18vdc convert to 12vdc

[Delboy247]

Hi there anyone here know an easy way to convert 18v dc to 12v dc found a few items on flee bay but just thought if anyone can give me any of there thoughts thanks.

 

[tazz]

Make a small votage reg, what current rating do you need?

 

[Delboy247]

Hi thanks for quick reply I won't need more than 3 minimum needed is 0.5

 

[Darkwood]

Depends on what its for its power rating etc but a dc-dc converter come in various step up or down voltages and watt ratings.

 

[tazz]

You can make a 1A regulator with 3 components, less than £1 from maplins, or you can buy them ready made

 

[Delboy247]

Tell you want I'm trying to do is run a Bluetooth adapter which needs 5v 1amp from a battery which is 18vdc 2.5ah I'm gonna hook up a ciggerate lighter plug it in a usb which I can customise just need to know how I can achieve this without melting anything looking around for a stepdown dc voltage is there anyway I can lower amperes or won't this matter as the usb steps it down further.

 

[tazz]

LM7812 regulator will give 12v stable ouput, LM7805 will give 5v stable output both rated at 1amp max,

 

[Delboy247]

That will do the job tazz how would u mount it I would need to mount it on circuit board

 

[tazz]

You can just solder together, but on a small pcb would be better heres the circuit, you can leave the caps off so therefore just solder cables to reg 3 pins + IN, COMMON NEG, and + OUT. the cap just offer smoothing if there a bit of AC present
View attachment Voltage Reg.pdf
Hope this helps

 

[Delboy247]

You can just solder together, but on a small pcb would be better heres the circuit, you can leave the caps off so therefore just solder cables to reg 3 pins + IN, COMMON NEG, and + OUT. the cap just offer smoothing if there a bit of AC present
View attachment 18239
Hope this helps

Can't see the pic mate.

 

[tazz]

click where its highlighted in blue Votage Reg.pdf and zoom in till you see image

 

[Delboy247]

click where its highlighted in blue Votage Reg.pdf and zoom in till you see image

I'm using me iPhone just logged in safari I can see the pic mate great stuff so your saying I don't really need the capacitors but advise me to do so ill pop down maplin tomorrow just gotta find the soldering gun I know I got one somewhere thanks for ur help

 

[tazz]

No problem

 

[grantr37]

That will do the job tazz how would u mount it I would need to mount it on circuit board

3mm heatshrink tube, TO220 heatsink to clip on, or a larger heatsink with a bolt, the pcb will be on ebay for about 50p somewhere....

 

[DPG]

Have I misunderstood something here. I though he needed no more than 3 amps, but minimum 0.5 ?? Might have mis-read it though. Not a problem cos obviously there's higher rated regulators around. Could the OP clarify? Daz