As of May 31, 2023, we have updated our Code of Conduct.

# Questions tagged [analog]

Analog circuits have a range of voltages, rather than just two as in digital logic.

310 questions
Filter by
Sorted by
Tagged with
52k views

### Analog voltage level conversion (level shift)

I have a joystick that puts out analog voltage somewhere between 1.5V and 3.5V. I want to transform this range of voltage to control a motor controller that takes analog voltage between 0V and 5V. ...
• 221
16k views

### Designing a *linear* MOSFET driver stage

I'm looking for a MOSFET driver circuit that can be placed between an op-amp and a power MOSFET to operate the transistor as a linear amplifier (as opposed to a switch). Background I'm developing an ...
• 6,992
44k views

### Input impedance of Arduino Uno analog pins?

I'm using the ACS712 hall-effect based current sensing chip on some small robotic arm motors, and reading in the analog voltage with an Arduino Uno. I've had reasonably good results, but only after ...
6k views

### Logic level converter using Transistors

I am trying to make a logic level converter using transistor BC547. This is to convert Voltage level of Rpi Gpio from 3.3 to 5V. I have wired the circuit according to this diagram: I have done this ...
• 169
48k views

### How are positive and negative feedback of opamps so different? How to analyse a circuit where both are present?

In an opamp, feedback on the positive input places it in saturation mode and the output is of the same sign as V+ - V-; feedback on the negative input places it in "regulator mode" and ideally Vout is ...
• 9,547
1k views

### Analog analog multiplication, part of a hybrid CPU (for fun)

Short version: How do I make an analog multiplier that takes two analog DC inputs? Long version: I made a comment recommending Ben Eaters videos for another question, while doing so I ended up ...
• 8,118
8k views

### How do I sample a -2 V to +2 V analog signal with a PIC microcontroller?

I am using a PIC micro with a 10bit ADC to take readings from an analog signal with a frequency less than 300 hz. However that analog signal is in the range of -2 V and +2 V. How can I condition the ...
• 101
15k views

### MOSFET in reverse polarity protection

I have such a reverse polarity protection circuit for the power supply: The MOSFET used has a maximum VGS of 10 V, so that's why there's a Zener diode of 7.5 V. But what happens if I ...
• 1,557
10k views

### Why can current only flow in loops? [duplicate]

In the following image: Why can't current flow across the following wire? It's a simple question, but I've kind off always wondered. Thanks!
• 639
3k views

### How do we create current sources?

Constant current sources (simply, current sources) are useful and necessary devices. They are widely used to drive LEDs, charge capacitors and batteries, to bias differential amplifiers, etc. The only ...
• 12.7k
1k views

### Op-amp speed: bandwidth vs slew rate

I was learning about the difference between op-amp slew rate and bandwidth. Everywhere it says slew rate is a large signal parameter and bandwidth is a small signal parameter. I have few questions: ...
• 1,271
782 views

### Operation of tuned collector feedback oscillator

I am trying to understand the following tuned collector feedback oscillator extracted from here using LTSpice. I understand that L1 and C1 creates the resonance at the oscillation frequency and L2 ...
• 808
1 vote
384 views

### Differential vs non-inverting op amp advantage

Assuming I need to measure and amplify a voltage drop over a resistor that is connected to ground on one side (no negative voltages, since current flows always in one direction), is there any real, ...
• 1,619
4k views

### BJT amplifier (Vce) voltage!

I am a bit confused with the given information to me (written in Bold letters below). If i could get some more ideas and clarifications it would be really helpful. Given: BC 547 transistor (in use) ...
39k views

### Inverting buffer with op-amps

I know that it's easy to make a unity gain buffer with an op-amp (as a voltage follower): simulate this circuit – Schematic created using CircuitLab I also know that it's easy to make an ...
• 3,797
39k views

### how determine the RC time constant in PWM digital to analog low-pass filter?

I 'm looking for the best RC time constant and its reason in a PWM to convert digital signal to analog based on duty-cycle and frequency and other parameters. PWM frequency is 10 kHz.
• 371
18k views

### Is a square wave still considered DC?

Say I have a logic-level square wave, where 0V is "low" and 5V is "high". I'm pulsing this at a constant 60Hz, 50% duty cycle. My intuition says that since the voltage never goes negative, it's a DC ...
• 335
3k views

### Mixed signal PCB layout for PSoC

I am developing a PCB for an analogue sensing application. It uses the internal ADC on a PSoC3. As usual, the application is very space constrained (11mm x 21mm), so I have had to make some ...
• 26.8k
9k views

### Floating voltage-controlled resistor with LM13700: How does it work?

1. The LM13700 The LM13700 is an Operational Transconductance Amplifier (https://en.wikipedia.org/wiki/Operational_transconductance_amplifier) converting a differential voltage into a current output. ...
• 2,317
11k views

### What resistors to use to read several buttons with a single analog pin

EDIT: Thanks, all of you helped a lot! Ricardo summed everything up nicely so I'll mark his answer as the best, but all of the answers helped me understand. Thanks again :). I have an Arduino Uno R3 ...
• 183
12k views

### General impedance converter

Can anyone give an explanation about general impedance converter? This question might not be specific enough, but I will appreciate if someone could share as much as possible about this circuit.
2k views

### Why do we want higher power factor in ac motors?

Here is a simplified 3P electric motor below: This motor is simply combined of three coils facing toward to the rotator (in the center) 120 degree apart to each other. The user wants his rotator to ...
• 1,253
2k views

### Why does the collector current direction remain the same in saturation and active region?

The collector current direction remains same in both active and saturation state where the former puts the base collector junction reverse biased and the latter puts the base collector junction ...
• 2,403
1 vote
18k views

### What is the best way to get a sine wave from a square wave?

I have square waves of different frequencies (1KHz to 20KHz), and I need to convert them to a sine wave of the corresponding fundamental frequency. A RC ladder Low-pass filter was the first thing ...
• 79
1 vote
1k views

### Solving Unkonw R1 and R2 in classic descrete BJT bais arangment

im stuck solving the RB1 RB2 values is a classic discrete BJT circuit bias arrangement. Im sure its a simple thing that im just not seeing. Circuit values given are Ie=1.5mA V collector to emmiter =...
223 views

### Can this push pull oscillator improved for experimental realization?

I am using the following push pull oscillator circuit is extracted from this Application Note for implementation of a wireless charging system. In simulations, it's efficiency is above above 85% when ...
• 808
21k views

### Why does Samsung include useless capacitors? [closed]

I do component-level repair of tablet mainboards, and I have seen this puzzling situation on two different models of Samsung tablet mainboards so far (SM-T210, SM-T818A). There are ceramic chip ...
• 1,258
9k views

### Is analog signal arithmetic faster than digital one?

Would it be theoretically possible to speed up modern processors if one would use analog signal arithmetic (at the cost of accuracy and precision) instead of digital FPUs (CPU -> DAC -> analog FPU -> ...
• 487
4k views

### analog circuit design resource recommendations [closed]

What are some excellent resources related to advanced analog circuit design? This includes RF, sonar, audio, low-frequency, high power, low power, noise, amplifiers, etc.. To get the most obvious ...
22k views

### How can I slow down the switch time of a MOSFET?

I have an NMOS that is switching too fast for my application. Into the gate I am sending a logic-level square wave (PWM). Unfortunately for me, as expected, the output is also a near square wave. How ...
• 2,096
7k views

### Convolution perfomed by an analog circuit

As a Electronic Engineering student I have a fair knowledge about convolution and DSP. But, I was wondering if it is possible to perform a convolution only using analog circuit (without memory)? And ...
6k views

### What is the definition of absolute maximum ratings?

What is the definition absolute maximum ratings? Does it vary from manufacturer to manufacturer?
• 74.3k
2k views

### In below picture, is ammeter AC or DC? Is there direction for connection with load in series? If so what if I connect in wrong direction?

This is front view of analog ammeter. There are 2 terminals with nut and bolt behind it but nothing marked neither plus nor minus.
• 153
883 views

### BJT Puzzler: Common Emitter or Emitter Follower?

A few high-reputation members have disagreed on this in the context of other questions, so I thought I'd post it as a separate question. Question: Is the NPN BJT in this circuit configured as common ...
• 6,992
27k views

### Why JFET is called a voltage controlled device while BJT is called a current controlled device?

Why are JFET/FET called voltage controlled devices while BJTs are called current controlled devices. Both require a voltage to operate properly. In both an electric field is produced so what is the ...
• 681
11k views

### Converting PWM into an analog signal

I'm trying to think of the best way to convert a PWM signal into an analog signal. I could use an RC filter, but that requires a very high PWM frequency to create a faithful reproduction of the signal....
• 31.5k
2k views

### What is the input impedance of a differential amplifier?

I have this circuit: How would we calculate the input impedance of the differential amplifier? I have read answers that says that the inverting impedance side will just be R1=200 ohm. I have also ...
• 359
3k views

### Proper way of connecting logic GND / power GND on MOSFET driver

I am tring to build half bridge using IR21844 mosfet driver, i have read datasheet and design tips and some of the topics in this forum. The one thing i still cannot get is the separate GND pins ...
• 3,159
6k views

### 4-20mA to 0-3V3 Converter

Looking for a simple design to convert from 4-20mA signals to 0-3V3, I'm thinkin about configuration shown at picture attached. And I would like to discuss its suitability. It is based on: - A ...
• 367
2k views

### What's a reference text on analog design?

I'm looking for a intermediate text that covers (discrete) amplifier circuit theory using BJTs and FETs and circuit elements such as current mirrors, differential stages, feedback theory, etc. My ...
• 385
2k views

### In an ADC what are the units of resolution called?

I have a signal whose full scale output on the 12bit ADC is 4095. If I reduce the signal so I see the output number is (say) 4000 the output has decreased by 95. But 95 what? What are those divisions ...
• 13.3k
2k views

### Constant controlled power source

There are circuits for constant controlled voltage, and constant controlled current as shown below: Voltage controlled constant current source Voltage controlled constant voltage source simulate ...
• 74.3k
25k views

### Ultra low power/ simple flashing circuit

ideally I want this to run off coin cell batteries. I found a circuit that uses transistors and capacitors but the voltage requirements are higher than I want. Is there any way I can make this circuit ...
• 61
4k views

### Designing a stiff voltage source using an emitter follower

simulate this circuit – Schematic created using CircuitLab I am new to electronics, and I am trying to do Exercise 2.2, page 67 of The Art of Electronics. Use a follower with base driven ...
6k views

### How to mirror resistor? (use same variable resistance for multiple op-amp gains)

I want to create parallel op-amp circuits/channels and use the value from a single potentiometer to adjust the gains of each uniformly by making each op-amp see a 'copy' of the resistance to set the ...
• 475
1k views

### Stability of Constant Current circuit

we are developing constant current circuit with "High" current rate, about 3A. We are testing the second prototype, the circuit is this: Behaviour its ok, but we have observed, when we set high ...
• 43
10k views

### Need an optocoupler for getting directly proportional output galvanically isolated from the DC input

I want to use an optocoupler to linearly step down a DC voltage which willy vary from 0V to 400V. That is, I want the output to be directly proportional to the input and I want it to be galvanically ...
• 41
223 views

### Diode-connected BJT vs base-emitter BJT diode vs diode

I was having a look at the circuit design of Keithley 236 SMU. You can find this part of the circuit in the Keithley 236 Service Manual. Q47 is a BJT. Only the base and emitter are connected, which ...
• 153