R1_____________220R 1/2W Resistor
R2,R5,R6,R8____100R 1/4W Resistors
R10,R12,R14____100R 1/4W Resistors
R3_____________220R 1/4W Resistor
R4,R7__________330R 1/2W Resistors
R9_____________560R 1/2W Resistor
R11____________820R 1/2W Resistor
R13______________1K2 1/2W Resistor

D1___________1N4004 400V 1A Diode
D2,D4,D6__BZX79C2V7 2.7V 500mW Zener Diodes
D3,D5,D7,D8,D9,D10 Red LEDs (Any dimension and shape) (See Notes)

This device, connected to the loudspeaker output of an audio amplifier, will indicate the instantaneous output power delivered to the loudspeaker(s) by means of six LEDs illuminating one after another by voltage values increasing little by little, providing the visual impression of a luminous bar or column, increasing and decreasing in height following the increase and decrease of the signal’s level.
The input signal is first rectified by D1 and then sent to six different voltage dividers, one for each LED. In this way, the indication provided by the LEDs illumination of this “Power Display”, will be related to the instantaneous power sunk by the whole loudspeaker cabinet.
Six output power levels are displayed by the LEDs in a 2W - 80W range (no setup required). Each nominal power level indication into 8 Ohms load is reached when the respective LED illuminates at full brightness.


* The output power indicated by each LED must be doubled when 4 Ohms loads are driven.
* The circuit can be adapted to suit less powerful amplifiers by reducing the number of LEDs and related voltage dividers.

Voltage range: 0.7 - 24V
Current limiting range: 50mA - 2A

Gambar Rangkaian

P1____________500R Linear Potentiometer
P2_____________10K Log. Potentiometer

R1,R2___________2K2 1/2W Resistors
R3____________330R 1/4W Resistor
R4____________150R 1/4W Resistor
R5______________1R 5W Resistor

C1___________3300µF 35V Electrolytic Capacitor (see Notes)
C2______________1µF 63V Polyester Capacitor

D1,D2________1N5402 200V 3A Diodes
D3_____________5mm. Red LED

Q1____________BC182 50V 100mA NPN Transistor
Q2____________BD139 80V 1.5A NPN Transistor
Q3____________BC212 50V 100mA PNP Transistor
Q4 __________2N3055 60V 15A NPN Transistor

T1_____________220V Primary, 36V Center-tapped Secondary
50VA Mains transformer (see Notes)

PL1____________Male Mains plug

SW1____________SPST Mains switch

Device purpose:

A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist’s workbench. This circuit is not an absolute novelty, but it is simple, reliable, “rugged” and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. Well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.

* P1 sets the maximum output current you want to be delivered by the power supply at a given output voltage.
* P2 sets the output voltage and must be a logarithmic taper type, in order to obtain a more linear scale voltage indication.
* You can choose the Transformer on the grounds of maximum voltage and current output needed. Best choices are: 36, 40 or 48V center-tapped and 50, 75, 80 or 100VA.
* Capacitor C1 can be 2200 to 6800µF, 35 to 50V.
* Q4 must be mounted on a good heatsink in order to withstand sustained output short-circuit. In some cases the rear panel of the metal box in which you will enclose the circuit can do the job.
* The 2N3055 transistor (Q4) can be replaced with the slightly less powerful TIP3055 type.
* Excellent quality-price ratio: enjoy!
Earlier slated coarsely for 2010, AMD fine-tuned the expected release time-frame of its 12-core "Magny-Cours" Opteron processors to be within Q1 2010. The company seems to be ready with the processors, and has demonstrated a 4 socket, 48 core machine based on these processors. Magny Cours holds symbolism in being one of the last processor designs by AMD before it moves over to "Bulldozer", the next processor design by AMD built from ground-up. Its release will provide competition to Intel's multi-core processors available at that point.

AMD's Pat Conway at the IEEE Hot Chips 21 conference presented the Magny-Cours design that include several key design changes that boost parallelism and efficiency in a high-density computing environment. Key features include: Move to socket G34 (from socket-F), 12-cores, use of a multi-chip module (MCM) package to house two 6-core dies (nodes), quad-channel DDR3 memory interface, and HyperTransport 3 6.4 GT/s with redesigned multi-node topologies. Let's put some of these under the watch-glass.

Socket and Package
Loading 12 cores onto a single package and maintaining sufficient system and memory bandwidth would have been a challenge. With the Istanbul six-core monolothic die already measuring 346 mm² with a transistor-load of 904 million, making something monolithic twice the size is inconceivable, at least on the existing 45 nm SOI process. The company finally broke its contemptuous stance on multi-chip modules which it ridiculed back in the days of the Pentium D, and designed one of its own. Since each die is a little more than a CPU (in having a dual-channel memory controller, AMD chooses to call it a "node", a cluster of six processing cores that connects to its neighbour on the same package using one of its four 16-bit HyperTransport links. The rest are available to connect to neighbouring sockets and the system in 2P and 4P multi-socket topologies.

The socket itself gets a revamp from the existing 1,207-pin Socket-F, to the 1,974-pin Socket G34. The high pin-count ensures connections to HyperTransport links, four DDR3 memory connections, and other low-level IO.

Multi-Socket Topologies
A Magny-Cours Opteron processor can work in 2P and 4P systems for up to 48 physical processing cores. The multi-socket technologies AMD devised ensures high inter-core and inter-node bandwidth without depending on the system chipset IO for the task. In the 2P topology, one node from each socket uses one of its HyperTransport 16-bit links to connect to the system, the other to the neighbouring node on the package, and the remaining links to connect to the nodes of the neighbouring socket. It is indicated that AMD will make use of 6.4 GT/s links (probably generation 3.1). In 4P systems, it uses 8-bit links instead, to connect to three other sockets, but ensures each node is connected to the other directly, on indirectly over the MCM. With a total of 16 DDR3 DCTs in a 4P system, a staggering 170.4 GB/s of cumulative memory bandwidth is achieved.

Finally, AMD projects a up to 100% scaling with Magny-Cours compared to Istanbul. Its "future-silicon" projected for 2011 is projected to almost double that.

I needed to calculate the voltage on a capacitor after a given time, and also needed to calculate the time required to charge a capacitor to a given voltage.. maths being rusty (and losing my SC which had all the formulas programmed in ) I resorted to Excel.

The attached .xls (in .zip) may be of use to others.. it contains 2 simple routines..

1.) Given applied voltage, R, C, and time (t), it outputs the instantaneous voltage across the capacitor at t.

2.) Given applied voltage, R, C, and the voltage required across the capacitor, it outputs the time at which this voltage appears across the capacitor.

You will need the LN() function installed in Excel or (other spreadsheet) If you have an RC circuit, you can solve the following differential equation:

EMF = Vr + Vc (Kirchoff's Voltage Rule)
Vr = IR = (dq/dt)*R
Vc = Q/C
EMF = (dq/dt)*R + (Q/C)

After solving the 1st order differential equation, you get
q = C(EMF)(1-e^(-t/(RC)))
i = dq/dt = (EMF/R)e^(-t/(RC))
This is for a DC circuit where the capacitor and resistor are in series.
Download the file from for a console C++ program to help you design a voltage divider from the resistors you have on hand. The included document also has a simple resistor storage method my wife came up with that lets me find any resistor value I want in a few seconds. There is also an Open Office spreadsheet file that calculates resistance for round and rectangular wire; I find it handy for designing shunts.

Edit 26 Jul 2009: redesigned the program and added the spreadsheet. The resistor.cpp program now does both voltage divider calculations and can find two resistors that can be used to make up a desired resistance value.

Here the scheme of amplifier behringer


: Part Total Qty. Description Substitutions C1 1 See Notes R1 1 See Notes D1 1 1N914 Diode U1 1 4011 CMOS NAND Gate IC K1 1 6V Relay S1 1 Normally Open Push Button Switch MISC 1 Board, Wire,
My Zimbio
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