erdabyz
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NOTE: if you don't wanna read technical details, go to the end of this post.
As some of you may know, i've said some times at this forum that i was going to make anithing like electronic switches or similar... and then i ended doing nothing. But this time it'll be different. I had a nice idea, how about having an addon for your laser driver which would allow you to change your laser's power SAFELY on the fly? This can be done, just changing the driver's original potentiometer for a digital potentiometer.
Well, some of you may say: that is very complicated, just add a external bigger potentiometer and you could adjust the output twisting it, without more electronics...
Well, true, but laser drivers's current reponse is not directly proportional to the pot's resistance, and as you turn the pot, smaller resistance changes means bigger current changes.
So, having a potentiometer with a mechanical way to make it stop turning at a desired point is not a good idea. Multi turning potentiometers would be a solution, but the mechanical part would be difficult to make, and it should be adjusted for every laser.
How about electronic potentimeters?
First, we need 100ohm potentiometers for a daedal driver, and i have to test the value of a rkcstr driver's pot. (or lavadrives too)
There are NO commercially available 100 ohm digital potentiometers... and there are NO low resistance potentiometers with enough taps (steps).
The best i've found is a 1024 taps, 10Kohm potentiometer...
So, ¿how can we make a 100 ohms potentiometer out of 10k ones? Well, just putting two of them in parallel and making calculations, i can get a range of resistances from 30 to 100 ohms, with 0.5 ohms resolution (each step increases 0.5 ohms the resistance), and if neccesary, i can also get 0.1-0.2 ohms resolution.
But this calculations require a microcontroller to store the wiper's position of the two potentiometers and set it. Also the potentiometer has a serial interface.
The microcontroller will also allow calibration for every laser's max current to avoid going over that value and frying the poor diode. And will also allow a threshold calibration, so your diode will lase in the whole range.
Two push buttons will be the interface, one to increase power, the other to decrease, and some combinations to enter calibration mode.
The addon will be smaller than a rkcstr driver, and will work from 2.5v to 5.5v.
I'll have to make them by hand, expect quality, but not a lot. I won't be able to make ig amounts of them unless it sells very good. the firmware of the microcontroller won't be open source because it's gonna be a HARD program and i don't want it copied.
What i've done until now is:
-programming a part of the software
-Requesting some samples of the potentiometer
-thought about some issues and how to solve them
And now, the most important part, it'll be a bit... expensive.
Digital potentiometers are $5 a piece (expensive hardware... but required)
Microcontrollers (PIC12F683) are $1.10
I'll make them by hand, so the final price will be about $10 plus shipping.
I'll also sell only preprogrammed microcontrollers for $2+shipping.
I will post more details of the project if you want. But i have a... bad english and some times i can't express as i want.
So, FOR THOSE THAT DON'T WANT TO READ THE ENTIRE POST,
WOULD YOU PAY $10+Shipping FOR A SAFE WAY TO CHANGE YOUR LASER POINTER' S OUTPUT POWER ON THE FLY?
As some of you may know, i've said some times at this forum that i was going to make anithing like electronic switches or similar... and then i ended doing nothing. But this time it'll be different. I had a nice idea, how about having an addon for your laser driver which would allow you to change your laser's power SAFELY on the fly? This can be done, just changing the driver's original potentiometer for a digital potentiometer.
Well, some of you may say: that is very complicated, just add a external bigger potentiometer and you could adjust the output twisting it, without more electronics...
Well, true, but laser drivers's current reponse is not directly proportional to the pot's resistance, and as you turn the pot, smaller resistance changes means bigger current changes.
So, having a potentiometer with a mechanical way to make it stop turning at a desired point is not a good idea. Multi turning potentiometers would be a solution, but the mechanical part would be difficult to make, and it should be adjusted for every laser.
How about electronic potentimeters?
First, we need 100ohm potentiometers for a daedal driver, and i have to test the value of a rkcstr driver's pot. (or lavadrives too)
There are NO commercially available 100 ohm digital potentiometers... and there are NO low resistance potentiometers with enough taps (steps).
The best i've found is a 1024 taps, 10Kohm potentiometer...
So, ¿how can we make a 100 ohms potentiometer out of 10k ones? Well, just putting two of them in parallel and making calculations, i can get a range of resistances from 30 to 100 ohms, with 0.5 ohms resolution (each step increases 0.5 ohms the resistance), and if neccesary, i can also get 0.1-0.2 ohms resolution.
But this calculations require a microcontroller to store the wiper's position of the two potentiometers and set it. Also the potentiometer has a serial interface.
The microcontroller will also allow calibration for every laser's max current to avoid going over that value and frying the poor diode. And will also allow a threshold calibration, so your diode will lase in the whole range.
Two push buttons will be the interface, one to increase power, the other to decrease, and some combinations to enter calibration mode.
The addon will be smaller than a rkcstr driver, and will work from 2.5v to 5.5v.
I'll have to make them by hand, expect quality, but not a lot. I won't be able to make ig amounts of them unless it sells very good. the firmware of the microcontroller won't be open source because it's gonna be a HARD program and i don't want it copied.
What i've done until now is:
-programming a part of the software
-Requesting some samples of the potentiometer
-thought about some issues and how to solve them
And now, the most important part, it'll be a bit... expensive.
Digital potentiometers are $5 a piece (expensive hardware... but required)
Microcontrollers (PIC12F683) are $1.10
I'll make them by hand, so the final price will be about $10 plus shipping.
I'll also sell only preprogrammed microcontrollers for $2+shipping.
I will post more details of the project if you want. But i have a... bad english and some times i can't express as i want.
So, FOR THOSE THAT DON'T WANT TO READ THE ENTIRE POST,
WOULD YOU PAY $10+Shipping FOR A SAFE WAY TO CHANGE YOUR LASER POINTER' S OUTPUT POWER ON THE FLY?