# Questions tagged [input]

Something put into a system or expended in its operation to achieve output or a result

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23 views

### ESD Input protection on low Vmax digital inputs (3.6v)

I have a microcontroller monitoring a few digital inputs. The max voltage on these inputs is VCC + 0.3v. VCC is 3.6v so these inputs can't be higher than 3.9v. These digital input are just switch ...
80 views

### How to protect input against both ESD and reverse polarity?

I need to protect an external input on a device against both reverse polarity and ESD (IEC61000-4-2 +-8kV). The normal input is +5V dc at 100-200mA; the reversed input could be -5V and that should be ...
62 views

### What does an U244B IC’s input voltage do?

I’m new to electronics and I’m trying to connect a U244B ic on a breadboard. One pin says it’s an input voltage (pin 7). It works without anything being connected to the input and with battery ...
40 views

### timer input capture for really low frequencies

How low of a frequency can a timer be used to measure an external signal in "input capture" mode? If I need to measure something that has a frequency of say 1hz - 2hz... or even slower for that ...
110 views

### What is meaning of active low input in combinational logic circuits?

I am currently doing self study on combinational logic circuits. I encountered few terms like active low output, active low input. I understood what active low output means (putting not gates at ...
3k views

### Where Does VDD+0.3V Input Limit Come From on IC chips?

There are a variety of integrated circuits that specify that their input voltage can span a fairly wide (absolute maximum) range, e.g. -0.3V to 6.0V (ref, pdf page 4), and then have a "Input Voltage ...
59 views

### NVG compatibility LED Lights

For an avionics application I need to make a keypanel which has NVG compatible LED lights behind its keys. I am trying to understand how does the NVG compatibility (Night vision Goggles) relates to ...
46 views

### Interconnect 5v - 3.3v

Is this correct to connect 5v outputs and 3.3v inputs ttl logic via an open drain transistor and an internal pull-up resistor on the digital input? I suspect the 5v part can influence to the 3v part ...
22 views

### Input range for TPA311x

I'm reading through the datasheet of the TPA311x family. I'm looking for the input range for pins INPR and INPL but I cannot find this information. I see the absolute maximum ratings, but it's not ...
37 views

### What is input to the RF power amplfiier (gate of the MOSFET)?

I have read that the RF PA is a block just before the antenna. So, the input to the RF PA (voltage signal at the gate of trasistor in the PA) should be a modulated signal and thus the PA just does the ...
46 views

### Consequences of leaving unused inputs of clock buffer floating. Alternative: best practice

I'm using a Si53342-B-GM Original datasheet download at silabs for the si5334x-series as a clock buffer. In some cases I only need to distribute a single clock signal and in some of my cases I ...
69 views

### How does the logic board know the buttons have been depressed on the Philips ACC2330 foot pedal? [closed]

Unlike other input devices like an Xbox controller, that has the buttons physically mounted to the logic board, this foot pedal's logic board has absolutely no apparent connection to the buttons. How ...
71 views

### Contact Closure over distance

I have a contact (pushbutton) that's about 10 metres away of a Raspberry Pi. However; it behaves quite erratic and would trigger when for example an exhaust fan is started in proximity of the wire. I ...
74 views

### Are these input jacks the same?

Apologies for the dumb question. I am wondering if these two input jacks the same. Here's a stereo 1/4" jack designed for a guitar with active pickups: https://www.realparts.com.au/electronics/jacks/...
14 views

### Connecting balanced output with unbalaned input using adaptor

I want to connect my audio interface (balanced TRS jack output) with guitar pedal (unbalanced TS jack input) and I wonder if this kind of adapter will work: https://www.amazon.com/dp/B001JYSMV0/ref=...
23 views

### Combined 25V/OPEN and 25V/0V Input circuit

I am designing a board for digital inputs in which I will be receiving 2 types of inputs, 25VDC/OPEN and 25VDC/0V, 10 inputs each. The input signals have different specs but is it OK to design same ...
42 views

### Connecting balanced low impedance output with unbalanced high impedance input

I want to send the signal form my audio interface to the guitar pedal effect. I'll use interface's line out balanced output and plan to plug it in to the effect pedal which has high impedance ...
117 views

### Is it a good practice to use resistors for MCU inputs for this case?

I want to use Arduino Uno or a Nano which uses ATMEGA328P as micro-controller. D2 is now set as INPUT. During the start up I want the MCU to detect whether pin D2 is HIGH or LOW depending on the ...
71 views

### STM32F4 input capture

How can get input capture values from STM32F4 for measuring the duty cycles of the four different signal? Here is one channel code: ...
122 views

### Burned Up Trace on Input Cap

I'm working on a fairly simple PCB that interconnects three arduinos. There are also MOSFETs for switching some solenoids. The system runs off of a 24V DC power supply. I was running a LM7812 voltage ...
60 views

### ESD protection diodes on audio inputs / outputs?

I'm building a digital audio device with 1/4" stereo in and outputs that connect to a CS4272 codec. I'm wondering if and where I should place esd protection diodes. Pictured below is the analog part ...
53 views

### When using mA on analog devices, does the other wire go to 0V or Earth?

On the Schneider analog input module (link) we have IC, IV, IS, 0V and Earth terminals for a single channel. I've seen people connecting the signal wire from a transducer to the IC terminal and the ...
45 views

### Input of BLDC motor

Among the brushless DC motor, is there a motor with two input wire? I thought that bldc motors with hall sensors should have 2 input, but it was hard to find such one. Is it wrong concept about bldc ...
68 views

### Can I Use a Transformer to feed a Mains current to a RPI GPIO pin

I have a standard mains (240v) motion detector that activates an outdoors lamp. I want to notify my Raspberry Pi when the lamp is activated. My plan is to use a 240v to 3.3v transformer that I have ...
104 views

### Pic Programming - Nested Loops

I'm having some problem with my code and I can't get my two loops working properly. I'm new to C programming so I might have got the basic loop concepts wrong. I've got 10 LED lights connected to my ...
44 views

### Eliminating power-on state changes caused by input signal fluctuations

I have a circuit that uses several comparators to read an analog input signal and control some downstream digital logic. When the device powers up, the logic states fluctuate because the input signal ...
51 views

### Voltage source & current input

I am working on a project where I have a current source (analog output from a PLC) controlling a VFD. Based on the position of the dipswitch, the VFD will accept either a current or voltage input. The ...
40 views

### Allowing different inputs without needing to alter gain every time; a situation for a pre-amp?

The goal I am attempting to make a small diy bookshelf speaker system using 2 16ohm, 25 watt speakers and a 2x25 watt class d amplifier board. If it matters, the amplifier board is a class d amplifier....
161 views

### Optocoupler Characteristics

In my application I need to isolate a PWM signal @ 1 kHz, which is generated from a Beaglebone Black microcontroller. In my signal, I want to have one hundred different steps in duty cycle (from 1% to ...
38 views

### Comparator resolving input voltages close to vdd

I have a design problem to solve. The problem statement goes as follows: "Design a clocked comparator resolving input voltages close to vdd dissipating less than 100 uA". What does "resolving input ...
338 views

### Amplify an Electret Microphone using an input Jack 3.5mm

First time on the platform, I will try to be as clear as possible, and electronics is a hobby for me, so I'm open to any welcommed criticism. I'm trying to build a little project, recording the sound ...
255 views

### Op Amp input protection

I was looking for an Op Amp input protection circuit and the most common I found looks like this. When the voltage at Input Signal goes above/below Op-Amp's supply ...
63 views

### Motor/MOSFET Does NOT React To Input On Breadboard

So I have tried so many different variations on breadboard of this circuit but the motor seems to just be powered by the power rail on breadboard. It does not react to any change in the input and ...
55 views

### GPIO Configured as Input OR Output

Is it possible to identify looking at the schematics whether a GPIO pin is configured as Input or Output pin for the case in following image? PIN93 and PIN94 of a MCU are connected directly with ...
124 views

I am new in the automation industry, and now I am focusing on learning how to wire correctly analog inputs in detail, since last time I tried I damaged the module input because of wrong wiring. Here ...
42 views

### Calculate input resistance of power amplifier

how can I calculate the input resistance of this circuit? Thank you!
49 views

### What's the use of the 4 outputs of a power entry module (Qualtek 864-10/009), and how to interpret it's circuit digram?

Main question: What is the purpose of having 4 outputs? If I only had pins 1 & 4, I would be able to use 115VAC when it's set to 115VAC, and 240 VAC when it's set to 240VAC. For 240VAC setting:...
69 views

### How to find the output voltage of a system with a computing amplifier?

I got a question regarding the following system. The only given value is the input voltage $$U_e = 8V.$$ Now the task is to find the output voltage $$U_a.$$ My question now is how do I find this ...
229 views

### Difference between input current and supply current?

I am reading and trying to understand datasheet of ICs. I am reading this datasheet now : http://www.ti.com/lit/ds/symlink/sn74hc00.pdf In the table 6.5, there are two parameters namely Ii and Icc. ...
103 views

### Signal conditioning for piezo shock-sensor digital input

I have a piezo element glued to a piece of material, and I want to get a digital signal (to drive an interrupt on an Arduino) when something strikes the material. So, there's a certain noise floor on ...
62 views

### What happen to a dff(flip flop) without input?

I have this question but I don't know what happen to a dff without an input is it always 0 ?? like this picture below the 2nd dff hasn't any d ??? Also, if someone can draw the answer of the question ?...
505 views

### Identify Vintage Power Cord for 1980s Organ [closed]

I Recently acquired a Technics SX-C600 organ but it needs a power cord. Does anyone know what type of power cord I should get for this? My understanding is that this is a rare organ.
58 views

### op-amp pin is sitting at high voltage (active low-pass filter)

I am looking at using the OP1177 to act as an active low pass filter. I need to smooth out a 20kHz signal burst with a minimum of 50 cycles to reach a voltage on the output to interrupt an ...
32 views

### Noise on Input Buttons for H-Bridge

I'm constructing an H-Bridge to control a linear actuator. I've done so by using a 2-channel relay module, some buttons, and a ESP32. I do not believe this is an issue of debouncing as I account for ...
51 views

### Measuring 24V AC input state with microcontroller

I need to measure the state (on/off) of a 24V AC line that is currently powering a solenoid valve. The microcontroller will take over the control of the solenoid through a solid state relay, but I ...
1k views

### Voltage across LED and source when LED is floating from one end

Refer to these pictures and can you explain why is there 3.335V coming across LED and the LED isn't even turning on. Also to note is that changing the resistor value does not change voltage at D2(A2) ...
456 views

### Input Impedance of a diode connected MOSFET

I was trying to derive the small-signal input impedance of a diode-connected MOSFET (figure included), and came up with this expression. Is my method correct? I have been reading about methods of ...
36 views

### designing load for the MCU to drive by output current

I am talking about a plain MCU (ATMega32, max 20 mA per pin) output asserting a logic line high or low. I.e. to drive this IC: http://www.ti.com/lit/ds/symlink/ads114s08b.pdf There is a table ...