Help with 741 op amp...

[Cybios]

Well I have a circuit that takes sound input. It runs it through a 741 op amp and then turns on bit on or off if there was a high sound. I don't have the values of the resistors and whatnot figured out and hoped you guys could check my work and maybe route me to some pages on how to calculate the values. Or hey if your really bored you can do it for me!

 

Edit forgot the link hehe...

http://img.photobucket.com/albums/v358/lookatmytool/Schematic2.png

[YT2095]

any clipped input you`ll get through D1 and past R2 will go directly to ground as a dead short!

C1 and R1 will get no signal at all and therefore neither will pin 3

[Cybios]

http://img.photobucket.com/albums/v358/lookatmytool/schematic3.png

I think I fixed it, I moved the ground to the other side, Should it even be there at all?

 

If you can tell me how to get the values of the resistors somehow.

 

Also I am making a remote transmitter please tell me if this would work...

http://img.photobucket.com/albums/v358/lookatmytool/remote.png

 

Each button is numbered at the top when that button is pushed the output of the second 555 is supposed to 'beep' that many times.

[YT2095]

no again, now you will get a signal past C1 and R1, but are taking the non inverting input to deck (ground). it will have the same effect as your prior wrong circuit`

 

as for R values, it all depends on what you wish to acheive (that wasn`t made exactly clear either).

as for R3 and R4 they should be at the same value though, as a 741 and/or 301 equiv like to have a bias of 50%

so two 10 k resistors for those would be just fine

[Cybios]

I was thinking the op amp would turn on the output at a high sound. Would like 2.4 volts be good for this?

 

So what your saying I need to take the grounded out completaly?

[YT2095]

no, not at all but you`ll need TWO diodes back to back, that way you`ll have your clipping effect, you`ll feed pin 3 between the junction of these 2.

thereby giving a min .7v threshold and no more to pass per input.

 

I`m kind of thinking you want a Volume sensitive ON/OFF switch device here?

[5614]

whilst this isnt being useful i dont think this thread is being either really.

 

you really need to learn how to wire in a 741 op amp switch... whilst YT and I could, it wouldnt help you learn, you need to look at a working diagram (from a text book or something) and actually understand how it works, read up about, once you understand it and how each pin works its very easy to use.

[Cybios]

Yah I am trying to make a volume switching device.

 

I have looked at many diagrams and read up on how it is used but just I couldn't really find anything close to what I am trying to make.

 

Maybe give me a tutorial on what I need to know?

[YT2095]

for a start never clip the front end!

 

pre-amp it 1`st then clip and filter, after that you`ll need to amp again, re-clip and gate it.

 

after the gating, you can more or less switch what you like

[Kedas]

start reading a few things here:

http://www.technologystudent.com/elec1/opamp1.htm

even more basic lessons:

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/OpAmps/OpAmp1.html

 

In case you don't know an opamp is an amplifier not a magic toy.

[YT2095]

In case you don't know an opamp is an amplifier not a magic toy.

 

although in principal I agree with you, they can be made to function in very versatile ways.

a 741/301 can be made to do alot more than a transistor for instance (that`s only an amplifier too!).

 

cut the guy some slack

[Cybios]

Ok well this is what I have for the transmitter and the reciever. If anyone was wondering the reciever is plugging in to my parallel port so the output of the reciever is supposed to be one spike, 2 spikes 3 spikes, etc.. all the way up to six as on my remote.

 

My remote

My reciever

[Cybios]

Well YT, what do you mean by clipping it and filtering it? I don't know if I did it right but on sme other boards they said it would work. I looked at those tutorials Kedas and really didn't find out anything I already knew.

[Kedas]

I looked at those tutorials Kedas and really didn't find out anything I already knew.

 

Then read it again until you learned something.

Because there is no way that someone who understands what's on those pages is making an OpAmp based schematic like yours.

 

maybe this will help you:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opampvar.html

 

notice that all examples with exception of the comparator have a feedback line (out-signal changing in-signal)

[Cybios]

Well its not really the 741 I am having problems with. I know how to use it I just can't figure out how to make it so it will work with the sound input. I also am trying to make a comparator so thats why I don't have a feedback line.

[Kedas]

So you just want to know if signal reaches a certain amplitude.

then you can use that second 741 schematic

 

so your problem is located in the basic resistor, capacitor knowledge, do you want a few links ?

 

first think of it what will happen if there wouldn't a capacitor in your circuit.(DC)

this means that the output will flip any time that insound is high enough

(in-0.7)*R1/(R1+R2)>5v*R3/(R3+R4)

your power supply isn't symetric so some limitations there.

 

to understand what happens with the capacitors look up some data about low-pass filters. (you don't want to detect spikes in your insound)

 

about your other schematic switching the power supply (VCC) of an IC is never a good idea.

[Cybios]

Ok, it'd be cool if you post some links. Then do you know of any other way to get one pulse, two pulses, three pulses ect... out of a circuit when you push a button?

[nettron]

Also I am making a remote transmitter please tell me if this would work...

 

No, the 555 (U2 ) circuit wont work as depicted in the schematic, the push-buttons ( 1 thru 6 ) should be connected to ground instead of +9Volts, check it out.

 

Also the trigger input ( pin 2 on U2 ) likes to see a nice high to low pulse transition, pressing SWT9 will momentarily float this pin giving possibly unpredictable results , instead try connecting SWT9 (use a N.O. PB) to ground and put a resistor ( about 10K ) between pin 2 and +V. Do the same thing for the reset ( pin 4 ) but connect the resistor to ground and use a SP pussh-button instead .

[Cybios]

Well is this better?

 

[Cybios]

Oha nd also in the reciever is anyone positive that is I have a radio plugged into it if the rectifier will work, because I happen to have found a small transformer that I bought and never used.

[reverse]

although in principal I agree with you' date=' they can be made to function in very versatile ways.

a 741/301 can be made to do a lot more than a transistor for instance (that’s only an amplifier too!).

 

cut the guy some slack [/quote']

 

 

Support from me.

 

Maybe he isn't into reading,

Good on him for getting hands on experience.

[nettron]

Well is this better?

 

Better yes but still not what was suggested , disconnect pin 2 from pin 4 and re-read other post. Also do a google search for 555 monostable .

[Cybios]

Yah actuallt I'm thinking of screwing this whole thing on the remote and just use a microcontroller. I also need to know if anyone knows of a site where it has a schematic for a radio where you can pre-tune it to 1mghz AM somehow?