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Need help...12v to 14v dc converter

Thread starter #1
I want to build a 12v to 14v converter with LM2577T-Adj but i found 12v to 16v scheme diagram, any one can help what part i should chance to...?
in this scheme to make 12v to 14v output...?
 

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#2
It's going to be more than one... Check the datasheet, it's relatively straight forward, just follow the formulas and don't skimp on the inductor.
http://www.electro-tech-online.com/custompdfs/2008/05/LM1577.pdf


If you wanted to be EXTREMELY el-cheapo, you can add 3 silicon diodes to the output to drop it by approximately 2.1V This however will vary with the current being drawn and isn't recommended. If you don't care about proper regulation, then this is okay, otherwise do it properly....
 

ericgibbs

Well-Known Member
Most Helpful Member
#3
I want to build a 12v to 14v converter with LM2577T-Adj but i found 12v to 16v scheme diagram, any one can help what part i should chance to...?
in this scheme to make 12v to 14v output...?

hi,
Reduce R1 [12k] to about 10.5K.
This is the Vsamp feedback to the switcher.

Look at the Vout formula [near the Vout terminal]

Vout = 1.23 * [1 + 10.5/1] = 1.23 * 11.5 = 14.14Vout.........OK?
 
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#4
Have you checked that the appliance designed to run from 14V won't run off 12V?

The chances are you're wasting your time as you don't need a switching regulator.
 
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Thread starter #5
hi,
Reduce R1 [12k] to about 10.5K.
This is the Vsamp feedback to the switcher.

Look at the Vout formula [near the Vout terminal]

Vout = 1.23 * [1 + 10.5/1] = 1.23 * 11.5 = 14.14Vout.........OK?

thanks to remind me about the Vout formula....but i don't find the 10.5 resistor so use 22k and 2k and the result in the tester 14.3....
thanks to every body for the help........... :D
 
#6
Have you checked that the appliance designed to run from 14V won't run off 12V?

The chances are you're wasting your time as you don't need a switching regulator.
How would you step-up from 12V to 14V without some kind of switching power supply? ;-)
S.
 
#8
How would you step-up from 12V to 14V without some kind of switching power supply? ;-)
S.
The chances are the device will work from 12V so a 14V supply is not required so building one would be a total waste of time.
 
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#9
The chances are the device will work from 12V so a 14V supply is not required...
Hero may be right here. But if you still want to do this, go to National's website and run their WebBench software. You can design and simulate your circuit before building it. It will assist with all the parts values.
 
#11
Hey there! need some help. I have a 12V/2.3AH RESERVE-battery and I have a 12V battery in my vehicle. Can I charge me 12V/2.3AH RESERVE-battery with my cars battery using this circuit i.e. stepping up the DC voltage and then charging me RESERVE battery. Will it be OK?
 

tcmtech

Banned
Most Helpful Member
#12
I would just connect it to your vehicles electrical system and start the engine.

It will automatically charge your battery being the alternator puts out around 14.4 VDC when the engine is running.

No reason to over complicate the simple.
 
#13
The best way is to use a 12v relay , connect a live from the switched side of the fuse box to one of the trigger contacts & the other to the thin wire leaving the alternator , that trips the warning light on the dash . When the alteranto begins to charge the wire goes to ground & completes the circuit energising the relay .

You then simply use a suitable guage fo wire from the vehicle battery to the relay WITH A FUSE IN LINE ! & continue from the relay to your second battery .

If you want to be really lazy car accessorie shops & caravan/camping stores sell split chrge relay kits that are pre wired .

Use of he relay stops your secondary battery supplying power when starting the vehicle

hope it helps

Oh 35+ years working on cars / trucks / boats Etc.
 

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