Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Will adding a capacitor help my problem?

Joined
Sep 27, 2011
Messages
66
Points
0
I am trying to drive a 1w diode with a 14500 battery, but the voltage cannot keep up and when it drops below 3v the driver shuts off.

Here is an image of the voltage over time on an ocillascope. If I add a cap to this will the laser stay on for longer, or is it just a matter of the battery not being able to supply the current needed?

I would like to use the smallest cap possible so it fits in my build, but it seems that they come in sizes up to 5F (holy shit!) for the voltage range that I am using.

Here's the graph (sorry I forgot to post it at first)
CT4Yl.png
 
Last edited:





Blord

0
Joined
Dec 24, 2007
Messages
5,356
Points
0
What is the driver ? You can actually direct drive the M140 diode with a 3.7Volt cell. A member did that without problem. I forgot his name. The laser won't be regulating of course.
 
Joined
Sep 27, 2011
Messages
66
Points
0
That's a neat build for sure, but I am trying to make something really little. I tried adding a 100μF cap to my 14500 - but the result was identical. I have a 1Farad cap at school I can try out tomorrow and see if there is any improvment with that. It looks like an IMR 14500 just cant keep 3volts when under that load.
 
Joined
Feb 23, 2012
Messages
1,282
Points
0
Adding a capacitor won't solve the problem.

Seems like the cell isn't supplying enough current. Either the driver's undervoltage protection is kicking in or it's the cell's PCB.

Having a charged 5F cap as an additional power supply may keep the voltage up for a few seconds, but it still will drop rapidly.

Is this a boost driver?
 
Joined
Sep 27, 2011
Messages
66
Points
0
Adding a capacitor won't solve the problem.

Seems like the cell isn't supplying enough current. Either the driver's undervoltage protection is kicking in or it's the cell's PCB.

Having a charged 5F cap as an additional power supply may keep the voltage up for a few seconds, but it still will drop rapidly.

Is this a boost driver?

It is not a boost driver. It is a very minimalist driver (I did not make it myself) - it has a 3 to 5 volt range, so I can't use 2 lithium cells

It's not the cell that is stopping the laser because I am using an IMR cell that can really supply like crazy for how small it is (not to mention that they are not protected). Even when the laser starts to flicker the cells are not yet warm to the touch. I run 10Watt XMLs off of these same cells with no problem (and they do get warm), so I am pretty baffled that they can't support my 1W laser. I guess the LED drivers I use have boost regulators...

What if I were to use an LED driver with my laser before my laser's driver? It wouldn't be so efficient, but the LED driver could keep the voltage up for the Laser's driver... It sounds crazy, but could it work?
 
Joined
Feb 23, 2012
Messages
1,282
Points
0
If you're not using a boost driver, the only thing the driver's going to do is drop the voltage even further. So, it's better not to use one at all IMHO.
 




Top