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Questions tagged [high-impedance]

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6 votes
4 answers
997 views

Implementing guard trace/ring in PCB design for opamp having high impedance input

In the circuit below I am trying to create a "guard ring" for the opamp with high input impedance (~1T Ohm) to avoid femtoampere current leakage. I'd like to ask you guys if I did it right. ...
Phạm Sáng's user avatar
0 votes
2 answers
104 views

How to change the levels of a logic signal [closed]

I'm looking for a component that can translate voltage levels from 3.3 to 5.0 V (LVTTL to TTL). This component will be placed in order to spy on a signal, it must therefore have a high input impedance ...
MisterElec94's user avatar
2 votes
1 answer
223 views

Tri-state input to three logic states

I'm looking for an IC or small circuit that implements the following truth table: Input Output 1 Output 2 H H L L L H Z H H Is this possible? The purpose is to keep an SPI SS signal pulled high ...
inc's user avatar
  • 85
2 votes
0 answers
33 views

Sampling high impedance, higher voltage source

I have a low voltage ADC. How do I sample a high impedance signal that has a voltage higher than my ADC can handle? I understand the concept of buffering the ADC input to deal with the high impedance ...
Matt Thomas's user avatar
3 votes
2 answers
91 views

What kind of switching system can I use for a massive array of high-impedance electrodes?

My application: I am attempting to create a device to map redox potential in soils at ~1 mm resolution, using a grid of platinum electrodes. Background: Redox potential is a measure of the "...
user278411's user avatar
1 vote
1 answer
43 views

Attenuator impedance is not the expected value at higher frequency

I have recently made a High Z (1 MΩ) attenuator with R1= R3= 8.75 MΩ, and R2= 243 kΩ. I am using an LCR meter to test the impedance at higher frequencies. At frequencies above 50 kHz, the impedance is ...
Chadi Harmouche's user avatar
2 votes
2 answers
171 views

How to level shift bidirectionally with a high impedance output state?

I have communications bus I am trying to reverse engineer. It is based on a 9600 bps UART but inverted so it sits at 0V when idle, and pulses at 5V to send a binary 0. Unlike a normal UART the TX ...
Malvineous's user avatar
  • 1,795
0 votes
1 answer
141 views

Can I use a 50 Ω attenuator with a high-Z scope?

In my project involving the measurement of current using a Pearson current transformer, the instructions specify the use of high-Z (1 MΩ) oscilloscopes. Given the need to attenuate the signal, I have ...
Shakiba HS's user avatar
3 votes
3 answers
440 views

Is there a circuit to detect if a line is high-impedance?

I was wondering if it was at all possible to detect a high-impedance state. I intend to use it with a LS245 within a register. It should essentially be able to turn on an LED (bring the output to HIGH)...
Aiden K's user avatar
  • 39
11 votes
7 answers
4k views

Has anyone measured what a high-impedance pin looks like?

I understand that when an IC pin is in a high-impedance state, the pin is not connected to anything internal. It will be at the voltage to whatever it is being pulled from the outside. I am just ...
user avatar
5 votes
4 answers
2k views

How can I differentiate between high and high-Z state?

I'm using this MCP73831 device. I want to know how what to expect as a voltage level on the STAT pin when the below chart on page 13 says, STAT = HIGH & STAT = HIGH-Z. When the charging is ...
user avatar
1 vote
1 answer
367 views

How do I optimize my op-amp "guard ring"?

I'm trying to measure the moisture content of wood via a resistance measurement. The moisture content range I'm trying to measure is in the order of 1 MΩ to 1 GΩ, so only ~5 nA current at 5 V DC. The ...
kyotee89's user avatar
0 votes
2 answers
77 views

Treating a high-Z input as both high and low at the same time

Setup (not strictly necessary to answering the problem; supplied for the curious): I have a single logic output pin from a device, logic 0 = 0 V, logic 1 = pulled high to Vcc through a 10 kΩ resistor. ...
Arby Bellie's user avatar
3 votes
2 answers
565 views

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 ...
Steve Schnepp's user avatar
1 vote
0 answers
89 views

Why is the voltage across high impedance indeterminate?

The analog pins on my Arduino read sporadic values when unconnected, and my multimeter (set to VDC) shows random values when there's no connection between the probes. If I connect the analog pins on ...
glibg10b's user avatar
  • 217
0 votes
2 answers
1k views

How does an Instrumentation Amplifier reduce DC offset?

While researching different current measurement methods, I came across a particularly interesting circuit which has a very high input impedance and apparently reduces the effects of the input offset ...
A.H.Z's user avatar
  • 633
0 votes
0 answers
139 views

STM32G0 Seems to output 0.77 V on the input pin when set to high impedance and nothing else is connected to it, why does this happen?

Currently I have an a pin on an STM32 set to be an input and floating (high impedance). When the device it was measuring from was powered down and nothing was going on I was measure about 0.35 V on ...
user9964422's user avatar
1 vote
0 answers
264 views

High impedance voltage source measurement with ADC

I would like to measure voltage coming from a photodiode in open-circuit condition. The measurement is OK with classical digital voltmeter, but with an ADC internal (SAR) or external (Delta-Sigma) on ...
Marcel Pasquinelli's user avatar
5 votes
6 answers
2k views

Difference between no input and a zero input in digital electronics

I'm new to digital electronics and try to understand how logic gates works. In books many times Zeroes​ and ones are referred as Low and High respectively, is Low and High used as an indication of ...
user215805's user avatar
  • 1,184
2 votes
2 answers
92 views

Voltage divider high resistace

I need to build voltage divider to measure the battery voltage (7.3V) using max 3.3V ADC. As the device most of the time spends in the sleep mode (<1uA), the current drawn from the battery should ...
0___________'s user avatar
  • 2,594
0 votes
2 answers
45 views

Smallest Footprint Source Only (No Sink) Buffer Solution [closed]

I'm currently in the process of designing a cable snake cable tester for recording studios that involves testing for connectivity between a large number of inputs. This involves using a ...
Emmett Palaima's user avatar
1 vote
1 answer
190 views

Why an does an offset on the reference electrode create an offset on the measure electrode of a pH probe?

I am making an analog front end for a pH probe. I encountered a design where creating an offset on the reference electrode creates an offset on the measure electrode. How does that work? Does the ...
Damezumari's user avatar
3 votes
1 answer
143 views

Removing high impedance ground pours parallel to signal traces in Altium

whenever I route parallel traces on Altium, I get those narrow ground pours between my signal traces when I fill my ground planes. A collegue told me: since these pours are narrow and thus high ...
JCSB's user avatar
  • 287
0 votes
2 answers
2k views

CAN Stub node termination in a network - 9.28k resistor

In a CAN network, the ends of the network has to be terminated with 120 ohm - I understand this. The middle node in the below diagram is the stub node and it does not have to be terminated, my stub ...
Nidhi's user avatar
  • 87
0 votes
3 answers
1k views

Circuit that can switch between Vcc and High-Z

I want to develop a switching circuit (for controlling power, rather than digitial signals) that is able to take an input and switch between Vcc and high impedance, rather than switching between Vcc ...
rutloj's user avatar
  • 11
0 votes
1 answer
86 views

Multiple differential tranceivers on single bus

Im using a few moduls of rs422 tranceivers connected on single bus Easy module has transciver with TX input, RX output power end differential pair output and input - but no EN pin to hold the ...
Ron Vaisman's user avatar
0 votes
4 answers
3k views

How is high impedance state physically different from a logic low state?

I have read this question and the answers that follow on the electrical stack exchange but I still face a difficulty in understanding the practical difference between high-Z state and 0 state. It is ...
Shashank V M's user avatar
  • 2,331
2 votes
3 answers
3k views

Microcontroller Unused pins Configuration

I am having this microcontroller - S32K142 64 pin 5V core voltage I have a few pins which I don't want to use. While checking the datasheet of the Microcontroller, I couldn't find any information ...
user avatar
0 votes
1 answer
160 views

Effect of high impedance Opamp buffer on current lost

In the below figure, end-user have the choice to output 4-20mA or 0-10V (using MUX control by uC), I have inserted high impedance buffer(The part number is not correct) with the voltage divider to ...
Shahreza's user avatar
  • 539
1 vote
1 answer
260 views

disagreement between theoretical calculation and measurement of upper cutoff frequency of a circuit based on RG58 coaxial cable

For a 100 meters RG58 coaxial cable, according to the datasheet, the capacitance of the cable is 10 nF and the inductance is of 25 µH approximately. A sinusoidal voltage is applied at the input of the ...
moumi Lelion's user avatar
0 votes
0 answers
29 views

Measure high impedance with low internal impedance device

I was given this thought by one of my co-workers (we're both still novices when it comes to electronics). Background: we have a device with a small internal impedance and have to measure a high ...
Frontsky's user avatar
2 votes
3 answers
3k views

When is a wire considered high-Z?

I need to make sure I understand perfectly the high-Z state and its relation to voltage.I intend to explain what I have understood based on three example, is there something wrong ? Let's consider ...
JackOfHearts's user avatar
1 vote
1 answer
223 views

Calculate Voltage Seen at High Impedance Pin

Background I am designing a simple lamp dimmer circuit for use with a 450W bulb for the purpose of heat fusing various synthetic materials. I have the basic dimming functional but now I am ...
MysteryMoose's user avatar
1 vote
1 answer
325 views

Buffer / Line driver ; 3 state IC Working

I am just curious to understanding the working of this - Buffer IC (Part Number - 74AHC1G126) My questions : I figured out that this IC does not act as a level translator which changes the voltages ...
user avatar
0 votes
2 answers
196 views

How does TXS0108E keep it's outputs at high impedance given it's internal block diagram?

I am trying to understand the block diagram of the TXS0108E bidirectional logic shifter. In the chip's description it says When the output-enable (OE) input is low, all outputs are placed in ...
user13267's user avatar
  • 621
2 votes
4 answers
1k views

Buffers output load in unpowered state

Lets take under consideration a 3 state buffer, such as this one: Since the datasheet doesnt provide the information about the internal build of the buffer, I was wondering either it is safe to ...
Łukasz Przeniosło's user avatar
0 votes
1 answer
3k views

Basic of a charged piezo : pC/G, mV/G, Signal analysis

This is the first time I use a High impedance piezo sensor and the problems went pretty quickly. Here is the piezo I used : Manufacturer part number : PKGS-00GXP1-R Rating : 0.35pC/G (+/- 15%) ...
Christophe Gudlake's user avatar
1 vote
2 answers
531 views

Tri State/Floating Signal Detection

I'm working on a project for automotive environment in which I need to read signals from the power mirrors switch in a microcontroller. The power mirrors switch controls the mirror's moving directions ...
Roga's user avatar
  • 35
0 votes
1 answer
360 views

Connecting logic gate input pin with pull up resistor to another driver input pin doesn't keep the voltage

I have a circuit with logic gates that implements a function in order to get 3 logic control signals. This logic works with 12V or 0V for high and low states. Logic input pins will be connected to ...
Suvi_Eu's user avatar
  • 851
1 vote
1 answer
267 views

Turning a high impedance output state to a concrete voltage value using a pull up resistor

I have this switch datasheet. I also have a connector with default pins arriving to switch D point. S points are connected to another circuit point. Note: D side connector is an output connector ...
Suvi_Eu's user avatar
  • 851
0 votes
2 answers
310 views

Inverted high impedance / pull down circuit

I'm devising a circuit to control the shutdown input on an integrated circuit. The IC accepts a high impedance input (can't be pulled to any voltage) to enable operation, or it can be pulled down to ...
Niek's user avatar
  • 101
1 vote
3 answers
610 views

Driving a high-impedance load from a BJT base

Are there any caveats with tapping off the base of a BJT to drive a high-impedance load, such as a logic gate or op-amp? In the schematic below, I have an open-collector output from ...
higrafey's user avatar
  • 343
1 vote
0 answers
361 views

high input impedance circuits

Working with circuits to get high input impedance. This is to capture signals while introducing as little interference as possible to the preexisting circuit, to load the source as little as possible. ...
pjn's user avatar
  • 41
3 votes
2 answers
349 views

Shift register Tri-State and ULN2803A

I was planning to use the SN74HC595 shift register in association with the ULN2803A and MIC2981 to switch on and off some loads based on the data of the shift register. What happens if I disable the ...
Fredovsky's user avatar
  • 391
0 votes
1 answer
2k views

How to design a high impedance buffer circuit?

How can I design a buffer circuit that takes an input of +/- 10V and scales it down to a 0V to 5V. The idea is to design a circuit that is microcontroller compatible (can be read by an analog-in pin ...
Britt Kelly's user avatar
0 votes
2 answers
80 views

Connecting Difference Amplifier to High Impedence Sensor

I have a high impedance differential sensor (stable 600k impedance Rth, 10mV signal, Fout=1kHz). I need to amplify this signal to about 1V (40dB gain). Due to layout/system constraints only the ...
EasyOhm's user avatar
  • 4,669
-1 votes
1 answer
1k views

getting outputs in simulation as all high impedance. topic: restoring algorithm for binary division

I am getting outputs of my hardware as all high impedance (ZZZZZ). i tried synthesizing the code and got these warnings. I think there might be a problem in the test bench i am trying to run. ...
Eris Drater's user avatar
-1 votes
1 answer
350 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 ...
user186493's user avatar
1 vote
0 answers
263 views

OPT301 Photodiode Output Measurement

I am working on a setup where OPT301 is fed with an optically filtered light output yield a very low current which is then Current to Voltage converted by integrated op-amp within the device, but the ...
Ashish Sharma's user avatar
3 votes
3 answers
3k views

High impedance in RTL Verilog

I am designing a shift register. It has a control signal called RD which is asynchronous (so I can't use it inside the procedural block). The whole point is my n-1 ...
Dig_Verif_bee's user avatar