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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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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. Also, connect a resistor from the clock input pin 3 to ground.

I successfully made an SR FF. I get the feeling that I datasheft something wrong initially. Make sure by power you mean the positive side of a 5 volt DC source. It’s not bad for experimentation 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.

74LS74N Datasheet

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Is there a way to test it with a simpler configuration?

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. Since the inputs source current, they must be pulled Low with a small under 1K resistance to be seen as a logic Low.

When the button is pressed, the capacitor is shorted until the button is let go, then the capacitor charges up. I tried unsuccessfully to make an SR flip flop out of it too. Because of this, the clock is seeing multiple pulses when you intended on making only one. WhatRoughBeast 49k 2 28 Including the inverse-clear and inverse-set for the half of the you are using. Home Questions Tags Users Unanswered. Better practice is to connect the switch between input and ground, to give a solid Low when the switch is closed.


The traditional solution for switch inputs is to put the switch between the input pin and ground. You need to de-bounce your switches in order to get predictable results. 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.

And do you have a 0. 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.

I’ll amend my question to make it more clear. Digital circuits are fast and see the bounces. You can’t have floating inputs. 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. Note the pull up resistors at the inputs of both NAND gates.

The input of digital circuits needs to be either on or off. If you use too low of a voltage source, then the circuit will not operate.

Email Required, but never shown. Is there a point where I may consider the chip is not functioning properly? The inputs of bipolar TTL logic 74xx, 74LSxx, and others without a “C” in the middle of the part number source current, and will normally appear as a High when not connected.


Adding a 5K or so pull-up resistor is good practice, but usually not necessary. Post as a guest Name. If using a switch to ground you need a pull up resistor again, say, 10K ohms to Vcc.

Try increasing the resistors to ohms or so. I did the following: If using a switch to Vcc you need a pull down resistor say, 10K ohms to ground. Sign up using Email and Password. Inputs can not float. 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 74os74n leg of the same button.

By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that 74ks74n continued use of the website is subject to these policies. As it happens, you can do this cheaply by using the unused half 74la74n the chip as a SR flip-flop.

74ls74n Pin Diagram – Wiring Diagram Explained

Sign up or log in Sign up using Google. Feeling confident, I used a blinking circuit to feed the clock pin3 with the same set up I had initially and got the led from Q1 to blink, then I did the same for the second half of thebut the clock2 pin11 being fed by Q’1 pin6.

I connected pin3 clock to ground through a 10k resistor in addition to having the push button from power. Sad news is when datashert use a push button, “bouncing” happens. Until its sufficiently charged, the logic level will be one for a period defined by the resistor and capacitor values.