Salvaged components

I have a TL071cp which according to the data sheets is an opamp, which I also remember reading about when reading about the lm317 I think.

And a TC1427 which according to the data sheets is a 1.2A high speed MOSFET driver used for powering mosfets, switch mode power supply or small motor controls. While studying mosfets voltage regulators I remember reading something about smps. Could I use this as a voltage regulator or current regulator?

I already ordered a few components but have not yet received them:

LM317 - voltage regulator
AMC7135 - current regulator
pc817 - someday i plan to work with an optocoupler
tl082 - opamp
4n35 - opamp

So I could use the tl071cp to amplify the sound of a heartbeat for example :slight_smile:

I saw this in the data sheet:
Screenshot 2016-06-22 16.07.00.png
but the chip looks like this:
opamp.png

So should I use the diagram on the left or the one on the right?

TL071 and TL072 are different parts. Use the correct pinout for the part you have. The datasheet has the diagrams and a list of pins for each part and package.

These particular opamps are not usable for 5V single-rail operation, they are spec'd for +/-5V minimum supply range (ie 10V single rail). A low voltage rail-to-rail opamp is more useful.

Oh duh! I didn't notice the 01/02 above the parts.

As for the 10v vs 5v(low V ramp to ramp) opamp...if I wanted to use this I would need to get 2 Arduino to power 2 rails with 5v? Which would be silly?

Or I could get a separate power source like a battery pack and a voltage regulator?

Any good entry level tutorials for op-amps?

I only have this tutorial which is fine, but I don't understand if its or how to relate it to single rail vs multirail:

https://www.youtube.com/watch?v=TQB1VlLBgJE

Ok so the spec sheets say:

  1. LM324 = 3-16VDC +/-?
  2. LM1875= 16-60VDC +/-
  3. LM741 = 12-22VDC +/-
  4. TL071cp = 15-18VDC +/-

I’m not sure I’m reading the spec sheets right? Only the 324 is a low input voltage opamp?

LM324 - that's a quad op-amp (4 in 1 pkg), and it's designed for single-ended supply (+V and Gnd).

'tutorials', the Forrest Mims booklets present decent examples.

https://books.google.com/books?id=-sE7JVywygQC&pg=PA23&lpg=PA23&dq=Mims+op-amps&source=bl&ots=pl2Ktf2Qv7&sig=kFwzxcGZ1qL8e8e6aGmMQxUxmy0&hl=en&sa=X&ved=0ahUKEwiDnqq7kMLNAhUlS2MKHY30COMQ6AEIRDAG#v=onepage&q=Mims%20op-amps&f=false

4n35 - opamp

A 4N35 is an opto-coupler, not an op-amp. (Just a typo?)

I'm posting because I want to make sure I can get an opamp I can use. I form have a desktop power supply (yet). But I have 9v batteries I could use for a +/- 9V supply opamp.

So basically from those 4 models of opamps (yes 4n35 was a mistake) the lm324 is the only one I can use. I just wanted to make sure I was understanding the spec sheets correctly because I hadn't noticed before and I ended up buying a tl071/tl082 which I won't be able to use.

Back in the day all opamp circuits were +/-18V (or +/-15 or +/-12). Every device had at least a 36V supply rating as a result. No-one even thought of rail-to-rail! That was the 70's, nearly half a century ago, progress has been made since then!

If you want to see what the top performing modern opamps are like, look at something like the AD8656, 0.25mV offset, ultra low noise, true rail-to-rail input and output, 1pA typical input bias current, 2.7 to 5.5V supply, no phase-reversal.

“I have 9v batteries I could use for a +/- 9V supply opamp.”
Noteworthy.

vs.

“So basically from those 4 models of opamps… the lm324 is the only one I can use.”
Only if you insist that you can only use an op-amp specifically designed for “single-ended” supply.
But not necessarily.
What do you mean by “use”, anyway?

“I ended up buying a tl071/tl082 which I won’t be able to use.”
Only if you insist that you can only use a “single-ended” supply. But not necessarily.
What do you mean by “use”, anyway?

Do you really want to do anything or do you just want to complain?

Complain? I didn't realize it sounded like I was complaining. I just ordered the low voltage lm324 to use with the 2 9V batteries but that will take a while. In the meantime I was trying to see if I could use a tl071 that I found in an old device. But I learned that it's specd for 15-18V so I guess I can't use it unless I get 4 9V batteries.

I want to do a tutorial I saw on YouTube where they amplify the sound from a small mic to listen to a heartbeat.

@Marciokoko I do like your enthusiasm. Some call it being 'full of p*ss and vinegar'. ;)

Marciokoko: I learned that it's specd for 15-18V so I guess I can't use it unless I get 4 9V batteries.

http://www.ti.com/lit/ds/symlink/tl071.pdf Figs. 3 and 12, for instance, inform me that's not absolutely so.

The supply range depends on the output required. If you were to attempt a x100 amplifier with a +/- 9V supply and a 0.5V signal in, then that won't "work". Maybe you should give that two 9V battery option a go. I don't know what your ability to salvage is. I don't know whether the parts are good

There's a summing amplifier circuit and an audio amplifier project in the link that I provided in Reply#10. He cites a 741, but the TL071 ought to rough it good enough. The basic comparator circuit on pg 27 ought to work, too. I'd put the transistor's emitter to Gnd and the LED in series with R4 there. I think that most of the 741 circuits ought to work with the TL071.

Ok there seems to have been a couple of misunderstandings...

  1. Im not complaining. If anything I tread lightly in these forums. I'm quite thankful for all the help I've gotten.

  2. From what little I understand about opamps, they have a supply voltage parameter that specifies the range required to operate it otherwise the output will be "clipped" Or affected in some way. I only have batteries to work with until I can buy a power supply. Since connecting too many batteries in series would be cumbersome, two 9 volts is what I'm aiming at. I take it that would not work for running the op amps with high voltage ranges (>9V). That is why I said only the LM324 would work with my "two-9V battery power supply" option, right?

Marciokoko: That is why I said only the LM324 would work with my "two-9V battery power supply" option, right?

No, not right.

If an output anywhere near 18V is needed that's one matter. The LM324 doesn't "need" 18V. Ideally, outputs don't get clipped till signal voltage X gain > supply voltage.

http://www.neatcircuits.com/op_amp.htm

Ok but I can’t take an opamp like lm741 or TL071 or 82 and use them with a couple of 9V batteries, or can I?

It is possible - in my opinion, distinctly so. How is it impossible? (That's rhetorical.)

I dont know! I was asking. I am just learning about opamps. I guess I misunderstood that I needed a large voltage supply to "feed" one of these things, since the datasheets say they have input voltages of 12 and 15 and 30VDC.

So basically the input voltages only matter if the output you want is quite large, in which case you want the input range to be wide enough to accomodate the output? IOW, if I want a 12V signal, I need an opamp with a +/-15VDC so that its wide enough to accomodate a 12V output signal? So that means that if I just want a 5V signal, Im fine with a range between +/-9V?

Marciokoko: I dont know! I was asking. I am just learning about opamps. I guess I misunderstood that I needed a large voltage supply to "feed" one of these things, since the datasheets say they have input voltages of 12 and 15 and 30VDC.

Although it is great for focusing on many topics, a forum is not an effective place to get a general education. Op amp data sheets have all the information you are asking about, and many of them also include dozens of example application circuits. In addition, there are numerous online resources that delve into op amp circuits in great detail. I'm not trying to drive you away, it's just that you will get more learning benefit from exploring those fundamental resources, trying to understand the examples, and if possible, prototyping them so you can see how they work in reality. I'm not preaching down to you. It's exactly what I did to learn about them.

For example, the question you asked in reply #17 is answered very clearly in any datasheet for the devices you mentioned.

Hi, If you were to get the full lecture on OpAmp theory, they would teach you about OpAmps with a double ended supply, a +, - and gnd.

Such as back in the good old days LM741, you had +15Vdc, gnd and -15Vdc.

As technology advanced and digital appeared and single ended supplies became popular. So OpAmps are now designed if possible with single ended capabiltiy with virtual gnd at 1/2 Vcc.

Most early OpAmps could not conduct their outputs within less than about a volt of the supply rail, modern circuit techniques have solved that and some OpAmps can conduct up to very close to their Vcc. Also most early OpAMPs did not perform well with low supply voltages, now technology has improved.

So when checking OpAmp parameters, these things have to be taken into consideration.

Tom... :)