Thursday, March 28, 2013
9 Volt 2 Ampere DC Power Supply Circuit Diagram
There is little to be said about this circuit. All the work is done by the regulator. The 7809 can deliver up to 2 amps continuous output whilst maintaining a low noise and very well regulated supply. The circuit will work without the extra components, but for reverse polarity protection a 1N5400 diode (D1) is provided at the input, extra smoothing being provided by C1. The output stage includes C2 for extra filtering, if powering a logic circuit than a 100nF (C3) capacitor is also desirable to remove any high frequency switching noise.
Circuit diagram:
C1 = 100uF-25V electrolytic capacitor, at least 25V voltage rating
C2 = 10uF-25V electrolytic capacitor, at least 6-16V voltage rating
C3 = 100nF-63V ceramic or polyester capacitor
IC = 7809 Positive Voltage Regulator IC
D1 = 1N5400 Diode
Wednesday, March 27, 2013
Simple 9 Way Cable Identifier
Here is a simple way of identifying multiple cables (with the aid of a multimeter). The circuit consists of a series of resistors, selected so that they give readings that coincide with the 1-9 numerals on the 10V scale on a multimeter switched to the Ohms x 100 range. In use, a common wire needs to be chosen and this is usually the shield wire.
The resistors go to one end of the cables to be identified, while the multimeter is used at the other end to check the values and identify each lead. Up to nine cables can be identified at a time. If a mistake is made in choosing the common lead, the readings will all be wide of the 1-9 numerals on the 10V scale, thus making the mistake obvious.
Circuit diagram:
Simple 9-Way Cable Identifier
Source : http://www.extremecircuits.net
Monday, March 25, 2013
Static 0 to 9 display
The circuit shown here is of a simple 0 to 9 display that can be employed in a lot of applications. The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1).
The seven segment display consists of 7 LEDs labelled ‘a’ through ‘g’. By forward biasing different LEDs, we can display the digits 0 through 9. Seven segment displays are of two types, common cathode and common anode. In common anode type anodes of all the seven LEDs are tied together, while in common cathode type all cathodes are tied together. The seven segment display used here is a common anode type .Resistor R1 to R7 are current limiting resistors. IC 7446 is a decoder/driver IC used to drive the seven segment display.
Working of this circuit is very simple. For every clock pulse the BCD output of the IC2 (7490) will advance by one bit. The IC1 (7446) will decode this BCD output to corresponding the seven segment form and will drive the display to indicate the corresponding digit.
Circuit diagram.
