1. roci75

    2k potentiometer

    Hi guys, I bought a 2k ohm 10 turn potentiometer, I’m trying to use it with arduino analog pin. The problem is that when the pot gets to a certain value the arduino turns off (I think it might be the over current protection). I have allso tryed to use a op amp as a buffer before the analog pin...
  2. roci75

    Op amp not working as expected

    Hello guys, I bought an op amp from mouser, the LMP7721 (data sheet below). I have been testing it, I soldered it to a break out board. after connecting 3.3v supply from an arduino uno to v+ and v- and connecting in- to vout I measured between ground and in+ 1.2 to 1.8 V. if I disconnect vout...
  3. E

    Help this complete and utter newbie get an op amp voltage follower working

    Hi everybody, I'm taking a beginners DC circuitry course and I'm trying to learn on my own time about analog circuitry, something which has fascinated me for a while now. One of the things I'm trying to start with is, as the title states, a voltage follower, since this is (supposed to be) a...
  4. M

    Designing a functional function generator using op-amps

    Hello everyone, I'm currently having some trouble over a lab practice in which I was required to build an op-amp based function generator. The primary requirement is to generate square and triangle waves (varying their frequencies through potentiometers) using LM-741 IC's. Initially, our...
  5. L

    Square wave oscillator based on comparator AD8611

    Hi, I need to create a square wave oscillator with variable frequency upto 200 MHz and (optionally) variable duty cycle. I've got several components for this: a comparator AD8611, an operational amplifiers AD8009 and AD8055. I tried mutiple circuits, but it didn't help. Could someone please...
  6. RagTMS

    THAT1512 alternative for DIY Microphone project

    Dear all, This is a repost since the original post (https://forum.allaboutcircuits.com/threads/that1512-alternative-for-diy-microphone-project.188951/#post-1760251) was in the wrong section This is the project I am trying to recreate I'm looking for a way to make the preamp created in this...
  7. J

    transistors out of saturation in an op amp

    Hello, what would happen if, in my operational amplifier, some transistors are not in saturation at a certain input voltage? I find it quite hard, nearly impossible, to maintain tall the transistors in the saturation region for every input voltage, some of my transistors leave the saturation...
  8. xaxxa

    overshoot and stability issue

    Hello, I have designed a two stage op amp with a phase margin of 63° ( with a compensation capacitance) which is sufficient to ensure good stability of the circuit. However, I still have a huge overshoot problem when I use it as a follower. How is it possible if my circuit is stable and how can...
  9. StijnC

    Single op amp PWM generator

    Hello, I have to design a single op amp circuit that has only +15v, -15v and GND as input and outputs a symmetrical PWM signal (+V and -V) with adjustable frequency and duty cycle. I have something that works partly but not completely, I can adjust the duty cycle from ±60% to ±100% but af that...
  10. J

    Op amp output different from calculated?? Any help appreciated!

    Hi all! I am new in op amp, and currently studying the basics of it.. So I designed this LM741 circuit with a single supply, I made the input at the V+ to be 1.5v supplied by a voltage divider, and a gain of 3 with feedback resistor being 20k and R1 being 10k. My problem is, according to the...
  11. sbya1875

    Noise Parameters and thier effect on Filter design

    Hi everyone, I was designing a filter and my team wanted to ensure the total noise to be as low as possible and hence searched for low noise op-amps. I'm actually having a problem with the term Input Voltage Noise Density, like for AD8605, the datasheet mentions Input Voltage...
  12. xenon_eleven

    Active Butterworth Bandpass Filter unexpected peak

    I am currently trying to design a bandpass filter in a simulator for a university assignment to the following criteria: Frequencies below 1KHz and above 250KHz should be attenuated. Note that you will need to calculate the cut off frequencies given the pass band (1KHz to 250KHz) should not be...
  13. B

    Need help AC coupling push pull amplifier with op amp

    I have an AC input of 0-5V that i need to go from -2.5 to 2.5V. this will then go through an op amp and then trough a push pull amplifier configuration. I just cant seem to find a value for the capacitor that will work, so if someone could explain where im going wrong that would be greatly...
  14. Arjuna1

    Adding Voltages

    I am working on detecting fingers being placed on guitar frets. My idea is to run a small voltage through each of the strings, a different voltage for each string. The player touches the string and makes the string touch the fret. On the end of the fret I detect the voltage with a...
  15. R

    DC biased opamp input resistor function

    http://www.generalguitargadgets.com/pdf/ggg_dist_plus_sc.pdf I'm looking to understand this schematic. Currently focussing on the input and power stages. Here's where I'm at: INPUT R1 is a pulldown resistor. It provides a path for the leakage current through C2 when the switch is in the...
Top