Need Help on Traffic signal circuit.....

Reloadron

Joined Jan 15, 2015
5,667
Would this be homework or schoolwork? Should that be the case this should be in the homework / schoolwork sections of the forums. Your circuit is just a copy and paste of this circuit which has been around a long time. Why do you believe something is wrong with it? I assume you have built the circuit but you fail to mention what the circuit does or does not do? If wired like the link the circuit should work.

Oh yeah, your battery symbol is drawn backwards. Long line is + and short line is -.

Ron
 

Thread Starter

Sarmad Zaheer

Joined May 4, 2015
5
Would this be homework or schoolwork? Should that be the case this should be in the homework / schoolwork sections of the forums. Your circuit is just a copy and paste of this circuit which has been around a long time. Why do you believe something is wrong with it? I assume you have built the circuit but you fail to mention what the circuit does or does not do? If wired like the link the circuit should work.

Oh yeah, your battery symbol is drawn backwards. Long line is + and short line is -.

Ron
hey Ron! this is my final project for DLD(digital logic design). Our goal is to create a traffic signal without using any IC except 555 timer.
 

Reloadron

Joined Jan 15, 2015
5,667
Well, on both chips pins 4 & 8 are tied together and go to +12 Volts. Here is what I suggest you do. Take a look at the 555 Data Sheet and gain an understanding of what each 555 is doing in this circuit. Normally on a good drawing the connects are shown by using a dot, for example:

Connect No Connect.png

Your original drawing reflects the dots.

Ron
 

Thread Starter

Sarmad Zaheer

Joined May 4, 2015
5
Well, on both chips pins 4 & 8 are tied together and go to +12 Volts. Here is what I suggest you do. Take a look at the 555 Data Sheet and gain an understanding of what each 555 is doing in this circuit. Normally on a good drawing the connects are shown by using a dot, for example:

View attachment 85126

Your original drawing reflects the dots.

Ron
But that,s the problem. I didn't even know about the 555 IC before researching about it. my instructor is refusing to tell us anything about it
 

Reloadron

Joined Jan 15, 2015
5,667
The 555 Timer:

The IC was designed in 1971 by Hans Camenzind under contract to Signetics, which was later acquired by Dutch company Philips Semiconductors (now NXP).

Depending on the manufacturer, the standard 555 package includes 25 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8).[2] Variants available include the 556 (a 14-pin DIP combining two 555s on one chip), and the two 558 & 559s (both a 16-pin DIP combining four slightly modified 555s with DIS & THR connected internally, and TR is falling edge sensitive instead of level sensitive).

The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555 part number designated the military temperature range, −55 °C to +125 °C. These were available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and SE555T. It has been hypothesized that the 555 got its name from the three 5 resistors used within,[3] but Hans Camenzind has stated that the number was arbitrary.[1]

Low-power versions of the 555 are also available, such as the 7555 and CMOS TLC555.[4] The 7555 is designed to cause less supply noise than the classic 555 and the manufacturer claims that it usually does not require a "control" capacitor and in many cases does not require a decoupling capacitor on the power supply. Those parts should generally be included, however, because noise produced by the timer or variation in power supply voltage might interfere with other parts of a circuit or influence its threshold voltages.
The 555 Timer Data Sheet.

While I have no idea why your instructor refuses to tell you anything about the 555 it is among the oldest integrated circuits out there and is a very versatile IC. Maybe your instructor expects you to learn about the chip on your own studying the chip. There are volumes of text and circuits using the 555 Timer IC, more than could be covered in a single thread in this forum. For your traffic light or better put the traffic light circuit it is a matter of understanding the chip and seeing how the chip is applied. Regarding the design you posted:

This circuit also shows how to connect LEDs high and low to a 555 and also turn off the 555 by controlling the supply to pin 8. Connecting the LEDs high and low to pin 3 will not work and since pin 7 is in phase with pin 3, it can be used to advantage in this design.
Note the second 555 and how the first 555 can remove power from it.

Ron
 
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