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How to make a 5 V 1A adapter with 741 op amp?

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sr13579

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I am stuck with this project here. I was trying to make a voltage controlled current source which can generate 1A with 5V. I used a digaram of 741. But it didn't work. Is there anyone who can help me with showing me a circuit that can work? Thanks.
 

dknguyen

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In the future, provide a schematic of what you actually used or else we just end up guessing how you actually went about things.

The 741 doesn't have enough current capability so you need to provide larger current capability through a transistor buffer at the output.
 

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sr13579

Member
In the future, provide a schematic of what you actually used or else we just end up guessing how you actually went about things.

The 741 doesn't have enough current capability so you need to provide larger current capability through a transistor buffer at the output.
I would like to provide one. But the circuit is very common. That is why I didn't add. Thanks very much.
 

crutschow

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What is your supply voltage?
 

AnalogKid

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That is like telling a mechanic that your car does noqt work, but nothing about symptoms, make, model, ect. A schematic isnt everything, its pretty much the only thing.

ak
 

Grossel

Well-Known Member
dknguyen has already provided a shematic. The only aditional to fill in is voltage source and pin numbers, and you're good to go.
And of course the resistor values.
 

audioguru

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The design of a 741 opamp is 50 (!) years old and it was designed to use ONLY a plus and minus (total of 30V) supply.
Its useable input voltage range is limited and its output voltage swing is also not much. It has the same low maximum output current of most opamps.

A newer opamp can use a single supply voltage that is much lower and would work much better.
 

crutschow

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Most Helpful Member
Note that the 741 will only work to within about 2V of the negative rail, so if you have a single positive supply voltage, the minimum input voltage will be 2V.
A single-supply op amp, such as an LM324, or any rail-rail op amp will go down to zero volts on the input.
 

AnalogKid

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dknguyen has already provided a shematic. The only aditional to fill in is voltage source and pin numbers, and you're good to go.
And of course the resistor values.
And - figure out which of the two schematics is the one you want.

ak
 
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schmitt trigger

Well-Known Member
I would like to provide one. But the circuit is very common. That is why I didn't add. Thanks very much.
This is a very condescending and pedantic answer to the people who are attempting to help you.

We know that there are hundreds of circuits on the web. I would easily bet that 2/3 of them have fatal flaws. Additionally, you may have substituted components, or changed values, or exceeded ratings. Audioguru's comment that a 741 won't work with a 5 volt supply is a prime example of the latter.

Without a schematic and even actual images of what you built, how can you reasonably expect to obtain help?
 
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