Friday, December 27, 2013

Dicing With LEDs

Every self-respecting DIYer makes his own electronic dice with LEDs as spots. Then you don’t have to throw the dice anymore – just push the button. The electronics also ensures that nobody can try to improve his luck by fiddling with the dice. Too bad for sore losers! This circuit proves that an electronic die built using standard components can be made quite compact. The key component of here is a type 4060 digital counter (IC1). This IC has an integrated oscillator stage, so only two resistors (R7 and R8) and a capacitor (C7) are necessary to generate the clock signal. The clock signal is divided by various factors by the internal digital circuitry of the IC.

The division factors are designated by ‘CT’ in the IC drawing symbol. For instance, the signal on the CT3 output (pin 7) is a square wave with a frequency equal to the clock frequency divided by 23 (8). The clock signal is divided by 24 (16) on the CT4 output, by 25 (32) on the CT5 output, and so on. This means the output signals form a binary number that Dicing with LEDs counts upwards, which is naturally what a counter does.Of course, a die has only six possible values marked on the six sides of a cube. This means that at least three bits (the first three outputs) of the counter are necessary to drive a display. Eight different counter states (23) can be represented with three bits, but in this case the counter must be restricted to six states.

Dicing With LEDs Circuit Diagram

dicing-with-led-circuit diagram
dicing-with-led-schematic-circuit diagram

To make sure this happens, D11, D12 and R6 are used to reset the counter to its initial state when it reaches the seventh state, which means when it reaches a binary count of 110. When this happens, pins 4 and 5 of the IC are both logic ‘1’ (high level), which causes a logic ‘1’ to be applied to pin 12 via resistor R6. This causes the counter to be reset, which is what we want. The display consists of seven LEDs arranged in the same pattern as the usual markings on a normal die. 

This arrangement is shown in the schematic diagram. Before you begin thinking about the proper logical connections between the LEDs and the counter outputs, you can start by noting that except for the ‘1’ state there will always be two LEDs lit up at the same time. This means that only four distinct indications are necessary, instead of seven (with a total of seven LEDs).Another advantage of this is that the current consumption can be reduced by connecting pairs of LEDs in series. Resistors R1–R4 limit the current through the LEDs to approximately 2 mA. This means you have to use low-current LEDs. They are nice and bright at a current of 2 mA. Resistor R3 has a higher value because only one LED is driven via it.

For convenience, the circuit is dimensioned based on using a 9-V battery. The current consumption of the circuit depends on the number of LEDs that are illuminated, and with our prototype it varied over a range of approximately 2.5 mA to 6.5 mA. The LEDs still produce enough light even when the supply voltage is as low as 6 V, but this depends strongly on the characteristics of the low-current LEDs used in the circuit. Diodes D8–D10 and transistor T1 are necessary to enable all the states of a normal die to be shown. By that, we primarily mean the states with two or three spots, which must be located diagonally. For readers who want to delve more deeply into the design, the following table shows the six different binary states, which LEDs are lit up for each state, and the number of spots shown by the die.

The die is operated by switch S1. In the quiescent state, the break contact of S1 is closed and the oscillator is stopped because the input of the oscillator stage is connected to ground via the switch. When S1 is pressed, the oscillator starts running and causes the states of the LEDs to change at a rate of 1 kHz, which is too fast to follow with the naked eye. This high frequency ensures that the state of the die is purely random when S1 is released, so there is no regularity or pattern in the results. The circuit can be assembled on a small piece of perforated prototyping board. Fit the LEDs in exactly the same pattern as shown in the schematic diagram, since otherwise the spot patterns will not correspond to a real die. When you have assembled the circuit board, fit it in a plastic enclosure along with a 9-V battery to provide power.


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Wednesday, December 25, 2013

Re using fused tube light by 4 diode

A tube-light get fused due to use from a long time. You may notice that a used fluorescent tube-light get black colored on the both end of it. This circuit is to light-up those fused tube-light.
Have you think about re using a fused tube light? (Which is usually thrown out). Well here I’m showing a simple circuit using 4 diode for re-using a fused tube light.

use fused tube-light




The circuit diagram shown above is quite simplified from basic tube light wiring diagram by adding a bridge rectifier. Bridge rectifier provides high voltage DC to the both end of tube. All we have focused in this project is to lighting-up the weak tube using high voltage DC.

Note: A fully damaged or broken tube-light could not be light-up anyway. Use those tube-light for this project that is still trying to light-up but not fully lightened on the basic connection of tube-light.
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Monday, December 23, 2013

Speaker Headphone Switch For Computers

If you need to use a headset with your PC, then you will know how frustrating it is continuously swapping over speaker and microphone cables. This is even worse if the PC is parked in a dark corner and the hard-to-read writing on the sound card sockets is covered in dust. This simple switch box eliminates all these problems. It sits on top of the desk and connects to the PC with stereo one-to-one cables.

On the rear of the box are sockets for the PC speaker and microphone connections and the existing speakers. On the front of the box are the sockets for the headset microphone and headphones, an input for an external microphone and two switches. One switch is used to direct the sound card output from the PC to either the existing speakers or the headphones.

Circuit diagram:

Speaker-headphone switch for PCs circuit schematic

Speaker-Headphone Switch Circuit Diagram For Computers

The second switch connects either the headset microphone or the external microphone to the input socket of the PC sound card. The switches used were 3 position 4 pole rotary switches with the last pole unused and adjusted for 2-position operation. All sockets were stereo 3.5mm types. This multiple switching arrangement is very flexible and is especially handy if you want to use an external microphone while monitoring with headphones.

The ground wire as well as the left and right wires are all switched to prevent noise that could otherwise be induced into the microphone input through joining separate earths. For the same reason, a plastic case is used so that the earths of the sockets are not shorted together as would happen with a metal case. You will require two additional short stereo extension cables to connect the box to the PC.
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Saturday, December 21, 2013

Simple 0A° To 360A° phase shifter Circuit Diagram

Each stage provides ° to 180° phase shift. By ganging the two stages, 0° to 360° phase shift is achieved. The 2N3070 JFETs do not load the phase shift networks.



 Simple 0A° To 360A° phase shifter Circuit Diagram

Simple 0A° To 360A° phase shifter Circuit Diagram


 Simple 0A° To 360A° phase shifter Circuit Diagram 
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Thursday, December 19, 2013

Simple Power Consumption Limiter Circuit Diagram

A Simple Power Consumption Limiter Circuit Diagram solenoid driver uses incandescent lamp filaments as on-indicators to limit power consumption. High magnetic reluctance (opposition to flux) in the coil of an armature-driven device, such as a solenoid or relay, calls for a surge of activation current, followed hy a lower de level to remain on, since surge to on-current ratio is typically 5:1. The cold filament allows a surge of coil-activation current to pass through; as the filament heats up, it throttles the current to a more reasonable hold value. The solenoid driver circuit offers these features: 5-V logic swings turn the power-MOSFET switch, Q1, fully on and off. 1vo low-cost flashlight lamps, in parallel, handle the peak current. Because their de current is only 50% of peak and because they operate at 60% of their rated voltage, the lamps have an operating life of 12,000 hours. Further, the lamp filaments` positive temperature coefficients raise each filament`s resistance. This rise in resistance eliminates current-hogging problems and provides short -circuit protection. The steady-state on-current is 700 mA, vs. 1700 mA without the lamps. A 4.6-V min supply rating allows battery operation. 

 Power Consumption Limiter Circuit Diagram


Simple Power Consumption Limiter Circuit Diagram
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Tuesday, December 17, 2013

Intelligent Battery Charging Circuit Diagram

Intelligent Battery Charging Circuit Diagram. Intended for a Nicad application this charging circuit can be used with a wide range of batteries. A low-battery detector is intended. The trip voltage is set via the 500-kQ pot. Select Rc for the battery you intend to use.

Intelligent Battery Charging Circuit Diagram

Intelligent Battery Charging Circuit Diagram

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