Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [ttl]

Transistor Transistor Logic. Logic circuits built from bipolar transistors and resistors.

This tag should be used when talking about digital circuits built purely from bipolar transistors and resistors. Transistor Transistor Logic is the logic that makes up the backbone of most electrical devices today. It's what you would find at the core of an arduino, a computer, or a smmartphone.

539 questions
26
votes
8 answers

Is it worth it learning how to use 7400 series "jelly bean" logic IC's or are they completely obsolete?

My road map for learning electronics included the 7400 series logic chips. I started in on electronics by following the labs in the "Art of Electronics" lab manual which includes labs with these chips. I ended up building several custom Microchip…
Dave.Mech.Eng
  • 1,745
  • 3
  • 17
  • 21
25
votes
8 answers

What are the advantages of using FPGAs over TTL in intro computer architecture?

I teach the one and only computer architecture course at a liberal arts college. The course is required for the computer science major and minor. We do not have computer engineering, electrical engineering, other hardware courses, etc. My primary…
Ellen Spertus
  • 1,609
  • 4
  • 20
  • 23
22
votes
3 answers

What does a two overlapping circles symbol mean in an electrical schematic/diagram?

In the datasheet for a A3503 Hall Effect Sensor, I saw a circuit diagram labeled 'Functional Block Diagram', and it shows a symbol I have not seen before. It's shown here between 3 - Output and 2 - Ground. What is this supposed to represent? The…
Ehryk
  • 1,141
  • 5
  • 16
  • 28
17
votes
2 answers

How does TTL serial work?

I've been trying to find a good description of the TTL serial "standard" without much luck. I understand that serial transmit (TX) and receive (RX) lines idle high (at VCC) and that they drop to ground when a bit is transmitted. As such, they're…
blalor
  • 2,544
  • 3
  • 22
  • 24
17
votes
11 answers

Why was so much TTL logic design "negative true"?

I've been spending time with schematics debugging busted 1970s TTL-based computing circuits. I'm sure this is a more general question but I'll ask it in this context since that's what I'm exposed to. Why is so much TTL circuitry designed around…
BZo
  • 1,575
  • 1
  • 11
  • 22
14
votes
4 answers

What logic family is best for general-purpose hobbyist stuff?

I need to buy a few logic ICs. Which family should I get? HC? HCT? Which kind is best to have lying around in a parts box, for maximum compatibility with unpredictable future projects? Wide supply range, no extreme frequency requirements, etc. …
endolith
  • 28,494
  • 23
  • 117
  • 181
13
votes
1 answer

How is this circuit for level converting (5V<>3.3V) working?

Does anybody know, how is this circuit exactly working? It is level converter between 5V and 3.3V logic and it is bi-directional. I have some theory, but I am not sure with it (I never worked with MOSFET before). And what is that diode for? I take…
vasco
  • 957
  • 2
  • 15
  • 25
11
votes
2 answers

Does this circuit have marginal voltage level problem?

As a research for the problem I described here I found this circuit by Maxim: This is clock doubler, and must be a really good fit in my case as input frequency is very well defined. However looking through the datasheets I found that MAX9010…
Anonymous
  • 6,908
  • 1
  • 14
  • 41
10
votes
2 answers

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 elements. However, MC is kinda overkill and…
Sergio
  • 340
  • 1
  • 10
10
votes
4 answers

Buffering a Digital Microcontroller Signal for Connecting to an Optocoupler

I frequently work on projects in which I use optocouplers for isolating digital +5VDC control signals (for example, from a microcontroller) from the rest of the circuit. However, since these work by illuminating an LED inside the device, there can…
teeeeee
  • 765
  • 4
  • 18
10
votes
6 answers

Rising edge pulse detector from logic gates

The circuits I describe are entirely made of 7400 series logic gates (7402, 7404 and 7408 ic). I'm trying to build a rising (positive) edge pulse detector using logic gates. The following circuit should work in theory: (see this) I do not expect…
nc404
  • 309
  • 1
  • 2
  • 11
10
votes
4 answers

Should I use CMOS vs. TTL?

Now, I know that this question has been asked so many times that it seems like I'm trolling, but I must point out that I couldn't find the right answer to this question anywhere. So yeah, CMOS and TTL are different. Logic levels, speed, drive…
fuzzyhair2
  • 1,927
  • 15
  • 23
9
votes
3 answers

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 start: HCT -> 5V TTL HC -> CMOS technology AHCT…
Kralik_011
  • 307
  • 2
  • 9
9
votes
6 answers

Multiplexing UART

I'd like to interface my main microcontroller's hardware serial port to more than one device at the same time. My understanding is that UART on my microcontrollers is based on an active-low 5V TTL. (I know what I'm explaining here can be technically…
David Refoua
  • 285
  • 1
  • 4
  • 18
9
votes
1 answer

How to convert a digital signal from 24V to 5V

I have an industrial automaton that gives me a digital signal (24V or 0V) on its outputs and I want this signal to control an integrated circuit, but the integrated circuit only takes a TTL signal in its input (0 to 5V). I think it can be controlled…
Pierre B
  • 193
  • 1
  • 1
  • 5
1
2 3
…
35 36