1.5A 445nm buck driver with reverse battery protection

[imraneesa]

I was asked by one of my friend to make buck driver with reverse battery protection. so i modified the same buck driver which i had posted earlier and when i gave it to him he was happy.

1. Full set of c8 flash light parts with my buck driver.

2. This is the driver 1.5A

3. Back side of the driver

4. Driver fitted inside the c8 driver holder. The holder was modified to suit the driver size.

Thats it. will come back again. Thank you for watching guys. This driver worked very good.

 

[gozert]

Thanks for posting. Would you mind explaining us how you did it?

 

[imraneesa]

Yes of course.

Regarding the driver i used mosfet to protect the driver from the reverse polarity. all the parts soldered on the board is by using torch which was difficult but i made it. i dont have soldering station. i will quickly buy one once i get some income. and regarding the host adjustments this is what i did.

I made my driver little bigger to accommodate all the parts without congestion. Then i opened the C8 flashlight and took the driver holder and measured the outer diameter and also the outer diameter of my driver board. then i took the holder and fit it into the lath machine and turned it until my driver fitted good into the holder. and i created little grove so that i can easily remove the board from the holder.

Thats it again. have a wonderful day. will be back soon.

 

[Benm]

So how does this reverse polarity protection actually work?

There are plenty of solutions in electronics for this, but i found making in mechanicallty imopossible to insert batteries the wrong way far more elegant.

 

[Cyparagon]

So how does this reverse polarity protection actually work?

A few varieties:

Of course, not just any FET will do. They need to have appropriately selected Vgs values - logic level perhaps. Operation with a single lithium cell might not work. I'm not sure on availability on FETs that are fully "on" at Vgs of 3V.

i found making in mechanicallty imopossible to insert batteries the wrong way far more elegant.

That'd be nice! Of course, this is exceedingly difficult to do, given the symmetry of 18650s

 

[imraneesa]

I used pchannel mosfet. yes physically making it impossible to fit is difficult in the case of lithium round cylindrical batteries unlike 9v battery. even though 9v batteries have different type of connectors for +ve and -ve while inserting we still make a mistake by touching them wrong side. and if there is no switch in between the sensitive components you are blowing it. so best practice is to use reverse protection with some diode or mosfet as explained by Cyparagon.

And yes mine worked very good. i have inserted wrong side and nothing happened. driver is safe and so is the diode. happy happy ending.