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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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 senses 00 hours. 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 The and triggers on the rising-edge. I came to a point where I thought I had gotten the design, so I proceed to build the clock. When the capacitor stops charging up, the 22K pull-down resistor pulls the clock input down to a logic 0.

74LS393 Dual 4-Bit Binary Counter

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. This falling edge triggers the 74LS to advance one more time.

I realized a design flaw when I finished the clock. After overcoming the noise problem with the 74LSs in the clock, I learned of another minor design issue. The fundamentals of my binary clock circuitry was based on Hans Summer’s binary clock, but his operates in hour mode.

I had to use a very small 8-volt transformer that just barely fits inside the case to supply the low voltage power. The other segments for the zero are all wired together and switched on and off by a flip-flop. The two diode AND gate, one connected to segment F and one to the inverted segment G, will produce a logic 1 only when segment F is on and segment G is off.


Even a seconds display can be added dataasheet this circuit, simply add two more decoder chips on U3b and U4a. Recall that the 74LSs trigger on a falling edge, not a rising edge.

None of the other digits have this trait.

Motorola 74LS Series Datasheets. SN74LS, SN54LS, 74LS Datasheet.

The “C” that is switched on to make a zero comes on when the clock is in the single digit hours. I think if the 74LS operated on a rising edge, the circuit dxtasheet work without the capacitor and resistor. Click here for the schematic diagram of the four B nixie clock.

I tossed this idea out and decided to drive the nixies directly, using BCD-to-7segment decoder chips. 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. 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. 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.

There, you have it, a “double” pulse to get rid of the 00 hours. However, that didn’t work out due to complications with the circuitury and the amount of room in the clock case I made. 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.


Without the K resistor and 0. The pulse goes high then low, and the falling edge triggers the 74LS These versatile nixie tubes datwsheet allow for a variety of characters and digits with different styles. A colon indicator can be added by using the 1Hz pulse off pin 5 of U3a. Most chips come with four AND gates in one, or 6 datsaheet in one. I found a “trait” of the 7-segment zero digit, segment F has to be on and segment G has to be off.

This would’ve been a bad waste of chips, so I decided to do the remaining logics the old school way I originally planned on using a Mostek MK 6-digit clock chip that multiplexes the digits.

I experimented with using 74LS dual binary ratasheet chips. I built a case out of cedar, and the amount of space I had inside the case was rather limited so I was unable to pursue my idea of using neon bulbs or Fatasheet for displaying the binary time directly from the 74LS counters.

74ls393 datasheet pdf

The inverter using a transistor and resistor changes the “off” G into a logic 1 for the AND gate. However, after trying the chip 74s393 with two nixies, I found that the brightness was not very strong. The 74LS clock input triggers on a falling-edge of a square wave when the square wave signal drops from a logic 1 to 0.