74LS74N Datasheet, 74LS74N PDF, 74LS74N Data sheet, 74LS74N manual, 74LS74N pdf, 74LS74N, datenblatt, Electronics 74LS74N, alldatasheet, free. The SN54 / 74LS74A dual edge-triggered flip-flop utilizes Schottky TTL cir- cuitry to produce high speed D-type flip-flops. Each flip-flop has individual clear and. This device contains two independent positive-edge-trig- gered D flip-flops with complementary outputs. The infor- mation on the D input is accepted by the.

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Is there a point where I may consider the chip is not functioning properly? If using a switch to Vcc you need a pull down resistor say, 10K ohms to ground. Post as a guest Name. Sign up or log in Sign up using Google.

There are quite a number of changes you need to make. Inputs can not float. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Note the pull up resistors at the 74la74n of both NAND gates. You can’t have floating inputs. Home Adtasheet Tags Users Unanswered. I get the feeling that I connected something wrong initially.

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CMOS parts 74ACxx, 74HCxx, and others with a “C” are CMOS and have very high impedance inputs – they can be used with high value pull-up or pull-down resistors – but ALL inputs must be connected somewhere, else they may be seen as “maybe” levels, and cause the chip to draw excessive current.

Digital circuits are fast and see the bounces.


Until its sufficiently charged, the logic level will be one for a period defined by the resistor and capacitor values. Logic ICs should never have floating inputs. When 74ls74j button is pressed, the capacitor is shorted until the button is let go, then the capacitor charges up. The inputs of bipolar TTL logic 74xx, 74LSxx, and others without a “C” datashet the middle of the part number source current, and will normally appear as a High when not connected.

The resistor is used to provide a default logic level to the clock, which in this case is logic level zero since the resistor is connected to ground. A 74LS74 has a nominal rating of 16 mA when low. For bipolar TTL, such as the 74LS74 and the OP mentions, datsaheet would need a very low value pull-down resistor as the inputs source current. Since the inputs source current, they must be pulled Low with a small under 1K resistance to be seen as a logic Low.

Like this for example:.

74LS74N Datasheet

And do you have a 0. If you use too low of a voltage source, then the circuit will not operate. Adding a 5K or so pull-up resistor is good practice, but usually not necessary. Better practice is to connect the switch between input and ground, to give a solid Low when the switch is closed.

Sad news is when you use a push button, “bouncing” happens. If using a 74os74n to ground you need a pull up resistor again, say, 10K ohms dagasheet Vcc.

As it happens, you can do this cheaply by using the unused half of the chip as a SR flip-flop. I tried unsuccessfully to make an SR flip flop out of it too. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.


Datasehet need to de-bounce your switches in order to get predictable results. Sign up using Facebook. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. I’ll amend my question to make it more clear.

The easiest fix but not the prettiest is to connect a capacitor across the button one leg of the capacitor to one button leg, and the other leg of the same capacitor to the other leg of dwtasheet same button. The reason is that the input current is much less when high than when low, so less power is wasted on the unused function. It’s not bad for ddatasheet purposes, but if later on you decide to never use the set or clear operations of the chip, you could tie them directly to power.

As WhatRoughBeast pointed out, you need to apply this practice to all inputs. This basically means the connections in the button open and close very fast more than dxtasheet would like.

74ls74n Pin Diagram – Wiring Diagram Explained

I tried the arrangement you outlined. Like this for example: Given this bouncing trouble, the SR FF feeding the clock sounds very clever so I will try this one again to establish if bouncing is indeed the root cause of my frustrations. I datasneet made an SR FF.