An op-amp (operational amplifier) is a high gain analog voltage amplifier with differential high impedance inputs, and a low impedance output. A basic building block in signal processing, like as amplifier or active filter.

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How this circuit works?

Recently, i see such a circuit in a board schematic, but can't figure out how it works, why the first Op Amp has positive feedback ???? Thanks.
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26 views

Any good resource for MOSFET op-amp design?

I've been trying to design a two-stage op-amp for a week, but I haven't been progressing much. Does anyone know good resources that teach you how to design an op-amp (transistor level), preferably ...
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40 views

How do you calculate ICMR?

Let's say the Vdsat = 0.2V for M1 to M4, but 0.5V for M5. VT is 0.5. I think it's: ...
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2answers
146 views

What's wrong with an opamp as a voltage regulator?

I was watching a video about power supply design and it was mentioned that an opamp being used as a regulator like this: simulate this circuit – Schematic created using CircuitLab in ...
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2answers
64 views

How can I pull an op-amp output low without transients?

I am designing a simple 'junk box parts' adjustable constant-current dummy load. The following schematic seems to be the most promising design, where R4 and R3 are part of a current adjust ...
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1answer
62 views

What determines the operating point of an op-amp?

Let's say I have the following 2-stage op-amp: The DC transfer is as such: I would like the slope to be steeper and the center point to be at 0mV input. What should I be changing? In other ...
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197 views

High Voltage differential Measurement

Suppose I want to measure individual cell voltage of a 12-serial-cell battery pack, what would be my most economical options? Single cell voltage is 3V-4.2V but the stack can be between 2-12 cells ...
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49 views

Precision rectifier using a low-power single supply rail to rail op amp

Rectifying a very low voltage signal turns out to be very hard. (for me) I've tried this a few different ways without good results. I'm looking for a reasonable simple solution that performs well ...
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45 views

Explanation of oscillation occur in amplifier [on hold]

I have google all the information of why amplifier will have roll-off situation for higher or upper bandwidth of frequency, but all the information pointed to in order to reduce the occurring of the ...
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3answers
187 views

Operational Amplifier Adder

Please explane me why OPAMP is used in the adder circuit? why i can't add voltage without opamp? Anyway current doesn't go into opamp so it goes trought RF resistor ...
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2answers
39 views

Manual shows different settling time for an amplifier than its datasheet?

This transducer manual claims INA110 amplifier has 20 microseconds settling time: http://www.ohtegiken.co.jp/wp/wp-content/uploads/manual_zoc33man_1007.pdf But when I check the data sheet for the ...
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1answer
77 views

Unknown circuit symbol (“10 NP”)

I'm trying to figure out what the following schematic symbol is: I'm referring to the "10 NP" with the two vertical bars.
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94 views

Schematic notation for decoupling capacitor?

I'm wondering where this capacitor should be placed. Is it a decoupling capacitor? There are two supply rails on this particular op-amp, so I'm assuming that this indicates I need to put one between ...
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47 views

Distortion sine waveform from LT1227 amplifier

Schematic for the amplifier: Before connect it to amplifier circuit: Why the sine wave will distorted? any possible reason? is this due to noise? blue is the input signal of an amplifier and green ...
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2answers
68 views

Rail-To-Rail Comparator Design

I'm trying to detect small current pulses (~1.5mA). Currently I'm generating a ~20mV pulse on a sense resistor and feeding that to the input of an opAmp with some hysteresis. I'm having a bit of ...
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1answer
68 views

Circuit to provide 0-5 V output proportional to 0-30 A from C.T?

I want to design a circuit to protect oveload current of 30A.I have a controller board(PLC) which accepts the voltage range of 0-5 as an input and C.T with 1:7000 turns which can maesure 0.5 -60 ...
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132 views

Biasing a Non-inverting Amplifier

A signal that swings between -1V and +1V must be amplified with a gain of 2 using MCP602 and then biased by +2.5V, so it eventually swings between 0.5V and 4.5V. The amplifier only connected to 5V, ...
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50 views

High-current monitoring circuit

I have the following circuitry: Battery Supply => Current Monitoring Circuitry => DC Motors Battery Supply: 4AA NiMH batteries - 4*1.2V (1.5mAh * 4) Current Monitoring Circuitry: Max 4378 chip ...
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3answers
95 views

LM358 output voltage non-zero even though input is zero [closed]

I tried this experiment with LM358 and LM741. I used the circuit mentioned from this question: I have not connected any input source. But I am getting an output of 7.5V. I used R1 as 130 Ohm and R2 ...
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27 views

OPAMP common mode half circuit with its gain

I have a really complex circuit as shown: M4,M7,M14,M15 all pmos the others->nmos I am asked to draw common/differential mode half circuit. What I don't know: How to deal with M14, M15? Which ...
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2answers
64 views

Op Amp Decoupling with a Virtual Ground

I'm designing a low-frequency op. amp. circuit that operates from a single 10V supply. I'm using a TLE2426 "rail-splitter" to generate a virtual ground, 5V above earth ground, which is used as a ...
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39 views

Circuit to fix the amplitude of the sine wave

Does anyone have any idea on how to stabilize the various input amplitude of the sine wave for example 1.3V,0.8V to 1V of frequencies between 0 to 10Mhz? I known that a variable gain amplifier can ...
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0answers
55 views

100kHz active filter design

I am designing a basic 100kHz active bandpass filter using opamps (LF353). I am only interested in receiving the 100kHz frequency (might drift a few kHz) from my input signal. I have used a basic ...
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84 views

RF amplifier, why cascade two amp doesn't work?

I am currently working on a amplifier circuit on 8Mhz signal (around -40dbm). The amplifier is based on a IC chip (lm7171 bin). The problem is, the amplifier works perfectly for individually ...
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1answer
52 views

SMPS --> TDA8920 | +V GND -V op-amp

I'm thinking about buying a TDA8920 audio amplifier and power supply and I need some help buying the right PSU. See edit below. So here's what I know. L (AC) = Live (Brown*) N (AC) = Neutral (Blue*) ...
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3answers
59 views

Inverting Amplifier Not Giving Gain of -2.2

A LM358N op amp is used with R_f = 220k and R_i = 100k, which should give a gain of -2.2 in ...
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2answers
101 views

Choosing between active opamp filtering or an LC filter

This question follows a previous one I asked, where I accidentally achieved undesirable results from an opamp. Since then I have read up on active opamp filters (here and here) and refreshed my ...
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1answer
39 views

Comparator: What is appropriate for comparing ranges of about 50-100 mVs? Can I use an LM741 op amp?

I am attempting to create a high voltage signal when the voltage from a sensor I am using drops below a certain threshold, which will be between .05 and .1 Volts. I was trying to use an LM741 op amp ...
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1answer
91 views

Op-amp, Finding the V0

I have to calculate Vo in this circuit. Unfortunately I am very confuse how to do that. I know the current pass I(2ohm)= 0 and ix=0. I choose 5Vx as a super node and because ix=0 then the whole ...
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1answer
108 views

Choosing resistor values for Op-amp and inverting/non-inverting configuration

A LM358AN op-amp is choosen to amplify a AC input signal by a gain of 2.0. The input signal ranges from -1V to +1V and from 0 mA to 16.7 mA. The amplified signal ...
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2answers
98 views

Is it possible to run a photodiode plus op amp on a 3V battery?

Naive question here. I've been toying around with the idea of making a simple light meter. From what I've read, photodiodes generally offer the best sensitivity and accuracy (as compared to ...
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61 views

Gate resistor needed for this circuit?

I'm making a simple circuit for driving a fan based on temperature. Given that the LM339 needs a pull up (R5) do I need to put a series resistor in between the LM339 output and the gate of the ...
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1answer
58 views

Power opamp 'floating' output

So I had to design an amplifier with a 'floating' output. (I don't know if floating is the right word, it's the direct translation from dutch.) See the picture below ( I drew it whilst sitting in the ...
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55 views

Why does this voltage error amplifier output always reach its saturation voltage?

Why does the voltage output of both amplifier (Vm1 and Vm2 as shown in picture) always reach its saturation voltage?
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1answer
101 views

Amplifying and Reading a 0-1 V signal into Arduino

I'm trying to read the (0~1V) output of a current transformer (CT) into the 10-bit ADC input of an Arduino Nano. The CT is sensing the L wire carrying 120V at 60Hz. ...
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1answer
71 views

How are the gain and corner frequencies calculated for this speech bandpass filter?

This speech bandpass filter circuit appears in the TI OPA344 datasheet. It says "G = 100" and passband is 300 Hz to 3 kHz. How is the gain and corner frequencies calculated from the various ...
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2answers
115 views

Why does my opamp circuit give only x10 overall gain

I designed the circuit below after a suggestion that I use two gain stages rather than one large stage with an expensive opamp. This help keep the cost of my circuit down (the same application has ...
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2answers
83 views

Single supply 5V low noise hydrophone preamplifier [closed]

The title speaks for itself, I want to know if there is some circuit that provides low-noise, single supply operating at 5V and high gain to be used as a hydrophone preamplifier. The output of the ...
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1answer
108 views

Hardware of amplifier circuit

Output result of the circuit I have connected the circuit in hardware, but how come the output is like this?
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3answers
314 views

Can anyone explain this circuit to me?

I'm looking to generate a differential signal to control a laser projector's galvos, and as I understand it needs to be +5V/-5V (10Vpp). I've found this circuit for a laser harp, but I'm confused ...
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1answer
34 views

Multiplex based autoscale, question on simple circuit

I was looking for a clever way to automatically scale voltages from, say, 0-50V with a mux to an ADC (0-5V) without worry of damaging my inputs. My thought a simple amplifier with selectable gains ...
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4answers
122 views

Waveform generation with opamp

I need to design a circuit that generates the voltage waveform shown in the Figure 1 when an input voltage is applied as shown in Figure 2. Figure 1 and Figure 2 are in the second link below. Only ...
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2answers
69 views

Op Amp Input Offset

I previously asked about a light detection circuit and was set along the path of using a photo diode. I have a simple circuit created, now I need to create a null or offset so I can gain the PD at 0V ...
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0answers
76 views

Distance sensing with comparator

I want to implement a alert system using a comparator circuit. The circuit will alert the user when he is a certain distance away from an object of interest. The comparator circuit will comprise of an ...
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5answers
234 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 ...
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2answers
80 views

Solution for 20Vpp output waveform opamp [closed]

I am planning to design an opamp circuit from 2Vpp to 40 Vpp for frequency rage 0-5MHz as shown in the Figure: The problem I am facing right now is in the market, there is not an opamp chip that ...
2
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2answers
78 views

Howland Current Pump VS Wilson Current Mirror

I am interested on knowing what would be a better solution to create a current source for low current applications (below 20mA), an opamp based current source such as a Howland current pump (link to ...
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1answer
79 views

Using an op-amp for the first time

I am a beginner at electronics and recently, I was learning op-amps. I approached to making a battery full charge circuit using LM311. But the problem is, I do not know which pins of the LM311 are ...
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3answers
56 views

Determining peak to peak voltage of an NE5532 using an 8 ohm speaker

In order to calculate the peak to peak voltage of a an op amp (in this case an NE5532) I need to simply multiply the short circuit current from the data sheet (38ma for this IC in typical operating ...
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1answer
95 views

Can a digital pot and op-amp challenge the performance of a programmable gain amplifier

Currently I'm using a Microchip PGA for applying gain factors of 1, 2, 4, 8, 16 and 32. It's used in a design of strain gauge amplifier. The part number is MCP6S21 and I am happy with its performance ...