I have kind of brought this topic up before, but now I’m getting a little more serious about it. So I want to add a potentiometer for smooth increase and decrease of brightness. I ordered a 5a potentiometer which is yet to come. Ill be using a single mode 1.5a buck driver as a power source. Some of the thing I read say I need a resistor in there somewhere, but no quite sure. Anyone got knowledge or experience with this? Help and suggestions are much appreciated!
Any spec’s for the potentiometer?
Resistance is variable with pot’s, you have resistors on the driver and if I’m correct you can adjust those to vary the output current. So if a pot is connected to the board in place of the fixed resistor it can be used to adjust the current to the led emitter.
But you could also change the resistance on the driver like it’s normally done to give a high curent output from the driver and then put the potentiometer in series with the led emitter so when it’s adjusted it’ll vary the brightness of the led. But this will be much more inefficient, am I correct in thinking that the first method above would be best as the size of the pot can be much smaller, I don’t know what size as I haven’t modded these drivers yet
A stop on the pot or a fixed resistor could be used so the resistance has a minimum setting, if it went too low the current would increase to a level too high damaging the driver/led.
I’ve probably got it all wrong, I may not be back to check.
http://m.ebay.com/itm/281068418887
Here’s a link to the potentiometer I purchased.
You can either replace the since resistor with the POTS or put it in parallel either will change the brightness depending on POTS position
Sorry to spoil your day, but that is a high-ohmic potentiometer 250000 Ohm. It is only the on/off switch that can handle 5 Amp. Hardly usable for your project.
Do you have any suggestions of what will work?
forget the potentiometer and go with a ramping driver. waaay easier.
Definitely an easier way to do it.
A pot would work but it’s going to be difficult until you learn about them, where would you fit the adjustment for the pot. It’s all possible, just a small hole, reach in with a hex key etc or a small shaft to turn. I’m not sure if anyone wants to explain with step by step instructions.
+1
There are mechanical solutions such as Magnetic control rings and Quantum tunneling (foam material) but that is NOT easy to implement as a DIY job.
My only problem with a ramping driver is all the flashing though modes. I want to using this for hunting, and all the flashing may spook game away. I want a smooth transition from low to high. I know it can be done. Here are couple of examples:
How about a dive light with stepless dimming?
It’s doable with a potentiometer but not to use the potentiometer to control the input current :
You can use the potentiometer + another resistor in series to create a voltage divider, and then user Attiny to read the voltage from the middle point. The voltage will vary with potentiometer and so the ATtiny can figure out which PWM to put out.
^this.
Putting a pot in series with the LED just wastes power in the form of heat.
in my opinion those are what i call gimmick lights. alot of bells and whistles you just dont need. i build ALOT of predator hunting lights. 99% of multi mode and ramping circuit lights get returned in exchange for one mode high only. most hunters cannot adjust the brightness, run a e-caller, focus on the target all while a predator is running in, at night. just too much going on. simple is better in this situation. scan with as dim a light as possible and when critter is in range , flick the gun light on and squeeze the trigger.
it its a T20 or T50 much easier to just back off the focus a little if you need less bright.
There’s a very very easy solution to that.
I hear ya there. I personally like 3 mode lights myself. At 1.4a, I find myself scanning on med and only using high when trying to light up a body. I guess I just had something to prove. It’s only an experiment to see if I could do it. Probably turn into such a pain, wouldnt want to do it again.