Questions tagged [ttl]
Transistor Transistor Logic. Logic circuits built from bipolar transistors and resistors.
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Output voltage level of TTL gate
The output voltage level of the TTL logic family is from 0 to 0.4 volts (LOW) or 2.4 to 5 volts (HIGH). Suppose we have a TTL inverter with a square wave of 5 volt amplitude as input (0 volt and 5 ...
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TTL bus termination physical circuit layout
I'm breadboarding a simple data bus terminator for a 1970s TTL computer bus that was normally unterminated. I'm trying both passive and active termination to see how they work, but have a question on ...
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How to use SMA port for RF Switch's TTL Control?
I am considering purchasing this RF switch from Eravant (previously sage), and I realized many of its SPDT RF switches are using a SMA female port as the control logic input to the TTL driver, whether ...
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Understanding passive TTL termination
I've been working with 1970s devices and an unterminated system bus. I am adding termination to that but want to first understand a circuit that I have seen to make sure I understand what's going on. ...
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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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Load bootloader on ESP32
I'm trying to load the bootloader to my esp32 or that's what I think I need, because when I connect it with USB to TTL, and I connect TX with RX, Rx with TX and GND with GND and I reset the micro by ...
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Driving a 12-to-24 V P-channel MOSFET with TTL
I'd like to control up to 16 motorized valves with an ESP32. I'm using 74HCT595 shift registers (5 V outputs, 3.3 V input logic) to drive 12 V relays via NPN transistors. But the relays are pretty ...
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Create TTL pulse with button press
Is there any way to get a 5V TTL signal (pulse of whatever duration, could even be a boxcar) from a button press with a very simple circuit or with some consumer device?
I need this to do some ...
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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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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.
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Interface higher voltage signal to 5 V pull down input signal circuit using discrete hobby components
I have a microcontroller, TTL logic that expects its input to be connected to the ground via a brake lever to tell the microcontroller that the brake has been applied. I believe it uses an internal ...
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Definitions of Serial TTL UART MCU acronyms
I was looking for a comprehensive list of terms and acronyms concerning serial peripheral communication including their descriptions and, crucially, how they relate to each other. Since this site ...
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TTL NAND gate analysis
I was looking into Millman's Microelectronics book, 2nd edition, pp. 245 - TTL NAND Gate.
I am a beginner in electronics and was looking into this book just because of an assignment problem about a ...
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Debugging a problematic old TTL pull-up that's not pulling up
I am trying to bring back into operation a late-70s disk controller board (all 74xx TTL). I'm stuck trying to figure out why a small pull-up network is resulting in a far out of spec voltage not doing ...
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Is AM29F040B CMOS EEPROM TTL Compatible
I can't really make any sense of the datasheet regarding whether the AM29F040B EEPROM can be used with TTL inputs, so wanted to ask on here.
It is a 5V CMOS IC, but there are mentions in the datasheet ...
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Differential capacitance change measurement (sensing) with 74LS628
I'm researching the possibilities to accurately register the capacitance changes of a big metal plate (area 10 m2) to the ground (GND, yes - earth, soil). It varies around 100-200 pF.
For now I'm ...
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Serial conection HMT310
How to connect the HMT310 via serial port? When I connect it and open PuTTY and put "?" for it to show me the data, it pulls all "U"s. I already checked that the baudrate and other ...
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TTL to RS485 using MAX485 - Capacitor voltage requests
I need to implement a TTL to RS485 converter into an home made project and searching by Google I found this module with related schematics:
Could you help me by indicating the correct voltage for the ...
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Why does the 74LS08 see an input logic level even if the inputs are not connected?
I have an 74LS08 (AND gate.) I did not connect any inputs to the IC, but it gives me voltage at the outputs. Should I separate VSS?
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What is the correct maximum value for resistor R₁?
How do I calculate the maximum value of resistor R1 if the following values are known:
VDD = 5 V
inverter CMOS CD4069UB
IIL = IIH = 0 mA
VOH = 4.95 V
VOL = 0.5 V
IOH = IOL = 0.6 mA
VD = 1 V
maximum ...
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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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