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4k views

Why is my circuit so incredibly sensitive to electric fluctuation?

I recently finished building a circuit showcased in a beginner’s electronics book. I have included the picture of my creation below because I think it may become relevant to the question. At the ...
20k views

Choosing resistor values for non-inverting amplifier and why?

The gain here is A = -Rf/Rin. However, lets say I want a gain of 10 V/V. Which resistor value would you choose and why? I know that you could have infinite number of combinations for these resistors ...
702 views

Why are low-dropout (LDO) voltage regulators unstable?

LDO regulators based on P-type transistors seem to be the preferred form of linear voltage regulator today, but I keep hearing about how I have to choose the output capacitor(s) carefully to guarantee ...
3k views

Conditional stability

I'm learning about op-amps and feedback and how feedback affects their stability. I've been reading about gain and phase margin and their uses when I came across this: I don't quite understand ...
10k views

Stability problem in unity-gain opAmp

As a part of a controlled power supply for hardware-in-loop testing for a student driven project, I had to develop a current buffer (voltage follower) which could source up to 1 A. I had the (bad) ...
7k views

Gain margin and Phase Margin Physical Meaning

I have been trying to understand the physical concept of Gain and Phase Margin.From what I understand it a relative comparison around the critical point (-1,0) which when converted to magnitude and ...
3k views

Does this voltage regulator use “on-off” control, or is it a voltage follower?

In Electronics A2 (GCE), we are currently studying voltage regulators. An example voltage regulator circuit is provided using an op-amp and a power MOSFET. I would judge this to be a voltage ...
7k views

Converting and Stabilizing output voltage of a dynamo hub

Preface - I don't know much about electronics :P I have ordered a Shimano dynamo hub for my bicycle. I have done a little homework and here are my findings about it: The output of the above ...
1k views

What components or circuitry exist that can provide extremely high speed, accurate clocks?

I've been curious for awhile now about doing some high speed projects, such as measuring time differences of radio wave reception, and was wondering if there exists components that provide clocks much ...
5k views

High-stability oscillators (non-crystal)

Are there any high-stability oscilators, which are not crystal based, given that temperature is stable down to 0.01 C and voltage down to 0.001V? Will LC-based oscillator be able to show performance ...
452 views

Choosing a Tantalum based on Min. ESR - LDO Stability

How does one go about choosing a capacitor for a LDO regulator which specifies a min. ESR? Capacitor datasheets that I've seen only contain the Max. ESR parameter. One could just choose a cap with a ...
45k views

How to determine a system is stable using pole zero analysis?

To my knowledge, as long as the poles of the transfer function are in the left half plane, then the system is stable. It is because the time response can be written as "a*exp(-b*t)" where 'a' and 'b' ...
1k views

How to know whether the bandpass filter is stable

I am designing a bandpass filter using MFB. However, I do not know whether my filter is stable or not. Can anyone give me some criteria or methods to evaluate the stability of the filter design?(still ...
221 views

Understanding resistors on inputs/outputs of op amps

I was looking at the schematic for Dave Jones' uCurrent, and I can't seem to make sense of why there are 270 ohm resistors on the inputs and outputs of the op amps in his circuit. The resistance is ...
777 views

Does MEMS accelerometer stability deteriorate over time?

I am wondering if over time MEMS accelerometer produces any worse output than when it is new? I found this research paper which acknowledges that temperature affect sensor output but there are no ...
82 views

Diode Clamp failing with LDO Circuit

I'm back with yet another mystery. Summary question: Why would an input to a voltage clamped circuit de-stabilize and or elevate that voltage clamp's upper rail? How do you properly clamp voltage ...
702 views

OP07 unity gain

Is an OP07 unity gain stable ? I am powering it with a +/- 5V supply. I am using it to buffer a DC signal which varies slowly. Most of the modern Op-amps have their datasheets mentioning them ...
1k views

Is it ok to clip component leads after soldering?

When working with through the hole components, I have read that you should clip leads before soldering so the shock from clipping doesn't break the joint. On the other hand I've seen a ton of ...
309 views

Why 60% overshoot with 55° phase margin?

UPDATE: Based on the answers I received, I got this working beautifully. There's a full outcome report in one of the answers below. I'm working through the design of an electronic load, basically a ...
553 views

Can there be “too much” capacitance on a buck regulator output?

I've an MPM3610 buck regulator module with an integrated inductor of 0.47 µH and a fixed internal compensation. It employs constant-on-time regulation. The datasheet gives some application ...
2k views

How can I stablize an analog to digital reading?

I've built a clock out of a PIC16F877, some LEDs and other stuff... To set the time in 5 minute intervals, I'm using a 22K ohm potentiometer connected between GND and +5V with the contact connected ...
794 views

Why is this oscillator unstable?

I designed a simple triangle wave oscillator based around a switchable curent soure. It works for a few cycles, then it becomes unstable and finally stops working altogether. Why is this? If anyone ...
212 views

Can a 7805 ever oscillate?

I see many references to input and output caps helping with "stability" and some outright references to preventing oscillation in both answers on this site, and even in some data sheets. I also have ...
1k views

Why is my op-amp oscillating?

I am attempting to build the following circuit using an LM6171 op-amp. I know that this op-amp is unity-gain stable. I previously had this circuit working with an LT1637 op-amp, but I had to switch ...
246 views

Phase margin analysis of a [diy] PMOS LDO [with LTspice]

I'm somewhat familiar with using LTspice to do phase margin analysis for a classic i.e. obvious negative feedback path opamp circuit; in fact I've done that analysis successfully for fixing real opamp ...
503 views

Alternative ways to maintain temperature stability of silicon BJT circuits other than feedback resistors

So I've been messing with Bipolar Junction transistors lately and I'm trying to really nail the concepts of designing circuits with these things cause I want to start using them in some of my circuits ...
184 views

Why do we take gain and phase margin from these points in stability?

In the following graph, why do we take the phase margin from -180 degrees and the gain margin from 0 dB in stability?
200 views

Effect of zeroes in system stability

Suppose we have two third order systems (a and b), with three poles and two zeroes,poles for both the systems are at the same positions in frequency domain but these systems differ in the placement of ...
139 views

Delay and Stablity in Negative Feedback Systems: Confusion

Below is a block diagram that shows an op-amp in negative feedback with feedback network made from resistive divider: The encircled block is Op-Amp with 1 and 2 as its inverting and non-inverting ...
141 views

Systems stability with zero poles

I have a rather simple question I would say. I know that systems having real poles to the right side of the plane will inevitably be instable (for LTI systems at least). But I'm confused with ...
129 views

Observer Based Control System Design

Consider the discrete-time system described by $$x(k+1) = \begin{pmatrix}0 & 1 \\ -2 & -3\end{pmatrix}x(k) + \begin{pmatrix}0\\1\end{pmatrix}u(k)$$ a) Find a feedback state vector that ...
123 views

Force amplifier into oscillation

The Minicircuits RAM-8+ amplifier has been replaced by the pin compatible RAM-8A+ part. The old RAM-8+ part was conditionally stable and I had to use an extra output attenuator after the amplifier to ...
100 views

How do I determine $R_o$ for an op amp?

I understand that when driving a capacitive load with an op amp, the output resistance, $R_o$, of the op amp interacts with the load capacitor to form a low-pass filter, introducing a pole in the ...
2k views

Stability and loop gain of negative feedback systems

When we look for stability of a feedback system, why do we only concentrate where loop gain is unity and check the phase margin there. The phase of the closed loop system might be passing through 180 ...
865 views

How can you guarantee stability of an inverting opamp configuration amplifier?

I had to design a circuit for measuring the voltage of a negative power supply rail (-15 V) and feeding it into a ADC (0-3 V DC-coupled input range). This measurement is only used for diagnostics and ...
2k views

9V AC stabilizer

I've got a power supply: IN: 220V AC OUT: 9V AC 1A Note that the output is AC, not the conventional DC output. It has no regulation systems built in (simple transformer). I'm looking for a ...
1k views

I understand that having an capacitive load at the output of an op-amp can potentially make the circuit unstable. However, how can I go about calculating this? For instance, I'm trying to design a ...
113 views

What can be inferred from the frequency an op-amp is oscillating at?

For whatever reason, I seem to create a lot of oscillators in the course of developing circuits involving op-amps. I'm wondering if the frequency of oscillation, which normally appears to be quite ...
386 views

Coil-less AC-DC line regulator

I'm trying to fix an AC-DC line regulator that I have build and doesn't work as expected. I'm trying to convert AC 220V mains to DC 5V 10mA without a transformer. To do this I'm using an 1uF 250VAC ...
2k views

Powering 28 LEDs in series by 220VAC - simple stabilizer

I have a home-made thingy that I would like to use as a lightning in my living room. It contains 7*4=28 LEDs (red, 1.86V, ...
71 views

Open loop oscillating

Will an open loop op amp with negative phase margin oscillate? I understand phase margin is defined in closed loop transfer function with equating denominator to zero . But will an insufficient ...
614 views

What does it mean for amplifiers to be stable only down to N gain, where N > unity?

This is related to What's special about "unity-gain stable"? which is about unity gain stability. But what exactly does it mean if some op-amp is said to be only stable to, say, gain ...
329 views

Initial states in a digital system with more than one stable state

Let's say I have a digital system of basic combinational logic with feedback (I do). That is, the value of the gates' inputs depend in some way on the value of their outputs. Depending on the ...
228 views

Load capacitance estimation for compensation of switching power supplies

I'm calculating a compensation network for power supplies based on the LM20323MH from TI. I have slight doubts about correct estimation of output capacitance to use in the calculation. The board is ...
361 views

Given bode plot, determine the poles and zeroes

Ultimately, I want to figure out the transfer function $$H(s)$$ But to know that I would need to know where the poles and zeroes are. Looking at this, I know $$H(20j) = 0$$ but that's pretty ...
155 views

Unstable points in a basic memoryless circuit

I have been told that there can be more than a single solution to a circuit, and that some of those solutions might be unstable. As a simple example, a resistor with a constant power source, connected ...
134 views

Meaning of zeros in transfer function

Can someone please explain, provide a link or cite a book where the properties of the zeros for continuous and discrete time systems are explained? I know that the zeros are the frequencies where the ...
104 views

AP5002 step-down switching regulator loop stability

Problem, parameters I have an 5V output power supply, with 2S LiPo input (6-8.4V), implemented with AP5002 (PWM control 2A step-down switching regulator, docsheet), and for the life of me, I can't ...