matt, I'm sorry but you get out in proportion to what you put in.

We have had many non experts come to AAC and receive first class help to design, build or fix difficult circuits; from horticulturalists who wish to control their greenhouses to radio model enthusiasts to guitarists to cyclists to..........the list goes on and on.

But this can only happen with their cooperation.

Do you consider your post #19 a suitable answer to WBahn's very clear post#18 and reason for him or anyone else to bother further?

 

Scott,
I appreciate the links to the info on OpAmps, but the question he was asking is a bit more than just reading a DS for data. I believe he is trying to ask if he can use an opamp to create a voltage follower or analog output. I may be wrong, but those Datasheets probably wont help solve his question very well and may confuse him even further. Studiot was onto the answer in his reply I think.

Bob

Thanks.
The Op has confused and changing his questions, and I just trying to figure out what he want, what I linked wasn't the normally datasheet of OP amps, they are the application collections of Op Amps, there are many applications circuits inside, I just thought maybe he can refer to them, and he can thinking more and describes want he really want.

 

Im sorry for not being of more help but that is the limit of my knowledge. I also thought I had answered the question. What more information can I provide so that you can help.

In relation to your statement

"you get out in proportion to what you put in."

Are you saying if inputing 5v into an op amp you can only get out 5v?

Perhaps the solution is being lost on people fixated on the op amp. I just want to have an output of 2.5v to 0v controlled by a thermistor within temp range of 30-60 deg celcuis respectively. I really don't know what else to say. I have came hear because I need help and unable to design a suitable circuit. Im not interested in dealing with people who keep saying you cant do this or that. I would really like to hear from someone who says "Hey mat perhaps you could try this......." If the op amp wont work make a suggestion that will or for the betterment of this thread keep your comments to your self.

 

Wanting to measure temperature between 30 - 60 degrees. The output needs to be between 2.5 down to 0 v as it gets hotter. I got to the voltage dividing circuit to linearlise the output and no further. Options seem to be using transistors, a chip or op amp. As long as it works I'm not fussed on what's in the circuit.

Okay, this is a start. One thing that is missing is that there is no way for me to tell if this is 30°F to 60°F or if it is 30°C to 60°C.

You keep saying, elsewhere, that you are using a thermistor, but don't give any indication here that this is a requirement or even a desire -- in fact you say that you aren't fussy. So which is it?

What is the environment in which the temperature measurement will be made? It is in air, in liquid, of a solid surface?

What kind of accuracy do you need?

How fast do you need the voltage to change in response to a change in temperature? Is it okay if the voltage changes fairly slowly, say over 30 seconds, if the probe were to be moved quicky from one end of the range to the other?

 

Perhaps the solution is being lost on people fixated on the op amp. I just want to have an output of 2.5v to 0v controlled by a thermistor within temp range of 30-60 deg celcuis respectively.

Okay, so now I know it's °C. Good.

I really don't know what else to say. I have came hear because I need help and unable to design a suitable circuit. Im not interested in dealing with people who keep saying you cant do this or that.

We can't provide effective help until we understand what you are trying to do. We understand that you lack the background to know what it is we need to know. You need to understand that we are operating in a vacuum at arm's length and don't know enough about what you are doing to know what we need to know, either. Trying to measure the slowly changing temperature of piece of steel is very different from measuring the rapid change in temperature in a heat duct. The questions that need to be answered are different.

So we need you to work with us because only YOU can provide the information needed -- what WE can do is try to help you identify what that information IS.

I would really like to hear from someone who says "Hey mat perhaps you could try this......."

Okay. Hey, Mat, perhaps you could try a remote IR thermometer and feed the digital output to a programmable power supply and program it to output the voltage you want for a given temperature.

Under some circumstances, this might well be the optimal solution for you. Probably not. But if you want to shortcut the process, that's the kind of "help" you are likely to get -- people forming an opinion of what you NEED based on the little bit of data presented and then making recommendations that are complete mismatches to your actual needs but which you have little or no basis to realize are just blind rabbit holes.

[/QUOTE] If the op amp wont work make a suggestion that will or for the betterment of this thread keep your comments to your self.[/QUOTE]

You don't get to dictate terms. You came asking for help from people that are choosing to donate valuable time to you without asking anything in return. Every minute I spend working on your problem is a minute I could have been helping some other poster with their problem, getting paid $2 for from a paying customer, getting ready for the start of the semester that begins in two more days, playing with my daughter, sleeping, or just watching a movie. I've chosen to help you -- you can choose to cop an attitude if you like, but just keep in mind that I can change my choice at any time. The same is true with everyone else here, in more or less the same ways.

 

I appreciate and value constructive input.

The circuit will be sampling air temp. Ntc Thermistor I believe is probably the most robust, cost effective, and versatile option for generating the temperature input. The one I purchased had a response time of about 15 seconds from one extreme to. So within the operating temperatures response time will be acceptable.

 

Hello,

We warned you about the quest to find a solution for your automotive need.
We already closed the other two threads you have started:
Pwm controlled b thermistor
and
Pwm controlled by thermistor

Looking at this thread, you are heading the same way, trying to avoid the automotive need.
The last time we said that a ban would be given.
A ban of 7 days will be issued.

Bertus

 

Hello,

I got this in a report from WBahn:

I wasn't aware that you had posted this question previously related to a topic that is against AAC policy, and then posted it again trying to disguise it, and then posted yet again trying to disguise it further. Whether you or I agree with the policy is not relevant, the fact that the owners of the forum have the perogative to set their bounds for the forum is.

But more than that, you have taken the approach of asking people for assistance while intentionally trying to deceive them. Do YOU like being deceived by someone asking YOU for free help?

I have no desire to interact with people that demonstrate your level of integrity (or lack thereof) and will therefore not help you further with ANY question you ask. Choices have consequences.

Bertus