24v to 12v

[moonstreat]

24v to 5v

Hi! someone can tell me a circuit that makes me go from 24v to 5v?

 

[Reloadron]

Title says 24 to 12 and post says 24 to 5 so which would you like? Generally you would use a simple voltage regulator circuit like a 7812 or 7805 but you don't mention any current requirements?

Ron

 

[sanalece]

Use 7805 Voltage regulator IC

By changing the Resistance R you can vary the output from 5 V to 24 V.

if you don't want to Vary the Out put Then shot the Center Pin to the Ground.

1 Amp is the maximum for this IC

 

[ericgibbs]

View attachment 38716


Use 7805 Voltage regulator IC

By changing the Resistance R you can vary the output from 5 V to 24 V.

if you don't want to Vary the Out put Then shot the Center Pin to the Ground.

1 Amp is the maximum for this IC

hi,
I would suggest that you check the circuit drawing you have posted.

 

[sanalece]

Here is a small correction in the above Circuit



Thank You Eric , I didnot Notice it....

10 Uf capacitors are not mandatory, it is a good practice to put , it will avoide spikes....

 

[crutschow]

As with any linear regulator, make sure you heatsink the regulator to dissipate the heat generated from the regulator voltage drop: (Vin - Vout) x current.

 

[MikeMl]

Sanalece,

That is a particularly poor way to jack up the output of an LM7805. The current that flows out of the GND pin is a stong function of temperature, the input voltage, the phase of the moon, etc.

The better way is to use a LM317 with a voltage divider (two resistors) to set the output voltage. If you have to use 7805, then the voltage divider upper resistor must be like 100Ω so that the current out of the GND pin is a small fraction of the total current that flows down the divider...

 

[sanalece]

Sanalece,

That is a particularly poor way to jack up the output of an LM7805. The current that flows out of the GND pin is a stong function of temperature, the input voltage, the phase of the moon, etc.

The better way is to use a LM317 with a voltage divider (two resistors) to set the output voltage. If you have to use 7805, then the voltage divider upper resistor must be like 100Ω so that the current out of the GND pin is a small fraction of the total current that flows down the divider...

But let me ask you one thing, What is the current requirement Here ?

I mentioned the circuit is for 1 Amp maximum usage, it is enough for that, Much complicated then we can have much functionality....! Let the Needer replys We will C then........!

 

[mneary]

But let me ask you one thing, What is the current requirement Here ?

I mentioned the circuit is for 1 Amp maximum usage, it is enough for that, Much complicated then we can have much functionality....! Let the Needer replys We will C then........!

The circuit is bad no matter what the current requirement. The OP hasn't responded to the question regarding current, nor to the ambiguous voltage.

You should not ever simply put a pot in series with the common lead of a 7805. It will regulate poorly if at all, and may be unstable. The performance will vary widely from lot to lot and amongst manufacturers.

As MikeMl said, the best approach is to use a properly designed circuit using an adjustable regulator. My preference is to use a fixed regulator for the voltage that's intended.

 

[sanalece]

I used to it, I made it and it is working very well, all the regulator has its own ranges at least .1 V variation if you spend Dollars on that... But this circuit cost Rs 10/- Only up to 1 Amp it will work well, with 24 V input, Test it , try for a 10 Ohm resistor 1 W or 1/2 W, The Heat it produces....etc etc If the Amp is less the Heat it produces will be less, Don't You Understand mneary


More over the resistor is connected to ground, it will not produce much random voltages or noise to it.......!

 

[mneary]

7805 quiescent current can vary by 8% with load changes and 13% with input voltage changes. A single resistor in series with the common line of a 7805 may be stable if the input never changes and the load is constant.

A properly designed circuit will always work.

 

[sanalece]

Your Theory I am accepting, you can get all the details with the 7805 with it data sheet, and Work on it Please - You will understand this

 

[mneary]

I've been using the 7805 for a long time. A very long time. We appear to differ on the definition of what a good and proper regulator should do.

 

[sanalece]

I've been using the 7805 for a long time. A very long time. We appear to differ on the definition of what a good and proper regulator should do.

Hi, Friend - Who is here speaking about a regulator Char....s... I know what a regulator - But Understand one thing that, what the author of this post says, let us wait for him.....


Take it easy my Friend

 

[MrAl]

Hi there,


I have to agree that putting a resistor in series with the GND terminal of a 7805 or similar regulator is not a good idea unless you can tolerate a wider than usual regulation range. In particular, i would think a 100k resistor would have to be very very bad. There are a number of reasons why this isnt a good idea.
Yes, it "works", but what else it does is makes the regulation worse than with just a plain 7805 with no resistor, and it can be very much worse as the other posts alluded to. I guess if this isnt a problem because the application can tolerate the larger voltage swing then that's fine, but i myself dont like cutting corners in this way. I would rather use an LM317 too.

There's only one application i can think of that benefits from a resistor in the ground lead, and that is when you want to make sure that one regulator is slightly higher than the other by a very small amount, and in that case the resistor is made quite small like 10 ohms. A small resistor boosts the voltage by a small percentage and so the regulation stays almost the same as a bare 7805.

 

[dougy83]

Hi, Friend - Who is here speaking about a regulator Char....s... I know what a regulator - But Understand one thing that, what the author of this post says, let us wait for him.....

The author told me that it's crap.

 

[sanalece]

Wait - when i found time i will attach a multimeter and i will show you the video of the same..

What auther it is , he does not mention the power requirement of the regulator, i am waiting for him......!

Even i don't know why he send such a simple thing...

Do he need a power supply with good accuracy then specify its characteristic bosssesss .......!

 

[Hero999]

How much current does it need to supply?

Sorry if you've already said, I quickly read the tread and could've missed it.

The LM7805 is only good up to about 1A, beyond that you can use a booster transistor or get a higher current regulator but it's often more advisable to use a switching regulator because it doesn't waste so much power.

 

[mneary]

OP logged off ten minutes after posting the question and has not returned. All we know is he probably has 24V and might want 12V or maybe 5V at some unknown current, if any. We have been answering each other with the usual result.

 

[Reloadron]

OP logged off ten minutes after posting the question and has not returned. All we know is he probably has 24V and might want 12V or maybe 5V at some unknown current, if any. We have been answering each other with the usual result.

My take is pretty simple. The OP returned to the thread and suffered a massive information overload and his head exploded before he could post. Additionally I would not rule out the possibility of alien abduction.

Ron