74LS08 IC is a member of 74XXYY IC series. There are four AND gates in the chip and each gate have two inputs, hence the name. 74LS SN74LS08NSR. ACTIVE. SO. NS. Green (RoHS. & no Sb/Br). CU NIPDAU. LevelC-UNLIM. 0 to 74LS SN74S08D. ACTIVE. Note The ”Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaran- teed The device should not be operated at.

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The chip is basically used where AND logic operation is needed.

Because output is nothing but voltage across resistor R1 it will be LOW. Looking at the image I agree. At this time the total VCC appears across resistor R1. You could try adding a pull down resistor k, K, ohm, doesn’t much matter your inputs may be floating high.


In that case, the left button should have a red wire on the lower left pin.

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The 5K1 pull-up resistor ensures that the pin is seen as High when the switch is not pressed. It is really popular and amd available everywhere. If you choose the wrong pair, you end up with an always on switch. Sign up or log in Sign up using Google.

74LS08 – Quad 2-In AND Gate

I 774ls08 tried switching to a 9v battery and nothing changes. If you do use a pull down resistor, make it low like PeterBennett recommended. Sign up using Facebook.

Simon Marcoux 1, 2 They 74la08 notorious for that particular mishap. For better understanding the internal working let us consider the simplified internal circuit of AND gate as shown below. Sign up using Email and Password. When both buttons are not pressed. In the circuit two transistors are connected in series to form a AND gate. TL — Programmable Reference Voltage. By using our site, you acknowledge that you have read and understand our Cookie PolicyWnd Policyand our Terms of Service.


74LS08 Pinout, Configuration, Equivalents, Circuit & Datasheet

Email Required, but never shown. The circuit working can be explained in few stages below: After verifying the three states, you can tell that we have satisfied the above truth table.

This LED is connected to detect the state of output. Pull down resistors as suggested in another answer nad, might also a good idea. Pressing the buttons does nothing.

It might be oscillating as well. With that the drop across resistor R1 will be zero. The inputs with both switches unpressed allow the pins to float around, depending on the way the IC is set-up internally.

Output of the AND gate is the voltage across resistor R1. A few mentioned below. I think that you were dead on in the first place with your answer SaraHeart. With the LS you need to sink 1.

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