Questions tagged [ttl]
Transistor Transistor Logic. Logic circuits built from bipolar transistors and resistors.
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Fan out of TTL Circuit
In this image When calculating the fan out of the TTL circuit
the current in the TTL drive output is 16mA and is divided into the emitters of the load each emitter has 1.6mA because the fan out is 10.
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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 ...
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Turn on/off a LED using a D-FF and a transistor
I'm trying to control a LED using some microcontroller and I designed a circuit using a D-FF and a transistor to handle it. It looks like this:
So I can control when to turn it on or of by simply ...
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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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Custom HDMI-to-( TFT or LVDS ) decoder/driver
I am working on a custom-made handheld PCB based around a PI Compute Module 3+ and one of the hardest steps I have found is how to include an HDMI-to-50pin-TTL driver on my PCB to run an LCD TFT 7&...
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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 ...
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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 ...
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Decent MOSFET for a beginner to learn from?
I am relearning MOSFETs, but more importantly I would like to focus on building some basic circuits and learning practicality over theory. I have a BSEE but haven't spent much time outside of class on ...
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Latch circuit to cycle power in an ATX PSU
I'm designing a system powered by an ATX PSU. I'd like it to be able to be switched on and off by a momentary switch but also to be able to be turned off by another input.
The latch circuit is powered ...
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How to obtain the counting of TTL pulses from an FPGA?
I'm currently working on a project in which I need to program an FPGA in order to connect it to a photon detector, that generates a TTL pulse when detecting a photon; I need to count this pulses, ...
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How to double a single TTL to link to 2 independent TTL terminal
I am working on a project that needs multiple serial connection between mcu sensors .
In order to send data by ttl serial from 1 mcu to 2 other mcu and reverse...
What is the best way to achieve this ...
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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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Connecting RS232 GPS Board to Raspberry Pi
I purchased a NEO-6M GPS board to connect to my Raspberry Pi, and when I bought it I didn't realize that it was meant for RS-232 communication instead of UART TTL (which I believe is what the ...
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TTL in an RF switch
I am hoping to find help on how to properly connect supply voltage to my switch assembly in order to actuate. My switch has input requirement of +15, -15, GND, and +5V. Also, the 5v logic inputs. ...
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LTspice - how to simulate real TTL gates?
I am trying to make simpler more general questions that might have more generally useful answers.
If you build a mixed analog digital circuit then you need to have models of real TTL or CMOS gates ...
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Issues using a 74LS245 with Attiny85
I have a Raspberry Pi, a 74LS245, and an ATTiny85.
I connected the Pi to the Tiny through 1k resistors, and am able to use SPI to program it, no problem.
I have added a 74LS245 inbetween, to ...
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XOR Gate implemented with BC547 transistors not working
I have checked and rechecked the wiring on my breadboard against the circuit shown in the schematic a dozen times and can't for the life of me understand why it is not working. Can anyone see a fault ...
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HC-SR04 distance sensor trigger signal on 2.5 V 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 3 V (nominal) Coin Cell.
The HC-SR04 is getting a ...
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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 ...
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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 ...
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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:
...
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Counting up/shifting right, counting down/shifting left 4164 DRAM addresses using TTL/CMOS
I'm working on a design that uses 4164 (64kb x 1 bit) DRAM with 8 addresses (0-7), and I would like to be able to utilize a TTL/CMOS counter or shift register to make the data output count down/go in ...
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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?);...
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What is the quiescent power dissipated by a TTL totem-pole output stage?
In High-Speed Digital Design by Johnson and Graham, the quiescent power of a TTL totem-pole is given as:
$$P_{quies} = \frac{0.4I_{sink} + 1.0I_{source}}{2}$$
I am fairly certain the 1.0 is a mistake ...
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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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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-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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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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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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What is "level of saturation" for transistors?
This is a term I've never heard of, and it's presented on a work analysis of a ttl nor circuit. It basically says that the transistor that links the output with the ground should have a higher "...
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Optical pulse sensor not producing a clean TTL pulse
I have two of these optical pulse sensors monitoring LEDs on my electric and solar meters - Optical Pulse Sensor - Github
The first sensor outputs nice TTL pulses at 5V, the second sensor outputs ...
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DC>DC Isolated Converter (ADuM5401)
I'm in a bit of a quandary as to if I've approached something the right way or if there's an obvious solution I'm missing.
(Sorry for lack of schematic, still WIP).
Goal:
Self-powered isolated USB >...
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LTspice and TTL logic gate parameters, my edge triggered ramp generator is current starved? How to correctly estimate TTL gate impedances?
Continuing with my edge triggered ramp generator and its simulation, thanks to all your help I have the LTspice simulation set up that I can see a theoretical circuit work that uses the rising edge of ...
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Chip shorting to ground when connecting the grounds
I have a pcb that converts USB to RS232, it is using a CH340G and a MAX2323. The output when not connected works as expected.
I try to connect it to a separate device that has its own power supply. ...
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Need to step down votage to test a heart rate monitor
I'd like to create a test bed for heart rate monitor devices. The type of monitors I'd like to test use chest straps to detect the voltage fluctuations caused by the heart. I'm told this votage ...
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Safety considerations (for parts) for a beginner building with expensive parts
I'm building for the first time (for me) a circuit with an expensive part (a $80 DEC J11 CPU) and would like to know some "safety" tips so I don't inadvertently destroy the thing while playing with it....
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What happens if the output of a 74LS05 IC is connected to the input of a 74LS04 IC?
Explain what would happen if I connected the two ICs?
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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 ...
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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 ...
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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, ...
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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) ...
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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 ...
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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
...
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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 ...
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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 ...
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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 ...
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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 ...
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