74LS, 74LS Datasheet, 74LS Dual 4-bit Binary Counter Datasheet, buy 74LS, 74LS pdf, ic 74LS 74LS SN74LSNSR. ACTIVE. SO. NS. Green (RoHS. & no Sb/ Br). CU NIPDAU. LevelC-UNLIM. 0 to 74LS SNJ54LSFK. Each of these 74LS monolithic circuits contains eight masterslave flip-flops and additional gating to implement two individual four-bit.

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However, I had to delay the pulse from the DRL until the 10 minutes counter finished sending its clock pulse to the 1 hours counter. The 74LS clock input triggers on a falling-edge of a square wave when the square wave signal drops datashet a logic 1 to 0. When the capacitor stops charging up, the 22K pull-down resistor pulls the clock input down to a logic 0.

74LS Dual 4-Bit Binary Counter :: Micro JPM

Even a seconds display dahasheet be added to this circuit, simply add two more decoder chips on U3b and Vatasheet. I was faced with the problem of the clock starting at 00 hours, but the clock does count nicely to 12 and resets back to One advantage to use what is essentially a binary clock with 7-segment decoders is to have small neon bulbs or LEDs driven directly from the BCD outputs. I designed the clock circuitury hoping to achieve a perfect design that uses all of the logic available in all of the chips I would need.

The pulse goes high then low, and the falling edge triggers the 74LS Most chips come with four AND gates in one, or 6 inverters in one.


The datasheet says the chip was designed to have a strong tolerance for noise, and 74ls339 is no mention of this in the 74LS datasheet.

These versatile nixie tubes can allow for a variety of characters and digits with different styles. As you can see in the schematic, the portion marked in blue uses two AND gates and one inverter gate. Without the K resistor and 0. For this clock, I decided to go with the traditional 7-segment display to show the time. As a result, when the clock is turned on, the 1 is always on.

This configuration helped solve the problem.

74LS Fairchild Semiconductor, 74LS Datasheet

However, that didn’t work out due to complications with the circuitury and the amount of room in the clock case I made. I figured that with the in the front, it would buffer out more of the noise and generate a cleaner clock pulse for the 74LS chips.

When the clock goes to 10, 11, or 12, the “C” is turned off so the digit 1 appears. I tossed this idea out and decided to drive the nixies directly, using BCD-to-7segment decoder chips.


I personally prefer hour mode. I never had a problem with this in my other two clocks that run off mains, and I discovered the reason after taking a closer look at the datasheets. The fundamentals of my eatasheet clock circuitry was based on Hans Summer’s binary clock, but his operates in hour mode. After discovering this noise problem, I swapped them around.

(PDF) 74LS393 Datasheet download

So, when the hours runs to 13, the AND gate will reset the hours to zero, then the DRL will produce a logic 1 because it datasheer 00 hours. This would’ve been a bad waste of chips, so I 74lss393 to do the remaining logics the old school way I planned on placing the neon bulbs under each digit, so if you’re plain then look at the Bs and if you’re a geek then look at the binary below.


A colon indicator can be datasheer by using the 1Hz pulse off pin 5 of U3a. It took some experimentation before I could get the signals to work correctly between the chips. The reason is because if segment F is off or segment G is on inverter produces a logic 0then the diode s will pull down the output to ground and produce a logic 0.

The “C” that is switched on to make a zero comes on when the clock is in the single digit hours. I built a case out of cedar, and the amount of space I had inside the case was datashset limited so I was unable to pursue my idea of using neon bulbs or LEDs for displaying the binary time directly from the 74LS counters. The and triggers dataheet the rising-edge. Assembly and Testing Completed view of assembly bottom view Back to Top.

I figure since the latter was normally used in older computer systems, the power supply and input signals are expected to be well-filtered and free of noise.