Op Amp Pin Connections for Temperature Control Circuit: V+ and V- Wiring Clarification

Hi, in my temperature control circuit i was ask to connect pin of my op amp to batteries V+ and pin 7 to V-, but it did not work , and it damages the op amp, please what can i do to rectify the fault ?  

Ephraim..your instructions said"Connect your 9V battery + side to the V- of the 741 opamp (pin 4) and the - side to the V+ to pin 7".Does this not ring alarm bells?  Connecting + to - and - to +?  I'm afraid you have probably destroyed a couple of 741s here...good thing they are cheap!  You don't want to do this sort of thing with an expensive ADC chip!When you have any doubts (and the above instructions should have raised huge doubts) refer to the data sheet.  Just google (IC number) datasheet - in this case "741 datasheet" and you should easily get what you need.Here's one:http://www.ti.com/lit/ds/symlink/lm741.pdf
on the first page is a diagram showing supply V+ and V- but no pin numbers.  Scroll down to page 3 and there is a pinout diagram and a table confirming that V+ goes to pin 7 and V- goes to pin 4.So I have three pieces of advice for you:1. If you get contradictory instructions like the above, CHECK them.2. Learn to find (and read) DATASHEETS.  They are the references against which you can check facts if you're in doubt.  Our expert Elizabeth Simon is currently writing a series on reading datasheets, they probably go a bit deeper than you need at this stage but there is lots of very good information in these articles.3. Don't worry about blowing up stuff sometimes.  It happens to the best of us.  I nearly did it with a PICAXE controller chip I got a couple of years ago.  Just LEARN from the experience.Finally, go back to whoever wrote those instructions and...well maybe not punch them on the nose, but point out they are WRONG!

I would have to say that the problems you are being asked to solve , and this is not the first one, seem to be badly prepared. If you check a data sheet for a 741 op amp  you will  find that the V+ pin is  7, and  V-  pin 4, your questioner has transposed them.If you reverse the power supplies, normally the device will fail, and there is no option but to replace it.Cheers,Richard

David offers a good suggestion, which is to read Elizabeth Simon's "How to Read Data Sheets" series of articles. This column provides links to most of them:The Hidden Horrors Lurking in Data Sheets
And here's a link to one she wrote after the above column:How to Read Data Sheets: Logic ICs
At some stage, Elizabeth is going to cover data sheets for op-amps -- I'm going to ask her if she wants to mention this forum thread as part of that column.

As David says -- we all make mistakes -- the trick is to learn from them. If I had been in your place, before doing anything I would have checked the data sheet and compared it to the instructions. It's not that I'm really clever -- just that I've been caught out by things like this so many times before. A simple "rule of thumb" is to not trust anything anyone tells you until you've confirmed it from another source (the data sheet, in this case).

Hi guys!Datasheets are indeed very important, and I rarely go through a product without having one.However, a real challenge would be - what if there is no datasheet? For example, a rare product may have been phased out and the datasheet has been dropped by the manufacturer from their website.If this step of misfortune happens, the first best course of action is to look at the datasheet of other products within its family. For example, a series may have similar codes from a manufacturer and the pin-outs may most probably be similar (just differing in package).Since we're not entirely sure, another precautionary note would be to set the current limits of our supplies to a relatively low level (lower than the rated operating characteristics in the co-product's datasheet). Doing this lessens the chance of IC damage/destruction.In the unluckiest case that the product has no family, we can set the supplies to the lowest current limit possible and check between pins for a diode connection (to see if there are any pins that are pulled up to the other). By doing this you'll know the GND or supply pin of the IC. (that'll be 2 pins down - boo yeah!). To know which one is GND and which one is supply, just follow the diode test (naturally the anode will be GND and the cathode will be supply - an ESD diode which is naturally reverse-biased).
Hehe.. hope this helps too in anyone's future debugging sessions.Best regards,Justin