R2 provide safety from shock if the AC is removed, by ensuring a path for C1 to discharge. This is required by safety agencies when the capacitor value exceeds 100 nF. Bridge rectifier D1 rectifies the AC input, and bulk capacitor C2 filters the DC.

VGA to BNC Adapter Converter Circuit Diagram

This is the VGA to BNC Adapter Converter Circuit Diagram. There are monitors which only have three BNC inputs and which use composite synchronization (‘sync on green’). This circuit has been designed with these types of monitor in mind. As can be seen, the circuit has been kept very simple, but it still gives a reasonable performance. The principle of operation is very straightforward. The RGB signals from the VGA connector are fed to three BNC connectors via AC-coupling capacitors. These have been added to stop any direct current from entering the VGA card. A pull-up resistor on the green output provides a DC offset, while a transistor (a BS170 MOSFET) can switch this output to ground. It is possible to get synchronisation problems when the display is extremely bright, with a maximum green component. In this case the value of R2 should be reduced a little, but this has the side effect that the brightness noticeably decreases and the load on the graphics card increases. To keep the col...

Adapter power supply and charger circuit

Basically adapter, power supply and charger circuit has a similar construction which consists of a transformer, rectifier (rectifier) and smoothing the voltage. For there is usually an additional power supply voltage stabilizer of voltage regulator IC LM series 78XX or 79XX . Below is a schematic circuit adapter, power supply, or battery charger (for gadgets, mobile phones, MP4player, smartphone) that is equipped with a 5V voltage stabilizer: Adapter, power supply and charger circuit