I don't see how the circuit in post #37 can provide a few mA for an indefinite period of time as the OP desires.

It CAN NOT provide a held voltage for much longer than enough time for a meter to make an accurate reading. Several milliseconds at best. Totally not what the TS is requesting, which the TS has not answered the questions asking what the purpose and application would be. So I suggest waiting until the TS responds with a description of the application, instead of simply repeating the request.

 

See, friends, I want a circuit to use that works like the hold switch in a multimeter and can sample the dc voltage source instantaneously, but as a momentary push button, this storage is until we press the button again and the new value is stored.

The HOLD button on my multimeter is a momentary button. Push it once, it holds the last value it sampled. Push it again it goes to sampling again. A third time and it holds again.

How does that not meet your needs?

 

Greetings to friends and teachers.

First of all, thank you for your cooperation and kindness in answering my question.

See, friends, I want a circuit to use that works like the hold switch in a multimeter and can sample the dc voltage source instantaneously, but as a momentary push button, this storage is until we press the button again and the new value is stored. I already mentioned that the voltage is from 0 volts to 24 volts dc.

Thank you for giving me your experience and time.

You said the same thing three times before.
You are doing it again for the 4th time.
Each time you have added NO NEW INFORMATION.

What is your point in repeating yourself?
We are now over 40 replies into this thread and we are no closer in being able to provide you with an appropriate solution.

Write down the reading measured on your DMM.
Is that a workable solution for you?

 

I think the solution has already been offered in the ADC-DAC digital approach, but that might be a little too abstract for the OP.

Perhaps a block diagram can be offered...and let the OP work out the details.

 

Unwatched

 

Once again the TS has stated the request without one word about any application.
Given that the TS has simply re-stated what they asked for in similar terms, which implies to me that none of the responses have been understood, or possibly not even read.
Could this be an AI powered troll?? Now I ask the TS to respond and let us know what part of the world they are in, so that we can have a clue as to what sort of resources they might have available.

hello
My friend, I am not very good at English and I ask and answer my question with google translator, so I apologize if I caused you any doubt.
while in my country the internet is very slow and filtered (Iran)

Dear friends and respected professors.
I already said that I want a circuit that can read and store the voltage value on the DC line by pressing a button.

 

I already said that I want a circuit that can read and store the voltage value on the DC line by pressing a button.

What are you going to do with the stored value?
Send it to your customer in another country via mail?

 

I am looking for a practical circuit where I can give it a momentary dc voltage as a sample by pressing a switch, and this sampler circuit can hold it in itself so that I can use that voltage if needed.

I know I said I was unpatching this thread but:

What are you going to do with the stored value?

Use that voltage? How? For what purpose?

FOR WHAT ? ? ? How is this stored voltage to be used? How much POWER do you want this stored voltage be capable of supplying? HOW LONG do you want this stored power to be useful?

This is why I'm dropping out of this conversation; it's going in circles. And yes, Google Translate is probably the reason why these questions are going unanswered.

 

hello

The sampling value is now read-only and remains constant until it is read again by pressing the key and new values are recorded.




Suppose we have a power supply, we want to know and measure the voltage exactly by pressing a key at any moment. It is exactly the same as in digital multimeters with the hold key, but in analog form.

 

با مقدار ذخیره شده چه می خواهید بکنید؟
آن را از طریق پست برای مشتری خود در کشور دیگری ارسال کنید؟

See, I have a module with IC ICL7017 which is a voltage display. In new ICs of this series, such as icl7117, it has a base called hold, which can save the value at the moment.
Now how can I design a circuit for this measurement of this module.

 

For the 6th time, you are still saying the same thing.

Watch the display and write down the value.
Or use your camera on your phone and take a picture of the display.

 

I think the solution has already been offered in the ADC-DAC digital approach, but that might be a little too abstract for the OP.

Perhaps a block diagram can be offered...and let the OP work out the details.

In new ICs of this series, such as icl7117, it has a base called hold

So use the one that has the hold feature.

If you are trying to modify the one without the hold feature, that may or may not be possible.

Trying to sample the voltage and then reproduce it is a silly solution that will cost you more in time effort and money than just getting the newer chip.

 

I think the solution has already been offered in the ADC-DAC digital approach, but that might be a little too abstract for the OP.

Perhaps a block diagram can be offered...and let the OP work out the details.

If the TS ever responds with questions about the system I described, I will provide all of the details that I can recall. I did this back in the early 1970's era, so it is not fresh in my memory.
I wonder if we are being "Trolled" by ........