Help with OP amps Answered

I'm making an instructable about this circuit, it's a heartbeat detector, it's supposed to beep when a heartbeat is detected. Something weird is going on with the comparator, first of all, the input signal to the comparator seems to get "stuck" at the level of the comparator, like it is an invisible barrier that doesn't allows the signal to cross it easily, this seems to happen with and without the buzzer. Secondly, the comparator "rings", it doesn't displays a clean square signal when the threshold is reached, instead, at the end of the square pulse "ringing" appears. Removing the buzzer or speaker solves the ringing problem.  I tried replacing the buzzer by a 8 ohm speaker, but the problem persists. Then I tried changing the 1k resistor of the transistor by a 10k, but the problem is still the same. I don't know what could be causing this, bad design? A faulty chip? In the second picture it can be seen how the signal "bumps" an invisible barrier when reaches the comparator level, in the third the "ringing" can be seen, the fourth and last picture is how the (previous) comparator signal looks when the load is removed, the problem disappears. Thanks in advance,

Question by Victor805   |  last reply


OP-Amp Troubles

Hey everyone I was hoping someone here could help me with a problem in having. I've been tinkering with some op-amp circuits with the LM386N-1 namely the one I have pictured. I first assemble them on my prototyping station and they work well using the signal generator but when I connect them to a audio line from my computer nothing comes out the speaker I have tested the cable and speaker and they both work so I am at a loss as to what's not working. I would appreciate any help you guys can give me thanks

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PS3 Spec Ops

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Black Ops Guides

For this group, can I post my black ops guides too? (There aren't many places to find people who play black ops on instructables, you know?) So leave a response if your ok with it

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Hey this is where you can put your gamertag for Black Ops

Topic by DELETED_the vengeful aug   |  last reply


black ops cheats

Do you have any cheats for black ops If you do, Share them here! Step your game up... ...with cheats!

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mw3 and black ops

Hey people im starting a wii clan for black ops and mw3 you can do almost anything. the only requirement is to be active my name on both is DOUBLE0MEXICAN     (yes im mexican everone asks) black ops ally code:  2478-6346-3686 mw3 ally code:  2095-2297-2093 our clan name will be south part mexicans (spm) iv got friends from many different clans. i'v got a mic

Topic by jampie98 


Op-Amp Help

Hi- So, I made the circuit below to make sound-reactive blinky LEDs for a halloween costume (the round thing on the left is a condenser mic). I think I just got lucky that it worked, because I'm no genius when it comes to op-amp usage or design. Now I want to adapt it to control something else that needs a slightly higher voltage than the LEDs. Basically, I'd like the output to swing as high as V+ when the mic input is "loud" (a relative and possibly adjustable level). I've messed around with various resistor values as well as adding or removing resistors in places it seemed like it would help (according to the LM741 datasheet). All to no avail. Anyone out there who might know what to do? Again, I want the mic input to cause the output to go as hight as V+ (9V in this case) when it's loud, and be more or less at 0V when it's "quiet." Thanks in advance, _mykle

Topic by deadbilly   |  last reply



50uV to 5V amplification

How to amplify 50uV to 5V using LM324n op-amp

Question by Pranay ReddyK   |  last reply


operational amplifier

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Topic by justin.jackson   |  last reply


I want to make a scale with the circular guage and the little red pointer that spins how might this be accomplished?

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Question by undftdking   |  last reply


is the LM741CN op amp work same as the LM741 op amp? Answered

I'm making a distotion pedel and radio shack has the LM741CN but not the LM741C op amp.

Question by Flaky_Jay's   |  last reply


How many LED's would a TDA2822 op-amp drive? Answered

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Question by astroboy907   |  last reply


Ultra-simple low pass audio filter? Answered

Is there a way to create an ultra-simple low pass filter? Will not be using it for subwoofer, but to split audio and boost the power for audio-synced leds. Is a split at about 15-200 hz any good? or should it be higher/lower. Mostly looking for bass guitar and some drum to go in this area. I am totally non-audio knowleged, and am beginning my circuit building skills, so yes, i need lots of help. Can i hook this in parallel to speakers and will it not affect sound quality? can i use a separate audio (no op-amp) amp to boost power to leds? (such as a .5w amp to leds that consume less than .5w?) or should i find an op-amp. Could i just put the filter on and hook leds up in parallel w/out sound loss? I am getting totally lost. I know this is a LOT to ask of you, but your answers to my previous questions have been very helpful and are greatly appreciated. Thanks for putting up with me :) I wish i could figure this out better, but i am having a hard time. So far example no.1 on this link (about halfway down page) seems to look pretty good. Thanks!!!! http://www.electronics-tutorials.ws/filter/filter_2.html

Question by astroboy907   |  last reply


How Op Amps work? Answered

I was wondering if anyone could explain how an op amp like the LM741 works. I don't mean I want to know what's going on inside it, but more along the lines of "how can it be wired up?" and "what could it be used for?"

Question by tylervitale   |  last reply


op amp as comparator basics? Answered

Well... I'm making this battery charger cum level indicator, which should turn off the battery supply when its voltage drops below 10V. Im using an opamp as a comparator to do that. I have been scratching my head for 3 days but cant get this sorted. From what I have been experiencing for years, on an op amp if the potential on the in+ pin is higher than that on the in- pin, then the output pin goes high, else low. Right?  Now in this particular case (and the first time in my life) the ic gives 4.xx Volts on the output pin when in+ is higher than in- and 11.xx volts when in- is higher. Vcc is 12V.  Im bugged... I have attached the part of the Schematic that shows the IC and its connections. Please have a look. I haven't changed the IC yet, im doing that in a minute anyway. I'll mark this solved if the new IC does the trick. :)

Question by pro2xy   |  last reply


How to use an op-amp?

Hi, I've got an op-amp, the part number is OP07CP and I am trying to use it to amplify a voltage by around about 200 times. My set up is 6v going into a voltage divider with one resistor of 100ohm and a variable resistor of 10,000-50,000 ohm, so the output is 10mV-50mv. What I want to do is have the op-amp proportionally increase the voltage, so it goes to a voltage range of 1-5v, which an arduino can read. The power supply is  5v (from the arduino) and the powers both the voltage divider and the op-amp. For some reason, following the simple non-inverting op-amp configuration I just can't get it to work. Do I need a separate power source for the amp? I think it might have something to do with the fact that the amp's ground, input and negative are all just going to the arduino's ground. What can I do to fix it? If someone could help or even give me exact values and configurations of components that would be fantastic. I know that the amp and divider seem like a pointless complication if was just trying to measure the output of the variable resistor, but if you knew the greater extent of my project it would make more sense. Cheers

Question by makincoolstuff   |  last reply


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Question by spinynormann   |  last reply


I need OP-AMPS Answered

I am having a hard time obtaining old op-amps (max420cpa, ltc1150, etc). Maxim/Newark/(ebay -only seldom) no longer carry them. Where can I get them at a  REASONABLE  price? Thank You. Ed.

Question by edwianni1   |  last reply


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Hey everyone, I know it been a long, LONG, freakin time that I've been inactive. I have not posted any guns since the beginning of August 2012, but now I almost finished making a sniper concept. It is called the XPR 50, which is supposed to be a semi auto sniper featured in Call of Duty: Black Ops 2. This isn't a real gun now, and there aren't  any pictures of it in real life. I made the sniper from the picture in the black ops 2 game, which is in a really bad angle, with some parts of the gun distorted. I worked my butt off to make this, and this will be the first knex gun based on black ops 2. I didn't make the mag and the scope yet, so DON'T MENTION ABOUT IT!!!!!!

Topic by CODawesome   |  last reply


Basic Op Amp question

Hello, If the input to the positive terminal of an op amp is 12V, the input to the negative terminal is 10V, and there is no supply voltage, the output voltage is 2V and the output current is 0. Correct? Now, what I don't understand is what happens to the output voltage and current if I connect a supply voltage of, for example, 15V. I know that the output voltage and current both increase, but I don't know the math behind it. Can someone explain this to me, please? 

Question by frossiove   |  last reply


Help with LM741 op-amp? Answered

Just to test it out, I hooked up a voltage follower with a LM741 Op-amp. But, when I measure the voltages, it doesn't work. When I have problems with such simple circuits, it makes me want to kick a small animal. Please, save the small animals, help me with my circuit. When I measure Vout, I expected something somewhere around 7-8 volts, but I'm actually getting 13-14 volts. I also tried changing the resistors in the voltage divider, but the output did not change. I'm getting my power from an unregulated 12v 1A wall transformer, but I measured it at around 15v unloaded. I replaced the chip once to rule out static electricity as the problem, and I got an output 0.1 volt higher. Any ideas?

Question by WerdnaN   |  last reply


Op Amp Distorion oscillates when on high distortion?

I'm making an op amp distortion pedal, but as I turn up the gain, its starts squealing just when the crunchiness starts sounding good! Is there any way I can stop the oscillation?

Question by 8bit   |  last reply


Op amps? Which one is best?

I have a couple op amps collected over a couple years, and I am working on a design for a linear power supply, but have stability issues, and a "down to -V" common mode input voltage for op amps is a difficult parameter to find. Constraints: * Inputs must work down to as close to the negative supply rail as possible  * needs to be stable when used in a feedback loop for a linear power supply design * low noise / offset / blah blah good good goodies?? Hopefully? I'm actively testing these in a basic comparator circuit to see how far I can get the inputs to the -vee (or ground) before the op amp stops working as intended.I have tested the LM324, LM386, UA1458TC, LM741, and a few of the LT one's. Only the first 2 work well on a single supply w/ the inputs near ground or Vee LM324; // slow LM224; // ditto, but in weird thicc package LM386; // slow LM741; // ancient relics of the past, not rail to rail by any means, sucks IMO. UA1458TC // ancient relics of the past, not rail to rail by any means, sucks IMO. LM318H; // it's in a fancy metal case :D TL072CP; // JFET inputs, limited output current and the output can't go below the noninverting input. TL2072AC; // ditto. OP37; // These things aren't even that fast and can't work at unity gain. OP27; // ditto LT1007; LT1167; LT1191; LT1363; CRAZY fast, 1000V/uS!!! Maybe too fast... LT1360; LT1112;

Question by -max-   |  last reply


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741 Photovore? Answered

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Question by darkside3131   |  last reply


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Whos getting black ops for the wii?

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Topic by mrelement 


Who plays wii black ops? Answered

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Question by mrelement   |  last reply


Call of Duty Black Ops II

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Topic by Drew99-KGB   |  last reply


How to add a op amp to this circuit?

I built this circuit a while ago but the only problem i have with it is that i have to use electronics like my iPod, laptop, or anything with a high volume output. So I started reading about op amps and hwo they "jack up the signal" and I stated wondering could I somehow integrate it into my circuit so that my audio input is higher therefore allowing me to use my cellphone, tablet, and e.t.c? Currently I have a LM324 Quad amp i know fr sure i wont need all those pin. I also have a tip31 and 2N3904 transistors.

Question by tramont   |  last reply


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This is a forum for real COD players. For players who are looking for a new clan, new and just starting, and just players in general. I need the list following; A sniper A "silent person"* A man for SMG trust me this is VERY important  A person who can run well which equals marathon pro or not with lightweight I would not mind a hacker but do not totally advertise yourself on my games just on here I however rather get stuff fairly until I get angry that I lost everything when I prestige :) USA clan is not for Untied States of America, it is "Unknown Soldiers Association" HOW TO PUT COLORS IN YOUR NAME: Shift button, then number 6 which is together ^ hooray! then you put a number such as ^2 that would be green PM me or comment PM is preferred Your favorite weapon it doesn't have to be what your combat record says, your Kill Death Ratio (this will not affect anything im just wanting to know)   IT DOES NOT MATTER IF YOU ARE GOOD OR NOT I'M JUST LOOKING FOR 10 PEOPLE My ally code is 3974-2523-7244 this is my weekend account I am not able to access my everyday account on weekends sometimes I will post my daily ally code ASAP I will also try my hardest to keep you updated on ALL black ops news and call of duty. PS. Don't look stupid and say "why dont you get an Xbox or ps3?" because one i have both my ps3 is not good for connection I have no clue why, and two I dont want to pay for Xbox live. *Silent Person is to me a person with ninja pro and ghost pro, DOES NOT MATTER WHAT SECOND PERK IS Goodbye! happy shooting!

Topic by mrelement 


What is better? Black ops, battlefield or Medal of Honor? Answered

Personally, I like black Ops. I want to see what you think.

Question by DELETED_the vengeful aug   |  last reply


use an op amp to have two outputs?

Hello, I need to amplify a single mono audio input with two op amp or a single dual op amp and have two discrete outputs that can filtered at different frequencies and then those outputs have to be read with an arduino with two different analog inputs, is this possible? Thank you.

Question by dkoshkin   |  last reply




How to reduce signal noise in a circuit (for Amplifier)?

I am building a sound reactive RGB light. Using a LM386 and a 16f88's AdC. I got it to work great with just 1 RGB LED on a breadboard, powered from a 7805 I then built it on perfboard, watched the amp's output on my O-Scope, worked fine. https://randomskk.net/projects/lightstrip/schematic.pdfUsed this schematic for LM386Once I hooked up 3 Constant current regulators with 3x 3 watt LEDs(red-green-blue) through 3x MOSFETS, the Amp's output signal becomes blurry/chaotic and the light malfunctions. The regulators negative output must be connected to logic GND, which i know to be where the interference is coming from.How can I reduce the noise coming out of the Amp? Even if I gotta use different type of Amp. I don't know to much about them.

Question by PuffMag1cDrag0n   |  last reply


741 Signal amplifier Answered

How would I go about creating an amplifier using an LM741 to amplify a 0mv-400mv signal to a 0v-4v signal? All the circuits from google or textbooks don't work, or produce strange oscillations. The only way I can get it to work is in inverting mode, where I can get -4v-0v out, which isn't very useful. My specific application for this is for a digital thermometer. I intend to amplify the 0-400mv analogue signal from an LM35 linear temperature sensor, then somehow sample that without using loads of logic or transistors and convert it to decimal or binary, then drive a dual 7-segment display to show the temperature. I have a prototype made using 20 comparators and 10 xor gates, and countless diodes, so if anyone could advise me on an easier way to do that, that would be great. And no PICs/AVRs, I know how to use them and have programmers, but I prefer to do "real" electronics using CMOS chips.

Question by andy70707   |  last reply



In what electrical objects can I find op amps? Answered

Hello again, I'm searching for good op amps. They don't have to be power op amps, but it would be nice if it also had some protection circuits like a current limiter. It needs to take at least 25V differential between the negative and positive supply voltage. It should be a chip with at least two op amps inside it. Are there any broken electrical items that have these inside? I know they are 'used a lot' but somehow I don't find them often. Greetings, Electorials

Question by DELETED_Electorials   |  last reply



Whats your fave black ops gun on multiplayer

Whats your fave gun

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Question by JustinC318   |  last reply