Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [input]

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

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

Current, electromotive force, or power supplied to an electric circuit, network, or device.

Computer Science Information put into a communications system for transmission or into a computer system for processing.

502 questions
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Add a passive hardware token using a 3.5mm jack

I have a box that I made for my niece, which allows her to exchange voice messages with me. It is powered by a Raspberry Pi and features two buttons, a LED, a microphone and a speaker. Now, for Christmas I want my niece to be able to exchange these…
Besi
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How do I extend the number of analog (input) pins available to me?

I already know how to extend the number of digital pins on an Arduino using a multiplexer. I want to increase the number of analog input channels that I have. One solution is to add another Arduino as a slave. How would I increase the number of…
Manishearth
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Considerations when using internal pull-up/down resistors

I am working with STM32 micro-controllers. These micro-controllers have the option to set the input pin as pull up or pull down: Earlier I used to give external pull up or pull down resistor wherever required but now I am wondering whether I can do…
Whiskeyjack
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Why does most test equipment have 10 MΩ voltage input impedance?

I'm only speaking for equipment interesting in voltage measurements. Multimeters, oscilloscopes and conventional lock-in amplifiers seem to have mainly input impedances of 10 MΩ. I understand the need for a high input impedance to stop drawing of…
BlackPenguin
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opto isolated arduino input

I want to protect a pin with an opto isolator to get an external signal from an electrical meter (35VDC max, 50mA max, 240ms pulse width). The purpose is to count the pulses. Do you have some schematics examples for that ? Thanks
hotips
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12 V input on 3.3 V GPIO, TVS pulled down or Schottky pull up?

I am building my own PLC that has to accept permanent inputs of up to 30 V DC into a STM32F with 3.3 V inputs. The switched input will have to work with 8-30 V, but 90% of the time the input voltage will be fixed at 12 V or 24 V. Inputs will only…
Newbie Noob
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PCB "Touch" Button

Is it possible to use a PCB pad as a button? I think of using it to switch on a curcuit that is only supposed to be enabled, when the user holds it in its hands. As inspiration, I used the pads that are being used on soft touch buttons on keyboards…
mxcd
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Can unconnected inputs make an IC get warm?

I am using an ATF16V8 PLD for some simple glue logic. While testing it on a prototyping board, I noticed that it gets warm to the touch almost immediately. I checked that no outputs were short circuited, but I also knew many inputs were left…
NeonMan
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Is this clamping voltage divider for a high-impedance input a good, robust design?

I have an AC input as follows: Can range from ±10V to at least ±500V continuously. Runs from roughly 1 Hz to 1 kHz. Needs > 100 kΩ of impedance on it, otherwise its amplitude changes. May occasionally be disconnected and subject the system to ESD…
JohnSpeeks
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Input voltage range of opamps

I understand that, for an ideal opamp, Vo is bounded by Vee and Vcc (i.e.; Vee < Vo < Vcc). But, what about the input voltage range? What is the allowed input voltage range in which opamp works normally? Can we apply Vn and Vi voltages which are…
hkBattousai
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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 at any pin" constrain that depends on the input…
vicatcu
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What is a "dry contact input"?

I'm a PC software guy, a newbie to electronics. Recently, I've got a project in which I need to source for a DAQ that can provide dry contact inputs to an interfacing digital output controller. The controller generates alarm signals. I've…
Joshua
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How is this 5-24V input circuit working?

Since I require some kind of wide range input (going to a microcontroller) for a new project, I looked through some designs that are already in use (or were considered at some point) for other products in my company. I found this circuit, which…
Rev
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What is the use for non-inverting input resistance in a negative feedback opamp?

Here in the Figure R5=50K. This resistor value is not in the equations to obtain output voltage, and in many tutorials non-inverting input is directly grounded without a resistor. What might be the reason to use it here?
user16307
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How to implement a "rotary switch" like in audio equipment?

for my current project I'm planning to use an input "device" like this in the photo (don't know its real name): It is used in a lot of musical instruments and it is like a potentiometer that can be rotated as many times as you want. I think it…
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