How to convert 12v dc to 24v ?

Is there easy way to convert 12v to 24v.Found some circuit diagrams to increase voltage but dont know they are working.

I brought a snail horn for my motorbike but it's sound very low. i know my motorbike battery is the reason for this, I need to increase voltage to make my motorbike horn louder.

i'm currently testing 555 timer voltage doubler circuit on 123d circuits.  You can simulate it here  555 timer voltage doubler

Give me a straight answer for this.. 

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Question: Is the horn rated for 12V or for 24V?
If it is for 12V than doubling the voltage is a big NO-NO!
If it is for 24V it will impossible for your little battery to supply the current required.
Keep in mind that if the horn only needs 8amp to sound properly you will need to supply at least 16 amp from your 12V battery to the buck converter - and it is hard to find a buck converter for these power levels.
Usually electric horns have a little adjustment screw that controls the vibrations of the metal disk inside - mark the position and try if you get a better sound by adjustng it, if not set back to the mark.

ishan udyoga (author)  Downunder35m1 year ago

Thnks for the help.. horn is supported for 12v and 24v. my motorbike battery is 12v 5A . i did adjust that screw but didnt worked. any ideas...

Ok, let me rethink this one...
Usually they are either for 12 or 24V not both unless they come with the corresponding electronics or seperate connections.
So yours should then have 3 terminals: Ground, 12V, 24V - if not I would simply assume it is 24V only.
Connect it to a good sized car battery, if in doubt directly with some thick wires - if there is no sound you won't make it work on your bike either.
If it does work on the car but not on your bike you can still substitude for the missing amps:
Get a supercapcitor as used for car audio equippment - the big cans with huge terminals and a display for the voltage.
Connect parallel to the battery and use the output from the capacitor with a switch for the horn.
It mow should be able to get over 20amps for a short time burst - enough to make a lot of noise.

ishan udyoga (author)  Downunder35m1 year ago

ok.I'll try it. thnkyou..

iceng1 year ago

Just drew this up for you using an isolation 12v control 400cps transformer.

Really any isolation control xfmr will work but less efficiency. If you use 40Amp mosfets you wont need as much heatsink.

POWER 12--24VDC.bmp
ishan udyoga (author)  iceng1 year ago

hey.. thnks for this diagram .. how many amps gives in output, my horn needs 48 watts.so 5x12=60 .I dont think my battery gives me exactly 60w it drops 15w or 10w power . is this diagram work for this...

Happy to hear your horn will work.

Current_I = Power / Volts = 48w / 24v = 2 amps or just 4 amps to run your horn on 12 volts...

iceng iceng1 year ago

And now you only need a 2A transformer, I assume intermittent horn use.

ishan udyoga (author)  iceng1 year ago

ok. thnks for the help sir...

Increasing voltage with a doubler won't help if you can't increase current too. You really need a proper boost switching regulator

ishan udyoga (author)  steveastrouk1 year ago

is there any diagrams for this. Thanks...