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

Topic by juggalo_assassin183   |  last reply


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

Topic by Catt123456   |  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!

Topic by XxsonicxX   |  last reply


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


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


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

Hey- trying to make led's light up to music, and i need to know if a tda2822 amp will light up ~15 leds (maybe more). i will be splitting them into high-mids- and lows. highs 3 leds, mids 4, and lows 8 leds. Sorry this question is so sketchy but i am writing this quickly. Power supply and necessary parts are not a problem. Thanks :)

Question by astroboy907   |  last reply


help with lm386 OP amp?

I'm running my guitar's output signal into an Lm386 op amp to light up some LED's, but the amp puts out a constant signal instead of just when I play. What can I do?

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


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


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


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


is it possible to determine the direction a motor is spining by attaching a comparator to both leads?

The motor is not being powered with electricity it is being spun by hand. and if it is possible how can I determine the speed.

Question by evilmadscientistman   |  last reply


Can I remove Vista as an operating system and install XP?

The title says it all, I just want to know if I can remove windows vista from a computer and install windows XP home onto it.

Question by Tombini   |  last reply


741 Photovore? Answered

Does anyone know of a photovore made with some Cds Cells (light dependent Resistors) and a 741 Op-Amp? I have been looking for one, but have been unable to find them. A photovore is a small robot that goes towards the britest spots ( look up Lm386 Herbie)

Question by Michael_Bell   |  last reply


i have a konami arcade cabinet i got at target with built in games, anyone know hot to add games or another card in it.

Its the konami with 11 built in games, i found taito superman game and i want to use the cabinet i have instead of building one ...im not too smart.? i have a budget of about 200 bucks and thats about how much it would cost for the superman card, building the cabinet would add about another 100-200. any ideas??

Question by darkside3131   |  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


Can I use a MC1741CP op-amp instead CA3130 op-amp

I am doing a school science project, and I need to build I device. I do not have a CA3130 op-amp but I need one. Can I use an MC1741CP instead?

Question by sierra.williamson   |  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


CONSOLE GAMING COIN OP ARCADE MACHINE

Can some one tell me the parts i need to buy to make my ps2,wii and xbox 360 a timed arcade coin op machine and/or an instruction manual please,please help,any info would be great,ive been interested in it for years and searching internet for ages,i ask the company where i can get parts like a timer board but they NEVER helped me yet,otherwise i wouldnt be asking here,please help anybody,so i can begin the project soon

Question by JustinC318   |  last reply


Question about op amp frequency response? Answered

Hello , i have some question about op amp frequency response. i use non inverting like the scematic below.If i set  R1=10kΩ  , C1=220nF  ,  R2=100Ω  , C2=1uF . R1 and C1 will set low frequency response of opamp at 72Hz . R2 and C2 will set high frequency response of opamp at 1592Hz.  But how much it affect the signal in dB ? and how its affect the signal if i set R2=100k ,C2=1n (gain~11)? Can you give me the formula please ? Thanks very much! Sorry for my bad English!

Question by login721   |  last reply




VACUUM TUBE OP-AMP USING LOW VOLTAGE TUBES?

I would like to build a low voltage op-amp circuit for an analog computer. Can it be done ? I would like to use tubes in the 12 volt range. The idea is to construct an analog computer like the Heathkit EC-1, but using low voltage tubes for the op-amps. The EC-1 is very expensive, and hard to find on Ebay etc. Any ideas? Thanking you in advance, Wayne Verish

Question by gort59.5   |  last reply


Is there any way to make a touch sensitive switch using an OP Amp? Answered

I just saw an i'ble about making a touch sensitive switch. The problem was that it used 3 transistors, and I wondered if there was any way to make one using only an OP Amp. Thanks.

Question by arhodes18   |  last reply


will my acer aspire 5251 laptop computer run call of duty black ops.?

I antcall of duty black ops but i have a wii version that is bad to many glitches i want the pc verson but someone suggest this check your pc to see if this will work so will it run on my computer.

Question by werewolfhunter   |  last reply


Converting sounds into motion without a microcontroller

I want to build a circuit which converts 3 specific frequencies into a voltage, then to be used by 3 different servos, I don't need to use a microcontroller!! what should I use other than microphone, op amp, 555 timer, servo and comparator for this circuit?  Which one is better LM567 OR LM2907 to convert the frequencies? Thank you in advance!! Waiting for your reply ASAP :) Joe,)

Question by joee1   |  last reply


Operational Amplifier not working? Answered

Hello, I'm trying to use the KA324 IC (which consists of four opamps) for amplifying an audio signal. I've tried almost every schematic from this website: http://sound.westhost.com/dwopa.htm and also from lots of other websites, but none of them work. If the output volume is Really low, the sound is pretty good, but very quiet. When I turn up the volume, the sound is really bad, I almost can't recognise the song I'm playing. The output volume is also not that really high. If I keep increasing the input voltage, the output stops increasing after a while. It's not really 'loud' at that moment too. I've connected the IC to 12V DC (between the two middle pins). The + input goes to the ground connection, the - input goes to my POT voltage divider of the input voltage. The output pin goes straight to the speaker. I also added a 100kOhm resistor between output and - input. Without that resistor, I hear nothing at all but I think that's normal. I've also tried the three other op-amps from that IC but no luck. Is this opamp just not ment for audio amplification? or am I doing something wrong? Greetings, Electorials

Question by DELETED_Electorials   |  last reply


Can I use 741 op amps instead of 1 LM324 in a heart rate sensor?

Http://makezine.com/video/visualize-your-heartbeat-with-this-homemade-pulse-sensor/

Question by DangerousTim   |  last reply


Voltage follower for the INA125?

I need to use a voltage follower that runs off a 9 v battery (actually, two batteries so +- 9V is available), from the output of a Burr-Brown INA125 amplifier to the analog input of a DATAQ data acquisition unit. The DATAQ is running at about 1000 data points per second.  Is there a particular op-amp that would be useful in such an application?  Or would something besides an op amp be more useful?  Thanks!

Question by Prfesser   |  last reply


Need help with caculate non inverting op amp gain? Answered

Hello .I need help with caculate gain of this non-inverting opamp .Can you tell me how to caculate the gain of it when the pot at 100% please ! Thanks ! Sorry for my bad English!

Question by login721   |  last reply


wondering, if i replace the hard drive in my system do i need a new mother board?

Tried to reinstall my op system in my old dell dimension 4300 (my kid chewed it up and spit it out!!) but find that my hard drive is shot and needs to be replaced...if i do this will i need to replace the mother board as well?? is there anything else i need to keep in mind when i do this, i am new to doing repairs like this....by the way any tips or hints on uninstalling and re-installing system ops would be greatly appreciated, just to make sure i'm doing it right!! LOL thanx much...

Question by hunnynspice   |  last reply


I got cod black ops for the wii and it doesent want to connect to the internet help?

I wanted to play online but it wont connect to the internet i can get on facebook on the wii but the game wont connect ho do i fix it?

Question by Don,t try this at home   |  last reply


Modify this circuit to make it lower voltage? Answered

What resistors do I change in this circuit to make it go red at <3.2V and green at >3.2V ? It is a battery monitor that uses op-amp, 2.5v voltage reference diode, and a 2-pin bi-color LED. The trimpot adjusts the voltage at which the colour changes. http://i48.tinypic.com/28qtb3l.gif

Question by jdorne   |  last reply



Nerf Dragonfire Drone

I have been thinking about a design for a nerf variation of the dragonfire drones from black ops 2. It would consist of two remote control helecopters of relatively large size, and some kind of firing mechanism mounted in between them. Any suggestions or input? I need ideas!

Topic by nerfrocketeer   |  last reply


Active mixer and 180 degrees out of phase question? Answered

Hello , i want to make a simple active mixer to place in front of the power amp. I read some documents about active op-amp mixer.And they said : "Any signal entering the inverting input of the op-amp will appear at the output but it will be 180 degrees out of phase.If the output of the first op-amp were recombined with one of the other signals at a later stage it would cancel out rather than mix. So we have to re-invert the phase with yet another op-amp." and the schematic should like figure 1 to re-invert the signal . But if i use the the mixer to direct feed input of power amp , can i use the schematic like figure 2(w/o re-invert the signal) ??? Thanks in advance! Sorry for my bad English!

Question by login721   |  last reply


Is there a difference between a high pass filter with an op amp and a high pass filter without one? Answered

I'm trying to modify a guitar effects pedal of mine to remove some squeaking and decided that a highpass/low pass combo with some potentiometers to modify the highpass and low pass points (since my pedal emits squeaking at different frequencies on different settings) and I was wondering if I should use a high/low pass with an op amp, capacitors, and resistors - or just a simple resistor and capacitor filter. Does anyone know if either configuration is a detriment to sound quality?

Question by Squag   |  last reply


Can't get a TLC272IP OP-AMP to work. what am I doing wrong? Answered

Hello I received this week a few TLC272IP op-amp and I wanted to test them. I created a circuit on a breadboard which looks like the attached image From what I read on the net, this is a  typical non inverting amplifier schema where gain should be (1 + R2/R1) I connected PIN 3 of the TLC272 to pin 3 of my arduino uno and using PWM I set the output to roughly 1V ("analogWrite(3, 51);") I used my voltmeter to read the voltage between ground and pin 3 and I could really see 1V  given I used R1 = R2 = 47k, I was expecting to have a gain of x2 and thus read voltage of 2V between pin 1 of the op-amp and ground  I get something that is very unstable, below 1V. I tried with 4 different TLC272IP I just got and get the same behavior. am I doing something wrong there? what do I miss? or do I need to review how op-amp are really working? (I purchased the TLC272IP because it's supposedly single power supply) thanks for any hint. JM PS. in some doc i read that I should not let the second op-amp in the air, so i tried as well by connecting pin 5 to ground and shorting 6 and 7 with a wire or a small 100k resistor but this did not change anything.

Question by jm-l   |  last reply


Will this processor be able to handle good games?

I'm looking at an AMD Athlon II X4 645 Quad Core Processor and I just wanted to know if this will be able to play games like Portal 2, or Black Ops without lagging.

Question by Ke-Bob   |  last reply


How to increase NE555 output amplitude?

Hi, I have the following circuit: http://s17.postimg.org/86bus6rm7/Sawtoot_Gen.png which is able to generate a nice sawtooth waveform. When I provide 13.12 volt as power supply, the max peak of the sawtooth will be near to 8.7 volt. There is a viable way to increase this value at least to the same value of the power supply (13.12 volt)? And can someone provide me a schematic based on my circuit? I suspect that this would be viable using a transistor or an op amp on the output, am I right? If i had to implement  an op amp, I prefer to use a "single power supply" op amp, and a common IC (eg an LM358?) Kind regards.

Question by akopelumenuscu   |  last reply