3 Description. The SNx4HC08 devices contain four independent. 2-input AND gates. They perform the Boolean function Y = A ○ B or Y = A + B in positive logic. 74HC08 Datasheet, 74HC08 Quad 2-input AND Gate Datasheet, buy 74HC 74HC08D from NEXPERIA >> Specification: AND Gate, 74HC08, 2 Input, mA, 2 V to 6 V, SOIC
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Where should I connect the LED on pin 2 of ? You need to repeat it six times to check all gates. If your parts are reallyand with no letters other than possibly L or LS in the middle, like 74LS04 they are bipolar TTL logic, and require a 5 volt power supply for correct operation.
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If the parts have a C in the middle 74C04 or 74HC04they are CMOS, and the inputs are very high impedance, and will be in an 744hc08 state when not connected – they must be connected to the positive supply for a High, and to ground for a Low.
Now remove the wire and connect pin1 to GND this time.
Negative to the GND via a resistor. I have the above IC and I want to check them before using them. The 74HC parts can use a power supply between 2 volts and 6 volts.
But keep the switch and LED connections as they are. What can I do to test them? It is important to give the correct part numbers!
You are halfway through. Positive of LED to pin 2. Whiskeyjack 3, 2 16 Get the pinout correct. You do need a current-lilmiting resistor Ohms or so in series with the LED, but with pin 1 tied to Vcc, the output of the inverter on pin 2 will be Low, so the LED won’t light.
Sign up using Email and Password. Here is the pinout diagram:. Connect an LED to pin 1 and pin 2 each along with current limiting resistors. If this gives you too much trouble mentally, use unused inverters to switch the input and output polarities.
Here is the pinout diagram: Now take a wire and connect pin1 to VCC. The inputs of bipolar TTL parts will usually appear as logic High 1 when not connected.
And TTL outputs are much better at sinking current rather than sourcing it, so don’t try to drive an LED output to ground. Then shouldn’t the diagram I drew above work?
You must connect the inputs directly to ground to have them seen as a Low 0.
Here are circuits to use with, for instance, the and