Questions tagged [ttl]
Transistor Transistor Logic. Logic circuits built from bipolar transistors and resistors.
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Communicating with 6 TTL devices that support the Modbus protocol
I am working on project using Hukseflux SR05-D2A2 thermal sensors. These sensors support Modbus communication through a TTL interface. The objective is to read the value at a specific address in the ...
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How do I know if it's RS232 levels or TTL levels
I have a random device: GT MEDIA V8 Finder Pro. I would like to communicate over its console port.
Here are some pictures of its mainboard. Here is the area around the console connector:
I have no ...
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How to calculate the resistor values for the zener diode and the BJT base?
I try to convert ~12V signal from a car button (the input voltage can be from 10V to 14V) to a logic level signal for MCU, but the signal should to be inverted (1 = 0, 0 = 1).
Below is my schema, but ...
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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 ...
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Why do 74-series counters label their enable pins T and P?
A few 74-series counter ICs I’ve looked at have two enable pins, and they’re labeled “T” and “P” (for example, the 74LS161A, or 74ALS867A). The “T” input affects the ripple carry out, and the data ...
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Power supply for medium-scale 74HC TTL circuit
I've developed an 8-bit computer, in the same vein as Ben Eater's wonderful 8-bit computer series. It's based on a collection of 74HCxx-series ICs, and fits (in theory!) on a single PCB board. I'm ...
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Bare esp32 chip auto programming mode help
So I'm very much a newbie when it comes to using bare chips but since I'm trying to make a project which requires very small modules for wifi I'm stuck using a bare one. My question would be how to ...
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Simplest circuit to provide a 0 or 1 TTL signal to a device
Please excuse the naivity of this question, I am not an electrical engineer. I need a quick solution, and don't have time to ask our electrical engineer to help. A supplier will bring a device they ...
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Schottky TTL current calculator [closed]
I have a problem from university where I have to calculate the I ccl. I am a little bit confused because I don't know how to do it.
The problem says as well that Schottky TTL state is 0 logic (I think ...
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J-K flip-flops TTL to CMOS
The following uses 3 TTL 74SLS76N J-K flip-flops, which are active low:
However, I'm trying to figure out what the settings for the PR and CLR inputs would be using CMOS CD4027 J-K flip-flops. For ...
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Understanding cascasing of 74185
The 74185 is a binary-to-BCD converter. It is designed cleverly utilizing the fact that both 10 and 2^n are divisible by 2 once, thereby omitting processing of the LSB entirely. More interestingly ...
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ESP32 custom hardware connection to USB-UART converter
I'm designing custom hardware based on the ESP32. I'm using Adafruit's ESP32 Huzzah as a reference. In the Adafruit design, an onboard CP2104 USB-to-UART chip is used, but I will be programming the ...
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Which MAX3232 IC's for simple UART to RS232 converter?
I am trying make a TTL to RS232 converter.
I have designed my PCB for 16 pin SMD sop16 and max3232 CSE+. But when I was buying from a store (store link), I saw other types of max3232. I've bought and ...
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Raw mode control of USB device via TTL
An industrial device can be connected to a host computer via a standard USB port.
The USB port on the device itself is indeed a CH340 USB-to-TTL converter, which allows to control the device through a ...
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BJT circuit with totem pole output
In the circuit above, I don't understand how to close and open the BJT that I circled.
To be specific, I think that when I give input 1 the circled BJT should be opened, but how? What is the voltage ...
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What does "limit of 1 TTL LS load" mean?
If I read that a line has a limit of 1 TTL LS load, does it mean that I can attach only a TTL gate? I know that other options exist, for example, the HC, however, in the case I have only LS gates, how ...
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Do stateful 74LS series chips start in a defined state?
Specifically, 74161 counters and 74377 registers, can I rely on them to be full of zeros on power on?
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What is this chip called? [closed]
I need a TTL chip 74 series, that takes in some amount of inputs and one enable bit. When the enable bit is high, the output is the same as the input. When the enable bit is low, the output is all low....
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K155ID1 power dissipation
I build my own nixie clock with four digits (IN-14, 10k anode-resistor) with a seperate K155ID1-IC for each digit (so no multiplexing). Also, I am only using the 0-9 range, so every tube has one digit ...
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ESP32-C3-WROOM: error flashing chip
I am developing an ESP32-C3-WROOM custom board, but when I tried to flash the chip using UART (FT232D USB-TTL) and Arduino IDE, I got the message "A fatal error occurred: Failed to connect to ...
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Could I have a whole batch of bad AT26C16 EEPROM chips?
I am in TTL chip heaven (India) where I can get these things for pennies on the dollar, so I bought batches of chips to tinker with. Among them a 16 AT28C16 EEPROMs, looking like new, and then 2 very ...
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To drive current with open-collector gate when input is high, do I need a buffer or an inverter?
Once upon a time I knew the answer, or could just try it. But with distance I forgot. When I use an open collector, I do it to drive some load. So High means current is flowing. But when it is used as ...
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Frequency counter schematic
I was wondering what's wrong with my Proteus schematic.
This schematic is supposed to show the frequency in Hertz on the display but instead only three zeroes are displayed.
Is there any component ...
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74xxx logic. Cheapest, most space saving way to invert 10 logic outputs
Please see this circuit.
I'm trying to design a circuit that allows you to use a single button to increment a counter from 0 to 9 (then it will loop). Diode logic will convert the 10 logic outputs to ...
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Is there a standard way of doing a TTL Hi-Z buffer?
I found many examples of IC internals for CMOS Hi-Z (tristate) buffers, but none for the TTL family.
I guess that in the TTL world, the "open collector" is much more common, but I see that ...
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Schematic Review: PIN diode switch driver
I've designed a PIN diode RF switch driver, specifically to drive HP33000 series switches. Unfortunately, these are very old, and not much documentation exists, so I'd like to ask for advice from ...
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Correcting the lower output level of a square wave generator
I have assembled a square wave generator following this schematic from an old book.
R1 and R2 are both 1 kohm, C1 is 68 pF, and C2 is 2.2 nF. The author of the book claims that this combination is ...
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Extending signal duration
I have DMM which is producing pulse with duration of around few microseconds. The pulse need to be sampled in PLC, which has sampling rate of 1ms. In other words the cycle loop can't be reduced to ...
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1 wire to 2 wire bidirectional UART
I'm working on diagnostics program for my old GM diesel, the old GM diagnostics uses a 1 wire bi directional serial protocol, 5v HIGH, 0v LOW, with the PCM data line being held high when idle, and the ...
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Connecting Arduino to Keithley external trigger
I need to connect digital output pin of Arduino Uno to Keithley DAQ6510 digital multimeter external trigger input. Both are utilizing 5V TTL logic.
Now when I measure the voltage on external trigger ...
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Confusion In Fanout of Logic Circuit and Transistor
Fanout:-Maximum Gate we connect to output of any Logic gate.
so there is limited number of gate we connect the output of Logic Gate.hence there is some minimum condition required for operation of ...
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How worried should I be about a short circuit lasting a couple nanoseconds? [duplicate]
Say I have two driver gates hooked up to each other in the following arrangement:
In theory when A goes low, for a brief amount of time B will be shorted while the 7404 inverter gate switches. Around ...
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FT232RL Chip is not working (USB to TTL)
I used an FT232RL chip to make a USB to TTL converter using the schematic below.
Although I can send a message and the TX LED is lightining up, I cannot receive any messages.
Can anyone see a problem ...
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How to correctly terminate a TTL line between two ICs?
I am designing a circuit to convert a 5ns ECL signal to an LVTTL signal of >10ns. The SY100ELT25 is used to convert the ECL to 5V TTL which is then fed into the SN74LVC1G123 to further reduce the ...
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Peak/envelope detector circuit for 30 MHz sine pulses with a 10 kHz PRF
My goal is to input 30MHz sine pulses, with a pulse width of 10us and gap of 90us between the pulses. The circuit should convert this pulse train to a TTL signal that goes from 0 to 5 volts.
To ...
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MAX3232: Switch between RS-232 and TTL levels
Sorry in advance, electronics noob here!
I need to make a proof of concept to get some data out of third party system which handles both RS232 and TTL levels.
The computer/raspberry/arduino shall - I ...
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Advantages of using 2 NPN transistor NOT gate
Is there any benefit using 2 NPN transistors for a NOT gate rather than one NPN transistor?
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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 ...
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Can I repair CY62256 with UT62256
The CY62256-55PC(SRAM) in my old computer is broken and I need a replacement for it but I can't find the same chip. The only one similar enough in my local store is UT62256CPC-70LL, HM62256ALP-12 and ...
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Reduce 3.3 V-8.4 V signal to 3.3 V input
I have a digital input signal which can use anywhere between 3.3 V and 8.4 V to signal "1", and I need to make this safe for a 3.3 V input on a microcontroller (RP2040).
I currently have a ...
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What is the shortest pulse a controller can count?
I want to count short LVTTL pulses (about 20-25 nanosecond.)
Right now, I use an Arduino with four IN74AC161N binary counters, but this solution has some Arduino limitations.
I count pulses, send the ...
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Tying open-collector outputs to TTL inputs
I know that open collector outputs are effectively either 0 V or high-Z.
I also know that TTL chips tend to read a disconnected output as high, but that really you should have something like a 1 kΩ ...
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Why does the TTL NAND gate use a 4 transistor design instead of 2?
Why does the TTL NAND gate use 4 BJTs to make the gate when it could be done using only 2?
I assume that the design with the 4 transistors amplifies the current so multiple levels of gates can be ...
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Fan-Out Calculation on LTSpice
I need to find the fan-out of the circuit below. This is a Schmitt Trigger TTL NAND Gate. How can I exactly find the fan-out of the given circuit using LTSpice or calculate it theoretically?
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I'm designing a 4-bit GPU and I need some suggestion about the RAM for it [closed]
I'm working a 4-bit GPU, the GPU run on 1.023MHz (1023kHz) clock while CPU only run on 127kHz so I need a screen buffer for it when the CPU is working on some instruction. The display I use is a 24 x ...
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TTL voltage drop
I recently bought a lot of TTL components like 8-bit registers, bus transceivers, etc. to build an ALU and 2 registers. My issue is that when I build a register, the voltage drops to 4.2, sometimes ...
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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 ...
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Can MAX485 TTL-to-RS-485 module be used as UART-to-RS485 module?
I'm trying to make a bridge from Modbus til Home Assistant using an ESP8266 (as outlined here), which uses an UART-to-RS485 module.
I have this MAX485 TTL to RS-485 Interface Module.
I'm not competent ...
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I have a JK flip-flop circuit that works in simulation, but not with real components on a solderless breadboard
I'm building a control mechanism for a seat heater in my car. Eventually, it will drive power relays to control the current to the heating elements. It works in a simulation on simulator.io, but it ...
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How do you make a three input NOR Gate function as two input NOR Gate?
Hi this is my first question!
So I'm clearly a beginner in electronics and studied for months, now the topic I've studying is logic gates and boolean algebra also the TTL ic. I've been curious if how ...
