All Questions
Tagged with ttl integrated-circuit
26
questions
0
votes
1
answer
283
views
Failsafe circuit for a bistable latching solenoid
I am new to embedded circuits and working on a problem with which I need help.
I am using ESP32 soc for controlling a bistable valve using DRV8833 driver module. Please refer to this link for valve ...
- 101
2
votes
1
answer
137
views
74HC74D initial output value after power up
I use a touch sensor (Active Low) to light up a light bulb. here I've used a 74HC74D D flip flop to turn on an off the bulb with the sensor pulse (sensor output is active low which is then converted ...
- 335
0
votes
1
answer
73
views
How can I find reverse current of 74lsXX integrated circuit
I'm using 74lsXX ICs for my 4-bit computer. I noticed that 74XX ICs have reverse current at the input; I know that the output of the IC allow the reverse input current flow back to it.
But I'm a bit ...
- 165
1
vote
1
answer
323
views
Why does the 74LS32N behave like an AND gate?
First of all I am a beginner.
I am practicing with the 74LS32N (OR Gate) IC , I noticed that it behaves like an AND gate instead of an OR Gate.
Only when both the inputs are 1 , the output is 1 , (Led ...
- 11
0
votes
1
answer
187
views
74HC08N doesn't latch [closed]
I am using the 74HC08N chip. Why doesn't the first AND gate latch itself?
I have connected the output of the first AND gate to its own input.
I have used two resistors, the one on top is a pull-up and ...
- 11
2
votes
1
answer
405
views
74LS47/74LS247 BI/RBO-pin usage
I am currently playing around with a 74LS247 BCD to 7 segment decoder. The basic usage for decoding works perfectly fine.
But I would like to test out everything this IC has to offer including the ...
- 21
0
votes
1
answer
718
views
CMOS vs TTL power and impedance
I need to compare and contrast a CMOS IC with a TTL IC. I've chosen a quad 2 input NAND gate IC, 7400 for the ttl version and 4011 for the CMOS. I'm having a bit of trouble with 2 of the requirements.
...
- 21
1
vote
3
answers
3k
views
The circuit with 74HC138 is working, but with 74LS138 it is not, why?
I used 74HC138 in the first circuit and 74LS138 in the second circuit.
Only the one with the 74HC138 is working.
Why?
- 31
0
votes
1
answer
88
views
Are there combo gates XOR followed by AND? (4-bit identity comparator)
Is there no 4 bit identity comparator in TTL or CMOS? It could fit into a DIP-12 package as all it would have is 4 XOR gates for selectable invesion and 1 4-way AND gate.
OUT := (A1 xor B1) and (A2 ...
- 1,541
9
votes
3
answers
7k
views
Using HC/HCT, AHC/AHCT series logic
I am builing a circuit, and i need to connect a few different IC's (obiosly). My circuit is based on 5V TTL logic and i found a part that is made only in AHC/AHCT variant.
So let's take it from the ...
- 307
0
votes
1
answer
610
views
1 TTL IC -> inverter + 2-input NAND + 3-input NAND
I came across this question in my homework:
Implement the following gates using only one TTL IC: one inverter, one 2-input NAND and one 3-input NAND.
The type of IC they're talking about has 14 pins,...
- 59
0
votes
3
answers
1k
views
TTL IC logic high output doesn't reach high enough voltage
I've been having a problem trying to build a breadboard circuit.
The problem being, that some IC high outputs doesn't reach a high enough voltage, staying around ~2V. That is not sufficient for a ...
0
votes
5
answers
1k
views
RS485 IC Termination Resistor Configuration
I've made a mistake on a design, that went into production...
It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the ...
- 528
10
votes
2
answers
2k
views
How to manufacture chip on board?
I am a developer of a cheap product and i have no experience in mass production. Device is fully functional and represents a single sided PCB, a microcontroller, a bunch of diodes and a few passive ...
- 340
1
vote
3
answers
253
views
Multiple Demultiplexers In Series
Basically I need some demultiplexers to switch between 24 outputs. The data inputs would be connected to counters for the addresses. I'm currently using 74ls138 3-8 line demultiplexers. Is this ...
- 11
0
votes
2
answers
72
views
Bredboard compatible FAST TTL [duplicate]
I have been looking for 16-bit ICs for a project i`m working on. The project is to build a 16-bit computer from scratch, therefor i decided i nedded cgips that could handle high clock-frequensies. ...
- 49
2
votes
1
answer
2k
views
Combining CMOS and TTL logic
I have a bunch of 74LS383 (TTL octal transparent latch with three-state outputs) and MM74C83N (CMOS 4-bit binary full adder) that I would like to connect together. I need to connect the output of the ...
user17592
1
vote
4
answers
3k
views
How to implement 8-bit 2:1 multiplexers on a PCB?
I need to implement a 2:1 multiplexer for 8-bit data. That is: as inputs it should take two 8-bit numbers and a Select line; and as output an 8-bit number.
I could use two 74HC(T)157s (this is a quad ...
user17592
3
votes
1
answer
251
views
Is there relation between logic chip names and their internal structure
I know that for instance an ATMega328 is a 8 bit MCU with 32k of program space, the same can be said for most other MCUs and some other ICs with a direct relation between the name and internal specs. ...
- 492
2
votes
2
answers
6k
views
Possible to use 7447 to drive common-cathode 7 segment display?
I know that the 74(LS)47 is designed to drive common-anode displays. However, is it possible to make it drive a common-cathode display? What is the simplest (in terms of components) way of doing this?
- 445
1
vote
2
answers
6k
views
Difference between 7446,47 etc
I have looked in the data sheets, as well as the TI article, but I am still unsure of the answer to this question:
What is the practical difference between a 7446 ("BCD to 7 segment decoder/driver ...
- 445
1
vote
1
answer
475
views
How could I efficiently implement this "TTL load"?
I'm attempting to test a parameter of an IC to the specifications listed in the data sheet. The data sheet describes the following load circuitry for the output:
The data sheet notes that CL be 50pF ...
- 476
5
votes
3
answers
2k
views
Driving LEDs / other small loads with a 74HC06 or similar inverter
I was recently reverse-engineering some firmware (and other bits) from a router, and spotted that the front panel LEDs were driven from a 74HC06 hex inverter gate chip rather than a proper LED driver.
...
- 10.8k
4
votes
2
answers
12k
views
What is the fastest 7400 series family? Is 74VHC faster than 74AHC?
What is the fastest 7400 series logic family?
Is 74VHC* faster than 74AHC*?
This list does not seem to be in any particular order:
http://en.wikipedia.org/wiki/7400_series
- 1,163
4
votes
3
answers
2k
views
IC chips and datasheets
I'm still just beginning my adventure into electronics and IC chips and datasheets have me confused so I'm going to ask a series of beginner questions will help me and hopefully others as well.
There ...
- 1,708
0
votes
2
answers
274
views
Three-state inverting octal buffer
I'm looking for a three-state inverting octal buffer for a replacement part for an old microprocessor lab. The package should be DIP. Ucc should be on pin 20. Chip select should be at pins 1 and 19 ...
- 3