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8
votes
4answers
594 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 ...
7
votes
4answers
447 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 ...
7
votes
5answers
2k 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) ...
6
votes
4answers
880 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 ...
6
votes
1answer
1k 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 ...
5
votes
3answers
2k 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 ...
5
votes
2answers
278 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 ...
4
votes
2answers
266 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 ...
4
votes
1answer
366 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 ...
3
votes
4answers
553 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 ...
3
votes
1answer
75 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 ...
2
votes
2answers
194 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 ...
2
votes
1answer
348 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 ...
2
votes
3answers
790 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 ...
2
votes
2answers
631 views

Op-amps and Capacitive Loads

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 ...
2
votes
3answers
214 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 ...
2
votes
1answer
190 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 ...
2
votes
1answer
218 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 ...
2
votes
1answer
125 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 ...
1
vote
2answers
253 views

What happened when P controller's gain equal zero?

For example, I use Routh-Hurwitz Cirterion to examine the following system with P controller gain K: \$\frac{{K\left( {2 - s} \right)}}{{{s^3} + 3{s^2} + 5s + 3}}\$ I closed loop it with H=1 and ...
1
vote
2answers
9k 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' ...
1
vote
4answers
139 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, ...
1
vote
1answer
2k views

Arduino alternate PWM input method

I'm working on a rudimentary flight stabilization system for an airplane, which reads in 4 PWM inputs from an R/C receiver. The problem is, the pulseIn command is taking far too long to execute, so I ...
1
vote
0answers
56 views

Forming Nyquist Plot from magnitude and phase transfer function graphs?

So the solution is present above, but I'm having issues understanding the Nyquist Plot. So here's what I know from the magnitude and phase graphs: At \$\omega = 0\$, \$G = |\infty|\$ At \$\omega ...
0
votes
3answers
80 views

Securing a pcb to be used in a keyboard to its case

I'm looking for a way to secure a pcb I will be making for a cherry mx (homemade) keyboard to a case which I'll also be making. Obviously, I don't want the pcb to move. I could use standoffs/screws, ...
0
votes
2answers
329 views

Vanilla crystals stability

I wonder which of commonly used crystals in PC have higher short- and long-term stability, in stable temperature & voltage environment? Crystals I commonly see there are: 32kHz watch crystals ...