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Questions tagged [ttl]

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

38 questions with no upvoted or accepted answers
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3
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0answers
99 views

Switch between USB and Bluetooth module TTL

In my project I have an MCU that I want to communicate with via 5V TTL serial. I have two methods of doing this in my circuit, USB via an FT232R (5V) and Bluetooth via an HC-05 module and level ...
2
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0answers
296 views

L298 distorts signal

I connected STM32 F334R8 microcontroller to L298 H-bridge. I made some measurements. The problem is output signal on L298 has quite slow slopes and is not as sharp as input signal. I do not understand ...
2
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0answers
598 views

RS232 to TTL converter problem

I have a RS232 to TTL Converter which has 4 pins Vcc, Tx, Rx, GND . I am trying to make a serial communication with my PC. I have a AVR development board and I have tested my program by connecting ...
1
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1answer
49 views

What's the phase relation between the sine wave and the sync output from a function generator?

I'm using a function generator to generate a sine wave, and am trying to use the sync (TTL) output to flash an LED at the beginning of each wave pulse. However, when I compare the sin wave and the ...
1
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0answers
320 views

RS-232 Level Shifter

Most PCs don't have RS232 built-in anymore. So the only option is USB-2-RS232 adapters or RS232 PCI-E card. While I expected the adapters to output a low voltage it turns out most RS232 PCI-E card ...
1
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0answers
210 views

CP2108 with level converter txb0108 - UART communication TTL and LVTTL

My project uses four different modems (one 3v3 LVTTL(?) and three 5v TTL) for AT communication. Each modem has a UART interface (TTL compatible). For my application, i chose the CP2108 to ...
1
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0answers
196 views

Composite video out from 74AHCxx gates with 16MHz clock. Insane?

just for fun and while waiting for other components to arrive I want to build a composite video out from available hardware. So please no suggestions to just by a propeller. Available hardware: ...
0
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0answers
49 views

TTL “radio-button” using priority encoder and latch

I'm liking this site and I am not always using it to just throw a question but to develop ideas all the way. First time I did that was on StackOverflow I need JSZip and gzip for my web page, and JSZip ...
0
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0answers
30 views

Reverse Feedback protection in a RC circuit

I have been working on a model CPU build from LS TTL ICs for the past couple of weeks. I am going to give a little background here, during the prototyping I stumbled upon several intresting issues ...
0
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0answers
52 views

TTL 10µs wide generation on CMOS rising edge?

I want to use a DG645 from Stanford research to trigg two different laser. To do this, I need four 10µs negative TTL signal. The DG645 send +5V CMOS signal (picture below). Since I have a little ...
0
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0answers
55 views

Voltages at nodes in TTL logic gate

I'm trying to answer the question that has been given here. I think I understand which transistors are on and which are not under the two different logic states i and ii. However, what I really ...
0
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0answers
39 views

Signal conversion LVDS, RS422 and LVTTL

What are all the parameters required to LVDS to lvttl, RS422 to LVTTL and LVTTL to LVDS and RS422 signal conversion?
0
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0answers
88 views

Deciding between ULN2804 or ULN2803 with 74HC595

I'm making a circuit with Arduino + 74HC595 + (ULN2804 / ULN2803) to drive a few 12 V Motors. I'm trying to decide whether to use the ULN2804 or ULN2804. On testing, performance of both is fine, ...
0
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0answers
49 views

Setting measurement points of the 74HC86 delay time

simulate this circuit – Schematic created using CircuitLab I'm measuring a propagation delay and transition delay of a 74HC86 chip. I setted somewhat high frequency square-wave signal(100kHz) ...
0
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1answer
42 views

Unpowered 74ls chips vs Powered Nano?

I have a power-hungry 74ls digital logic project that I want to connect a USB-connected Arduino Nano to, but I'm not sure how design the interface between them safely. The project has an external 5V ...
0
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0answers
83 views

Why can't I get the output of a 74LS221 to idle at 5 VDC?

I have an industrial machine with an encoder feeding a Measurement Computing USB-CTR08 counter board. In order for the board to count the pulses the counter's gate ...
0
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0answers
56 views

Serial communication between raspberry and laptop not giving right values

I want to communicate between a Raspberry Pi 3 model B and a laptop using a USB to RS-232 cable and this RS-232 to 3.3V TTL converter via the serial module in Python: GND is connected to board pin #6 ...
0
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0answers
36 views

UART Current in PIC18F46K22 & 7404 Input Current

I am currently making a decision to invert the UART signal from my PIC18F46K22 and have 2 choices to either use 74LS04 and 74HC04 but there is a difference between the LS and HC that the LS can output ...
0
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1answer
72 views

TTL gate characteristics

In case of BJT for example, the input characteristics can be described with \$I_B=f(V_{BE})\$ and output characteristics with \$I_C=f(V_{CE})\$. How can the input and output characteristics be ...
0
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2answers
130 views

74AS TTL to CMOS pull up resistor and maximum speed (or lowest delay)

Hello I have to pilot a CMOS input 5V chip device with a 7474 flip flop with the lowest possible delay to minimize clock jitter. Signal is about 11.3 Mhz I have two options: 1) 74HC74 (CMOS ...
0
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0answers
154 views

Are pull-up resistors mandatory for inputs on modern parallel ports?

Here I go again testing more circuits on two computers with each reporting completely different data yet I feed the same data in. Now this time, the data coming back is all logic highs on my laptop ...
0
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1answer
207 views

Difference between MAX3430 and ADM483 for TTL-RS485 Converter

I want to use TTL-RS485 Circuit as in the attachment. The circuit is working when I use ADM483 Transceiver for U1. It can provide communication. However the circuit is not working when I use MAX3430 ...
0
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2answers
157 views

HC-SR04 Distance Sensor Trigger Signal on 2.5V Voltage level gives no reading

I am using an Arduino on a breadboard setup with an ATMEGA328p MCU. The whole circuit is designed to work in a low-power state and is powered using a 3V (Nominal) voltage Coin Cell. The HC-SR04 is ...
0
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1answer
76 views

Driving a ThorLabs piezo controller with TTL external input

I am trying to drive a ThorLabs piezo controller (https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=2421&pn=KPZ101) with an external +3.3V TTL signal provided by a microcontroller (using ...
0
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0answers
46 views

Clear D flip flop internal logical scheme

I am new in this community and also in logic circuit design and digital electronics. I couldn't find the logical design on the internet for the following D flip flop and i would like to know how it's ...
0
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0answers
33 views

Are differential line drivers “active” circuits?

Some quadrature encoder datasheets describe their outputs as either Differential Line Driver or Line Driver. On closer inspection of the diagrams, they appear to be the same thing (differential line ...
0
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0answers
111 views

Why does a 74LS189 RAM chip light-up an LED connected to its re-inverted output when data word is HIGH while a 7489 RAM chip cannot?

I have thought on it a lot and summarizing my confusion here. I have two SN7489N chips whose Ioh is 20uA (not sufficient to light-up an LED). Correct me if I'm wrong that Ioh is the maximum current it ...
0
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0answers
36 views

Does anyone knows the SmartGen LINK Port protocol?

I need to replace an SG72A controller in a machine, I would like to make a cable or small component to It, because I have no time to wait for this to came from China to Brazil. I didn't found any ...
0
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1answer
50 views

A question about max TTL input of a converter device

I have a programmable f/I converter which can be modified for various types of inputs and outputs. They have also a more detailed manual. I read them and learned how to configure and set this device. ...
0
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1answer
26 views

How can I output to one of 4 different outputs without using a demultiplexer?

I do not have a demultiplexer available, so I need a substitute. I have a TTL signal and I need to output the signal to output 1, then output 2, then output 3, then output 4 in sequence, meaning that ...
0
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1answer
40 views

Changing from 8 channel to 16 channel. Does change in voltage input affect upgrade?

I am going from a Numato 8 channel GPIO to a Numato 16 channel GPIO. The 8 channel I/O pins support 5V TTL signals but the 16 channel I/O pins support 3.3V TTL signals. If the input to the I/O of the ...
0
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1answer
383 views

TTL gate function

Can you explain the logic function of this TTL gate? I think it is $$ Y = \overline{AB+CD} \ $$ but I am not sure. If $$ V_1=5V \\ V_2=0V $$ does the transistor Q1 work in reverse-active mode?
0
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0answers
782 views

4 bit binary full adders, bcd and seven segment displays

I'm having fun with some 74LS283[1] 4 bit binary adders but I am having trouble working out how I should convert the output to a decimal which could be used to drive two 7 segement displays which are ...
0
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2answers
494 views

VHDL: Receiving Data from Terminal to FPGA using TTL

(I posted same question in stackoverflow but didn't get right answer) I'm newbie in VHDL. So today, after UART Tx, I tried to read Datas that coming from Realterm terminal. I only wrote Rx codes to ...
0
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1answer
498 views

TTL or RTL, which is better?

Is there an advantage to using one or the other?
-1
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1answer
96 views

Using RXD to generate Audio signal and serial communication all connected to each other

I'm using RXD to transfer audio to an amplifier (1) and TTL communication with USB/TTL converter (2) for communication. Everything works but I can not get maximum output from the amplifier. When I ...
-1
votes
1answer
98 views

What would be logic value of high impedance TTL output connected to LED

Suppose a TTL output in high impedance is connected to a LED, which is also connected to a resistor, which is then connected to ground. No circuit interferes between TTL output and LED, between LED ...
-4
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1answer
170 views

TTL NAND logic circuit

how can find the maximum fan-out of the TTL-NAND gate using LTSpice ? i tried to solve problem by hand, but the problem how to find fan-out using ltspice