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2answers
45 views

Amplifier Audio Ground to Signal Ground

I am using a VS1053 (on a SparkFun Music Maker shield) to provide audio for my project. I am taking a line out signal and inputting it into an op amp for signal processing, ultimately being input to ...
1
vote
3answers
67 views

Modification on a sine wave before ADC

I actually have an Arduino Due board, with everything working on it, using the ADC and the DAC. For my input for the ADC I need to have a signal 0-2.2V but my signal is actually between -5V to +5V. ...
1
vote
2answers
60 views

op-amp outputs supply voltage on GND Signal

I am trying to use an op-amp (first time). I know the basic theory of its amplification circuits. To test I am using an Arduino Nano Microcontroller to create a Signal (0-5V). I want to amplify the ...
1
vote
2answers
102 views

Converting a variable frequency to TTL HIGH and LOW levels, based on a fixed (possible non-fixed?) frequency

I have a square output from an LM324 op-amp (0 and 5 volts) which has a frequency between 1 to 500 Hz (yes, low frequencies). I would like to find a simple way to have HIGH TTL signal when it is over ...
2
votes
0answers
101 views

PWM to synth control voltage improvements

Just built this little circuit to control my Moog Werkstatt. The plan is to make a MIDI-to-CV converter and add more CV outputs and of course a GATE output later. But before going further, I thought I'...
1
vote
2answers
80 views

How to calculate Op Amp's gain using Arduino's ADC

Hi, I'm feeding a 500 Hz PWM signal to the Op Amp's V_IN using Arduino DUE. The Op Amp, which is ADA4000-2 from Analog device, is connected to +12V, -12V using an external power supply. The power ...
0
votes
0answers
47 views

Op Amp Unity gain gives an unexpected constant saturated output

I have this following circuit; I use an Arduino DUE to send a 12-bit DAC output and I want to feed this in an Op Amp. Every ground is tied to the same ground. The Op Amp is ADA4000-2 from Analog ...
0
votes
3answers
154 views

Correct use of op-amp to amplify photodiode in reverse bias

So I have a photodiode in reverse bias, from which I intend to measure my pulse. Currently, my schematic looks as follows: simulate this circuit – Schematic created using CircuitLab Weirdly,...
0
votes
1answer
101 views

Correct use of transimpedance amp

So I realized that it might become a necessity for me to use a transimpedance amplifier for a pulse watch that I intend to make. Some background: The pulse watch shoots light at 940 and 660nm at ...
0
votes
3answers
62 views

Constant Current Load fails to recover after setting load to zero

I'm trying to design a Constant Current load for testing battery cells using the TLC070 Op Amp (what I happen to have on hand) and a low pass filtered (150Ohm + 470uF cap) PWM input from an Ardiuno. ...
0
votes
2answers
132 views

LM324 with arduino as a differentiator for phototransistor signal

I want to measure the rate of change of voltage with respect to time coming out of a phototransistor, and preferably amplify it at same time, as the change is not so significant. But lets just not ...
0
votes
1answer
59 views

How would I go about measuring an analog signal that has both positive and negative voltages on an arduino analog pin at a high sampling rate?

I have a signal that fluctuates between -70mV and 50mV. How would I get the arduino mega to read this on an analog pin at a high sampling rate? Ultimately I am trying to graph the data in real time so ...
0
votes
2answers
119 views

Why are my op-amp (LMC6484) output signals not independent of each other?

I am using a quad op-amp (LMC6484) in a non-inverting circuit. Using only one of the 4 op-amps I was able to amplify Vin = 80.3 mV to Vout =1470 mV. Rin=2.66k Rf=10k. V+= 9V… V- = -9V My problem is ...
0
votes
1answer
243 views

Sound Chip Audio Amplification Circuit YM2612 + TDA1308

I've been working on a project for connecting a Yamaha YM2612 to an arduino and triggering sounds to be played from the chip. I'm having trouble on the audio part of the circuit. I've worked out a ...
0
votes
2answers
194 views

Amplification of sinusoidal signal from filter circuit

Intention of the project is to obtain sinusoidal signal generator of frequency range 10Hz to 100Hz and 5v signal from microcontroller i.e arduino uno, using pwm from arduino uno I got the square ...
0
votes
1answer
28 views

Non-inverting amplifier input voltages are different, related to limited output range?

I'm calibrating a pressure sensor and recording output voltage with an Arduino and the non-inverting circuit (recommended in the sensor manual) shown below. Without a load on the sensor (R_flexiforce),...
-1
votes
1answer
306 views

AGC (Auto Gain Control) Circuit Clipping Problem

guys once again back with a problem to my AGC circuit, however this is the last one. The problem is the LM833N is clipping around at less than 1.92Vpp at a 4.586V Vcc, I understand this op-amp isn't ...
0
votes
1answer
315 views

Photodiode + OpAmp + Arduino: Further Amplification

In order to measure the concentration of a methylene blue dye in water, I am using a 660nm high power LED and a photo diode with op amp setup as described here. (schematic below): I have tried two ...
0
votes
1answer
124 views

Auto Gain control circuit idea

I am trying to make an Auto Gain control circuit. Having any input source's voltage the same. For example my latop outputs around 1.36Vrms @ 1khz and my iPhone outputs around 0.962Vrms @ 1khz ...
1
vote
1answer
264 views

Arduino inductance meter using op-amp as comparator?

I want to create an Inductance meter with an arduino nano, for that I follow that link whose theory convinced me : tutorial (The Diode on schematic remove analog negative voltage, Edit: I have ...
0
votes
1answer
159 views

circuit for mesure positive & negative voltage + Vref resolution

i would like to make a "voltmeter" to read from +2V to -2V and connect it to an Arduino ADC ( 0V to 5V ). I found different configurations for do this job: From this site: Bipolar to unipolar ...
5
votes
4answers
735 views

Amplifying pulse signal (0.1 .. 0.5V) to Arduino digital input

How this can be so difficult (to me :-). The incoming sensor signal rests close to 0 Volts and gives ~ 0.5V pulses, which needs to be read by Arduino digital input (interrupts). So far, what I have ...
3
votes
2answers
423 views

Scale and Shift Analog Voltage with a Single Op Amp?

I am looking to map the output voltage from the onboard DAC of an Arduino Due from its raw range [+0.54V --> +2.75V] into the new range [-10V --> +10V]. I will use an op amp with -12V and +12V power ...
0
votes
0answers
68 views

Digital spikes on analog ground

I am working on a mixed signal box used for digital-analog conversion, and have a weird problem. I encounter digital spikes on analog ground, even when the box is turned off. The spikes are around 1....
0
votes
1answer
65 views

Op-amp for audio-arduino interfacing circuit

Is it possible to use opamp of LM392 in this circuit for interfacing audio to Arduino? I had LM392 laying around so I tried it, but it doesn't work, the output is always exactly 2.50V. I am not sure ...
1
vote
0answers
170 views

Audio op amps - what do they do to the audio I hear from the speaker?

I have a simple DC circuit which outputs audio from a ESP8266 attached via 2 wires and a NPN transistor to a simple speaker. It uses this library : https://github.com/earlephilhower/ESP8266Audio/ to ...
0
votes
0answers
374 views

Circuit Design for Temperature Sensing PID Controller using Op-Amps

Basically, the idea is that I'll have a temperature sensor (LM35) that will sense the temperature of a certain metal can. This metal can is subjected to heat by a gas burner, and the gas burner's ...
1
vote
1answer
111 views

What kind of signal processing circuitry do I need to generate a line level output on an Arduino?

I am trying to create an Arduino based music synthesizer. How can I safely generate line level output (+/- 2 volts centered at zero, with a frequency range from 20Hz-20KHz) from my Arduino using a ...
0
votes
2answers
377 views

Simple EEG circuit is not working

My simple EEG circuit is not working. For a simple test I built my EEG circuit on a breadboard and wanted to see if it works before adding filters and moving it to perfboard. I used an AD620AN and a ...
2
votes
3answers
331 views

Single supply op amp to convert 0-5VDC to +/-2VDC (microcontroller to line level)

I am generating a 0-5 volt sine wave using an arduino with a DAC. I would like to level shift this signal (DC bias?) by -2.5 volts and have a gain of .8, so that I end up with a line level sine wave. ...
1
vote
3answers
860 views

Why high impedance source in ADC input causes error?

Recently, I had a problem with two sensors (LDR and LM35), when I tried to read them in Arduino ADC, both measures were totally wrong. Searching in the internet, the answers are related with high ...
0
votes
1answer
641 views

Current Measure on 230V 50Hz

I want to make a power meter which I can plug in a electrical socket in my house. I tried around with falstad to measure the current over a shunt and came up with this solution. But the problem is ...
4
votes
2answers
305 views

Transimpedance amplifier with inverted output

In a little hobby project I am trying to send data from one Arduino to another using a modulated laser and a photodiode. On the sender side, the laser has a dedicated modulation input for up to ...
1
vote
6answers
386 views

How could I amplify the output from this UV photodiode sensor

I have been able to use the following photodiode sensor board to detect changes in the output of the sensor when a UV plasma is active. However, changes sensed when the UV plasma is active are very ...
0
votes
1answer
296 views

Arduino controlled audio amplifier gain?

I've building a preamplifier that also functions as a headphone amplifier. When no headphones are present, the gain of the internal opamps should be 1x (unity), so that the signal can be passed out ...
1
vote
1answer
146 views

Is this circuit correctly protecting my Arduino I/O pin?

I'm quite new to electronics. I thought of this circuit to prevent more than 5V from going into the Arduino I/O pin. Should it do the trick or is there something wrong? simulate this circuit – ...
1
vote
4answers
4k views

How to measure line voltage (220V) with an arduino?

I'm a Electrical Engineering student and I want to sense and sample the voltage signal coming from a wall socket (110V - 220V). I came up with the following circuit using a voltage divider with high ...
1
vote
1answer
233 views

what protection is required between op amp and 5v adc?

I've created this small circuit to translate voltage drop over a shunt resistor into a usable range for arduino (5v atmega32u4) adc. This is to measure current out of and into (charging) a 12v ...
0
votes
2answers
638 views

photodiode circuit setup

I'm working on a spectrophotometer for a physics project. I've figured out the monochromator already, so for the detector I decided to try a photodiode circuit. This being my first experience with ...
0
votes
1answer
383 views

Help with basic transimpedance amplifier circuit

I'm a physics student and doing a project where I need to detect moderate intensity of light with a response as linear as possible (measuring angles using Malus law (linear polarization)). Anyways, I ...
0
votes
0answers
974 views

using opamp with arduino

I have a circuit like below in which the photodiode is connected to opamp via a capacitor and resistor The purpose of the opamp is to convert photocurrent of photodiode to voltage (Vo) than this Vo ,...
0
votes
2answers
200 views

How does the feedback of this op amp works? [voltammetry]

I am trying to build an Arduino version of the voltammetry thing described in this paper. Before questions here is a little background for those who don't know what voltammetry is. This device works ...
-1
votes
1answer
441 views

How to make a AC current source of variable low frequency and variable low amplitude

I want to make a pure AC Sinusoidal current source with variable frequency(2 Hz to 6 Hz) and variable RMS value(2 mA to 6 mA). I am using Arduino to generate sinewave and for controlling the output. I ...
1
vote
3answers
2k views

Envelope/Peak Detector

I am working on a project in which we are trying to design and build an ultrasonic thickness gauge that will calculate the thickness of a given part based on the time difference between sending a ...
1
vote
1answer
847 views

DIY sourcemeter

I have been wanting to make a fourpoint probe setup for a while. I posted a question about it here and some people told me about operational amplifier constant current source and the non-inverting ...
0
votes
1answer
2k views

What is the maximum force that a FSR sensor can detect?

Force Sensitive Resistor (FSR) is a sensor which lowers its resistance when there is force upon it. If there is no force acting on it, the resistance is ~10MOhms. In the datasheet of FSR A401 of ...
0
votes
2answers
462 views

How to level shift + / - 1V waveform signal to 0 - 5V

Currently I am trying to build a portable ECG device where by the ECG signal will then be sent to Arduino UNO where the data will be transmitted via Bluetooth and the waveform will be displayed on ...
2
votes
2answers
875 views

I designed a constant speed PWM motor driver using an op-amp and mosfet. Will it work? Can you point out some problems?

I'm currently working driving two motors using some sort of PWM or switching such that they run at constant speed, regardless of load. I want to control this entire circuit using one Arduino PWM ...
2
votes
2answers
158 views

Using piezoelectronic components as position trackers

I've been trying for a while to get this circuit working, I looked all over the place and now, defeteated, I come to the point where I need to ask for help with my specific case. My plan was to use ...
4
votes
4answers
842 views

Interfacing dual supply op-amp with microcontroller

I have an dual op-amp amplifier circuit (LM833) to amplify a signal with a +-10V dual-supply rail from a 22V supply with a resistor voltage divider. The output is rectified into a 0-8V output, for ...