This is the USB Power Booster circuit diagram. The USB serial bus could be configured for connecting various peripheral / electronic devices to a single personal computer. It can be much more complicated than RS232, but quicker and simpler for PC expansion.
Considering that a PC can supply only a limited power towards the external devices connected via its USB port, when a lot of devices are connected simultaneously, there’s a possibility of power lack. For that reason an external power source needs to be added to power the external devices.
In USB, two various types of connectors are utilized: model A and model B. The circuit provided here is an addon unit, intended to add extra power to a USB supply line (type-A). When power signal from the PC (+5V) is received via socket A, LED1 glows, opto-diac IC1 conducts and TRIAC1 is triggered, resulting in availability of mains supply from the primary of transformer X1. Now transformer X1
delivers 12V at its secondary, that is rectified by a bridge rectifier comprising diodes D1 via D4 and filtered by capacitor C2.
Regulator 7805 is utilized to stabilise the rectified DC. Capacitor C3 at the output of the regulator bypasses the ripples present within the rectified DC output. LED1 shows the status of the USB power booster circuit.
Assemble the power booster circuit on a general purpose Printed Circuit Board (PCB) and enclose in a appropriate cabinet. Bring out the +5V, ground and data points within the type-A socket. Connect the data cables as assigned within the circuit and the USB power booster is all set to function.
This circuit is available in PDF file, you may download the file from the following link:
» USB Power Booster Circuit