Questions tagged [logic-gates]

Symbolic representation of ideal devices implementing boolean functions

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Chip based logic, NOR by sn74hc02n analog [closed]

I think I'm not understand something obvious when trying to implement the complex logic(half-adder) by NORs. Possible to simplify my question, why in this position the diod is emitting: In this state ...
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Minimalist 3-input XOR gate using CMOS

As an enthusiastic noob to CMOS and after browsing multiple examples of XOR gates using PMOS and NMOS but finding it hard to find any good examples of 3-input XOR gates, I found an example of a 4 FET ...
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Lower transistor count CMOS implementations of XOR and/or XNOR with leakage current only for all static input combinations

I'm perfectly fine with the 10- and 12-transistor implementation(s), see e.g. en.wikipedia on XOR gate CMOS implementation. There are variations of 6-transistor pass-gate XOR implementations (...
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3 transistor XOR gate

I am very new to electrical engineering. But I am working on a hyper reduced fully functional RISC architecture. This is mostly finished, I have a compiler for it and the emulator is not fully ...
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How can I implement my binary countdown from the output of JK flipflops to two seven segment displays from 15-0?

I am currently making a 2-way traffic stoplight. The stoplight signals are now fully functional. I have no idea how I can implement the 4 bits (not including my MSB because I just need to display 15-...
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Where do Data in /Out, Write Enable, and Read Enable Wires connect to in RAM?

This is a screenshot of the Crash Course Video Registers and RAM #6. From YouTube, here's the link "Crash Course Video". It's talking about using Gated latches to store memory, and putting ...
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OR gate with momentary output

I have 8 different boards that can be triggered via capacitive touch and I need to feed into one input of a microcontroller. Whenever one board goes HIGH, the microcontroller's input should also ...
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NOT gate using triodes

I can't understand the functioning of the circuit of a NOT gate using a triode (vacuum tube) and a resistance (big rectangle connected between the triode's anode and the positive power supply). For ...
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Need to drive several 5 V LEDs from 3.3 V logic

I have done similar level shifting several times using discrete components. This time, due to a need of driving some number of 5 V LEDs from a 3.3 V microcontroller, I prefer to use some level shifter ...
Sener's user avatar
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Can you detect when an incrementing counter has reached N by AND'ing the expected set bits?

With a incrementing counter, starting from zero, I can tell when 128 is reached by looking for a positive edge on bit:7. I can detect when 129 is reached by looking for a positive edge on (bit:7 & ...
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Simple TTL: Is there a way to "detect" a high-z state and easily use that to drive other logic?

I have two TTL style logic chips, call them A and B (*), where the outputs of A are the inputs to B (think: 8 data lines). A has tri-state outputs, so when they are turned off they float. B is an ...
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How to write the truth table for this CMOS circuit

How would you get the truth table for this CMOS circuit where there are two outputs 'A' and 'B' and one output 'Out'? And from that, how would you derive the the Boolean expression along with the ...
Sabreen Kaur's user avatar
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Current flow in NOT gate with transistors

I was studying NOT gates, and I can't understand why current stops passing in LED when the switch is on. If the potential difference between top and bottom is 5V, should current always flow between ...
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Problem understanding reset circuit for mini PCIe cards

On my hands I have an Ekahau Sidekick 1, which is a device for measuring the Wi-Fi, and I've been analyzing its PCB for quite a moment now. It is composed of one main compute module(SMARC-FIMX6 from ...
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Logic gate AND with a bug [duplicate]

I'm doing an AND gate in a circuit using 2 transistors BC337-40. I'm also using an LED in series and a 680 Ohms resistor. I expected the LED to light up only when both transistor bases were HIGH. But ...
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AND gate IC - "SN74LVC1G08DBVR" is giving a wrong output

I am working on a boost converter circuit that gets 12Volt as input (J1) and gives 18 Volts at the output (J4). I am having issues in the feedback circuit for this converter, especially with my AND ...
Kinjal's user avatar
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Why are my logic gates are exploding in TinkerCad? [closed]

Why is this happening in my logic gates?
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Master-Slave JK Flip Flop Truth Table

In my computer logic and design class, we have gone over the different types of flip flops and their representations. I understand what the goal of the master-slave configuration is but I am having ...
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How do I make a gate with only one condition?

I need a simple gate with one condition only but with two ends, if its given 10V it will deliver a square wave from an oscillator I've built, if not then it will deliver a wave from a signal generator,...
ricsrdo.casro's user avatar
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1 answer
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9T SRAM Circuit Supporting 1-bit Multiplication

I was reading a paper that added a 3T NAND gate, consisting of two NMOS and one PMOS, to the regular 6T SRAM, achieving 1-bit multiplication. However, I'm struggling to understand how the NAND part of ...
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Is there any way to know how real discrete components are being connected to each other using logical gates?

Let's say we created some gates or something with VHDL. How can I convert that code into those diagrams that show how discrete components (such as transistors and resistors) are connected to each ...
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12 transistor XOR CMOS gate

I have come across this circuit for an XOR gate (see below) using 12 transistors in CMOS technology. I am having trouble understanding the circuit, mainly in identifying the logic gates. I know that ...
Granger Obliviate's user avatar
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Tri-state buffer, why is it called high-impedance?

I found this picture of a tri-state buffer: When the enable signal is 0, the output is disconnected from the voltage sources. But why is this called high-impedance? From what I understand impedance ...
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How do I make a gate diagram for \$a'c'+abc+ac'\$? [closed]

I have checked with the program Logic Friday and it checked the shown gate diagram, which showed me another result and came with this gate diagram: Is this the correct answer?
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555 timer and JK flip-flop activation problem

I need to toggle a MOSFET after I hold a button for 3 seconds. Here is my circuit: I have a JK flip-flop for the toggle function. When the clock pin of the JK flip-flop goes high to low, output of ...
Alican Uçar's user avatar
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Why would I use HNM (high noise margin) gate drive over a TTL gate drive for DC motor driving application?

I am making a very simple half bridge DC motor drive using the MAX1760 gate driver. Looking through the datasheet I saw that it offers two types of logic level technologies (if that's the right word?);...
tronhawk's user avatar
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Is it possible to create a logic gate design for a clocked D flip-flop register where there is a synchronous reset and an enable pin?

I'm currently designing a register where there needs to exist a data input pin (DIN), Clock (CLK), Reset (RST), and a RUN pin. The register is designed such that, only at positive edges of the clock ...
RizqiBusiness 's user avatar
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Unknown logic gate on circuit

I'm studying the CMI decoder circuit from Maniatopoulos, Antonakopoulos and Makios, 1995, but I can't understand some symbols in the diagram. They look like a small logical OR. Can anyone tell me what ...
P0nyL0v3r's user avatar
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Which is the preferred circuit layout? Horizontal vs. Vertical (Combinational logic)

I have 2 equivalent circuits Picture 1 (Compact, a bit messier) Picture 2 (Easier to read, less compact)
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Output of a logic gate when its inputs are floating

As per this answer, the output of an OR gate when one of its inputs is 1 is 1 regardless of the other inputs, even if they are floating/disconnected. However, what is the output of an OR gate when ...
Kushagr Jaiswal's user avatar
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How do I integrate this MOSFET NOR logic gate with my circuit?

I have got an H bridge circuit controlled by a bridge driver (not in the schematic here). I want to control the disabling of it cutting of the conection to ground. I need the logic of a NOR gate but I ...
Developing Electronics's user avatar
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Clock logic for 8-bit computer

I have been in the process of remaking Ben Eater's 8-bit-computer, and have a few questions. I got to the part where the clock, which consists of 3x 555 timer, is connected with logic gates. However, ...
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7404 IC Always outputting high

I'm new to electronics, and it's my first time using a hex inverter. The following pins are connected: 1(Input A)-GND or VCC 2(Output A)-LED 7-GND 14-VCC VCC is 5V, but whatever I do the output is ...
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Diodes for implementing digital logic

This diagram in this post is from Microelectronic Circuits by Sedra and Smith. The question corresponding to this picture asks to write a truth table with A and B as inputs and X and Y as outputs and ...
Hamza Beder's user avatar
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Wired AND and OR question, logic levels?

In the "wired AND and OR" gates pictured can anyone explain what the voltage levels will be for each function? For AND, I see the output is A*B and for OR, A+B. Is this correct? Also, is ...
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NAND and NOR gate, question on choice and function

I see both described in following images 1, 2 and 3. Does anyone know why image 3 has more transistors? Also, the basic advantage to using NAND or NOR gates in digital electronics? 1. 2. In the ...
notaorb's user avatar
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How to turn an LED on in an inverter circuit

I am currently trying to build an inverter circuit which turns on an LED (on a simulation before building it physically). I am using an 2N3904 NPN transistor, 5V voltage sources, a 220k and a 47k ...
iAndrea's user avatar
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Using a logic driver with a 50 ohm load

I have a load which is an external trigger input of the Highland Technology T130 single-channel picosecond EOM driver (technical manual - Google Drive link) which is 50 ohm and it requires a pulse ...
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How does this inverter make the AND-gate better?

I am very new to electronics and just started learning about logic gates. I read about the AND gate and learned about its boolean algebra, but I also wanted to make one myself using MOSFETs which I ...
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Exercise asking what a gate-level circuit output signify

This exercise from Introduction to Computing Systems from Bits and Gates to C/C++ & Beyond by Yale N. Patt and Sanjay J. Pattel asks what the value of OUT signifies in this circuit. If it's 0, ...
oabdullae's user avatar
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3 answers
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What prevents this transistor based discrete logic gate design from having been used?

I am interested in building discrete logic gates as a teaching / learning tool to explore computer fundamentals. The easiest logic gate design I can come up with consists of the following: It is ...
finitud's user avatar
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AND gate with MOSFETs to close a MOSFETs circuit

I want to add a circuit to my design in order to build a AND logic gate (preferably with MOSFETs) where in the next schematic you can find a rectangule. A and B would be the inputs, and the output ...
Developing Electronics's user avatar
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Why does the LED turn off when I touch the insulating part of the wire?

This is a NAND gate IC. I have one input connected to the positive terminal of the battery while the other input is not connected to the battery as you can see in the image. Why does the LED turn off ...
Rx6rx's user avatar
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Level shifting to lower voltage: logic-gate vs voltage divider

In my design I need to level shift 5V signals to 1.8V, for now I'm planning to use AND gates with the same 5V signal on both inputs and 1.8V as the power source. I got the idea from this document. ...
StefanoN's user avatar
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What is wrong with my Dmux8way? How can I fix it?

The problem is something with the sel spliter and the leftmost DMUX4WAY, the automatic check returned - "have different bit width and cannot be connected". But I don’t know how can I fix it. ...
Sonya Lyu's user avatar
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1 answer
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AND logic gate with diodes not working

I am currently working on an AND logic gate using 2 diodes. My first logic input is 3.3V/5mA from a Raspberry Pi Zero W GPIO pin. The second is 3.3V/500mA from a door access system. This input is ...
Omayma Raji's user avatar
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LED stays lit when using IC

I made a simple circuit with a CD4081 IC (2-input AND gates), a DIP switch, and an LED. The dip switch is set to 00 but the LED will light up regardless. The output from pin 3 on the IC appears to ...
TheTruth's user avatar
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What are the components inside ADC and DAC? [closed]

My question is this: What are the components inside ADC and DAC? Is there only transistors/logical gates and is there difference between like analog audio to digital audio ADC or other types of ADC ...
NearEternal's user avatar
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With this AND gate made of transistors, why does the LED need a resistor in parallel instead of in series?

I'm building an AND gate out of transistors. Knowing how the basics work, I built my own (naive) circuit using the following design. In testing, it didn't work like an AND gate. A B LED 0 0 Off 1 ...
Morgan Kenyon's user avatar
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Type of output of this AND Gate

I am unable to find whether the output of this IC is a push-pull output or an open drain output. I didn't notice either words in the datasheet. Hence, can someone help me to tell which output type is ...
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