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Monday, January 23, 2012

Amazing Cylon Flasher/ halloween night Light




The scanning eye of the Cylons is awfully similar to the one that KITT had on Knight Rider. It's possible that KITT was built by Glen A. Larson using recycled Cylon technology. As some people have pointed out, the scanner also similar to the eye of the robot Gort in The Day the Earth Stood Still
Although the basic premise is the same, for some reason there are a lot more KITT circuits than Cylon circuits floating around on the net. (There are some Cylon circuits; Here is one that looks complicated!) The starting point for our circuit is the "standard" KITT scanner circuit. There are quite a few variations on the basic theme, and we'll pick and choose the parts that we like.
This circuit is based around the CD4017 decimal counter chip. This is a chip that counts the cycles of a clock signal that is input to one of its pins. It counts from 0 to 9, sequentially turning on the outputs labeled #0 through #9 as it counts, and then it starts over. We will use outputs #0 through #5 to light up our six LEDs in order, and then use the output values #6 through #9 to light up the LEDs in the opposite order, like so:
                              
LED Number
Turned on by count value
4017 output pins
1:
#0
3
2:
#1 or #9
2 or 11
3:
#2 or #8
4 or 9
4:
#3 or #7
7 or 6
5:
#4 or #6
10 or 5
6:
#5
1


There are a number of ways to provide the clock signal. One nice way is to use a standard 555 timer chip. Both the 4017 and the 555 are CMOS chips capable of operating with a 9 V power supply, so we'll set things up (1) to use a convenient single 9 V battery and (2) to use a 555 timer chip. 555's are almost as cool as Cylons. While I used the power-hungry NE555, you can also use the power-efficient version, the ICM7555.

We'll build the circuit in a few separate blocks to keep things neat and orderly. All of the parts that we're using are quite common; any decent electronics shop (i.e., not Radio Shack) should have everything that you need. (If you do have trouble locating parts, take a look at the list of "Suggested Parts" down below.)

Step 1: Let's start by wiring up the 555:
Solder the 9 V battery connector where the battery is shown, with the negative (black) wire to pin 1 and the positive (red) wire to pin 8. We'll refer to these points later as "Ground" and "+9 V", respectively. (Yes, picky people, it's an effective ground, not an earth ground.)
Pin 8 is connected to pin 7 through a 180 kilo-ohm resistor, and pin 7 is connected to pin 6 through a second a 180 kilo-ohm resistor. The 0.22 uF capacitor connects pin 6 to pin 1.
Use a wire to connect pin 2 to pin 6. Pins 4 and 5 should be left unwired.
Pin 3 is our "clock" output, which we'll be taking to the 4017 in the next part of the circuit.
Note added: It's an excellent (but optional) idea to test the output of the 555 at this point, to make sure that the clock signal is really coming out. You can do that as follows: take the output from the 555 and connect it, through a 330 ohm resistor, to an LED and then to ground. If everything is correct so far, the LED should blink rapidly.

Step 2: Wire up the inputs to the 4017
.
There are quite a few connections to the 4017 chip, so we'll split them into two diagrams for ease of reading.
First, connect the clock output from the 555 to the clock input at pin 14.
Besides the clock input, there are four other inputs to the 4017. Wire pin 16 to the + 9 V, either at pin 8 of the 555 or directly to the red wire from the battery connector. The remaining three connections are to the ground, so wire pins 8, 13, and 15 to the black wire from the battery connector or to pin 1 of the 555.

Step 3: Building some easy "OR" gates
Connect a diode, such as a 1N914 or a 1N4001, to each of the ten decimal output pins of the 4017 and wire the cathodes of those diodes as shown, forming six outputs that will drive the LEDs. Pin 12 is left unused.
[If you want to know why we're using the ten diodes, please see the aside at the end of the story.]

Step 4: Driving the LEDs
You can hook your six LEDs directly to the outputs shown above; just connect the LED between where it says "For LED X" and ground, with the cathode side towards ground.
Well, that's the easy way. It works, and it looks good. But if you look closely, it's a little too perfect. The lights in the original Cylons were incandescent, not LEDs, and the effect is quite different. LEDs turn on and turn off very quickly. The result is that the lights in our circuit seem to blink on and off, rather than smoothly transition from one light to the next. In order to slow down the transitions, we can also use a low-pass driver circuit to drive each LED. To do this you will need six 47 k resistors, six 47 microfarad capacitors, six 2N3904 transistors, and one 330 ohm resistor.A low-pass LED driver consists of a low pass filter and a simple NPN transistor amplifier. To build one, begin by connecting one the outputs from the previous step ("For LED X") to a 47 kilo-ohm resistor. The other end of the resistor connects to the base of a the transistor.
The base of the transistor also connects to a 47 microfarad capacitor. The other end of the capacitor is connected to the Emitter of the transistor (labeled with an "E" in the diagram) and to ground (the negative terminal of the battery). The capacitor is probably a polarized type, meaning that it must be hooked up with the side labeled "-" (or a big stripe) towards ground. To hook up the LEDs, start by attaching a single 330 ohm resistor to the + 9V supply. The LED connects from the 330 ohm resistor to the unused pin of the transistor, the Collector. (You can hook all six of the LED anodes to the same 330 ohm resistor, so you will only need one of those.)

Circuit Diagram Of Cylon Flasher






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