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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To a circuit, this means switch is on, and switch is off and this happens at a faster than expected rate for a short time. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

You need to de-bounce your switches in order to get predictable results. 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 74ls4n capacitor to the other leg of the same button.

If using a switch to Vcc you need a pull down resistor say, 10K ohms to ground.

I connected pin3 clock to ground through a 10k resistor in addition to having the push button from power. I get the feeling that I connected something wrong initially. Digital circuits catasheet fast and see the bounces.

Sad news is when you use a push button, “bouncing” happens. The traditional solution for switch inputs is to put the switch between the input pin and ground. 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.


The reason is that the input current is much less when high than when low, so less power is wasted on the unused function. When the button is pressed, the capacitor is shorted until the button is let go, then the capacitor charges up. As it happens, datashfet can do this cheaply by using the unused half of the chip as a SR flip-flop. I did the following: I’ll amend my question to make it more clear. Like this 7l4s74n example:.

74LS74N Datasheet PDF – Motorola => Freescale

This basically means the connections in the button datawheet and close very fast more than you would like. Sign up or log in Sign up using Google. For bipolar TTL, such as the 74LS74 and the OP mentions, you would need a very low value pull-down resistor as the inputs source current.

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. Including the inverse-clear and inverse-set for the half of the you are using. 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.

Try increasing the resistors to ohms or 74lss74n. You can’t have floating inputs. I successfully made an SR FF. Note the pull up resistors at the inputs of both NAND gates. Because of this, the clock is seeing multiple pulses when you intended on making only one.


If you use too low of a voltage source, then the circuit will not operate. Since the inputs source current, they must be datasheeg Low with a small under 1K resistance to be seen as a logic Low.

And do you have a 0. Is there a point where I may consider the chip is not functioning properly?

Like this for example: Inputs can not float. 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.

74LS74N Datasheet

Adtasheet as a guest Name. A 74LS74 has a nominal rating of 16 mA when low. Logic ICs should never have floating inputs. Also, connect a resistor from the clock input pin 3 to ground. Better practice is to connect the switch between input and ground, to give a solid Low when the switch is closed.

If using a switch to ground you need a pull up resistor again, say, 10K ohms to Vcc. Given this bouncing trouble, the SR FF feeding the clock sounds very clever so I will try this one again to establish if bouncing 74s74n indeed the root cause of my frustrations.

Home Questions Tags Users Unanswered. Make sure by power you mean the positive side of a 5 volt DC source.