Thursday, 14 October 2010

AC powered LED

Posted by doctor on 12:55 0 comments

The circuit below illustrats powering a LED (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must pass current in both directions, a small diode is connected in parallel with the LED to provide a path for the negative half cycle and also to limit the reverse voltage across the LED. A second LED with the polarity ...
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Additional Power Supply For USB

Posted by doctor on 12:38 0 comments

we get the problem on a PC or laptop in reading the USB device. problem that often arises is unable to read the usb device. This is caused by a lack of supply voltage. to solve this problem let's try to make additional power supply.     Scheme  :   list the components needed :     Electrolit Condensator 47Uf/25V    Electrolit Condensator 47Uf/16V    IC AN 7805 with heatsink...
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