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Add-on Dimming Circuit

foulmist

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Hi All,

I just finished my PWM proto board (Through-Hole) for dimming the output of most types of switching regulators that feature an ENable pin.

It works with LM3410, TPS63020, and should work with other similar types of ICs. Working voltage is from 2V to 5.5V so it works right off the shell with boost drivers.

Features:
--------------------------------------------------------
PIC microcontroller
Input Voltage 2-5.5V
On/Off button (remembers last state)
Up button up-to 99% dutycycle
Down button down-to 1% dutycycle
Soft start, soft-shutdown.
Consumes less than 100microAmperes of current
Optimal NPN transistor place for inverting the PWM signal to negative.

Input Positive, Input/Output Ground are continuous with the Driver's Inputs.
PWM output + is connected to the ENable pin of the Driver's IC.

Can work with just Up and Down buttons. On/Off is not required. Every button powers the circuit at it's last state if OFF.

I can make boards at around 16mm diameter.

here is a test video with my TPS63020 driver board and a Cree-LED.
Since I don't have a laser diode to torture at the moment but expect a video soon with a working laser diode :)

PWM circuit on TPS63020 (also works on similiar switching regulators LM3410 etc. ) - YouTube
 
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sinner

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Re: Dimming Circuit

That would be the most brilliant feature that could be added to the high powered lasers,
Also A SAFETY FEATURE nonetheless, If you can power it on from the lowest current to upwards , we dont even need the keylock then...
Great job +1
 

foulmist

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Re: Dimming Circuit

That would be the most brilliant feature that could be added to the high powered lasers,
Also A SAFETY FEATURE nonetheless, If you can power it on from the lowest current to upwards , we dont even need the keylock then...
Great job +1

thanks,

I plan to integrate it in my 445nm laser, I thought of this cuz I don't constantly need the FULL output of my laser (and I presume all of you) I don't want to disassemble it just to lower the output everytime ... lol :D
 

sinner

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I would say, Take that "SmartSwitch" ..In ya Face!!! :gun:
 

sinner

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Is it possible to add a strobe mode, I know i suck on it when it comes to interpreting the circuits.. but if it is possible, That would be lengen---wait 4 it!!!! :bowdown:
 

foulmist

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Is it possible to add a strobe mode, I know i suck on it when it comes to interpreting the circuits.. but if it is possible, That would be lengen---wait 4 it!!!! :bowdown:
yep it's possible, I have to rewrite the code though, and I don't own a pic programmer, I use my dad's (which is rare) :D and the cool stuff is anyone can rewrite the PIC (anyone with knowledge :D) and completely alter the behavior of the circuit without changing any components.
 

Wolfman29

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So with a normal laser that has only a tail-clicky, how would one do this? There is only on-off. I would actually like to see an add-on circuit that can be operated with only a few mods that would add modes.
 

sinner

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You dont understand!! Guys its a whole new thing, I mean the microchip is programmable that means you can add as many modes as u want!!!
I would really like to see this one in a build.. do it do it!!
 

foulmist

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Foulmist I am assuming that you are basing this on the lm555 or similar?
no it's PIC microcontroller which means you program it with software what to do (assembler or C)

So with a normal laser that has only a tail-clicky, how would one do this? There is only on-off. I would actually like to see an add-on circuit that can be operated with only a few mods that would add modes.
well clicky is for overall power from the battery, you should add buttons to the host to operate it. I have a double action small buttons from cell phone's camera buttons. I plan to use one of these (Up/Down). When pressed lightly - UP,,, when pressed all the way - DOWN. It's pretty small so it wouldn't be a problem to drill a hole somewhere in the host and that's it :D I don't see this as something tooooo complicated ... YET :D


You dont understand!! Guys its a whole new thing, I mean the microchip is programmable that means you can add as many modes as u want!!!
I would really like to see this one in a build.. do it do it!!
yep any mode you like :beer:
I am very short on time right now, will do it first chance I have :beer:
 
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foulmist

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Here is a video as promised with a working laser diode.

My FMT drive with a LPC-826 diode attached. Current is set to 500mA. Dimming circuit maximum is 99% which is 495ma.


:beer:

I'll try to find the time to get this in a host and an SMD board soon :)
 

sinner

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Very good indeed.. Not that there is a problem but i find these specific type of smd buttons/switches to be very delicate and can wear off..

Switch suggestion: Low profile smd tact switch (possibly with gold plating)
These are used in camera buttons, Laptop computers On/Off buttons etc..
 

foulmist

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Very good indeed.. Not that there is a problem but i find these specific type of smd buttons/switches to be very delicate and can wear off..

Switch suggestion: Low profile smd tact switch (possibly with gold plating)
These are used in camera buttons, Laptop computers On/Off buttons etc..
I will let the end user choose the buttons for themselves, I will be using some low profile ones, from cell phones or laptops :) :beer:
 

Trevor

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My FMT drive with a LPC-826 diode attached. Current is set to 500mA. Dimming circuit maximum is 99% which is 495ma.
This is false. You are using PWM rather than true analog control, which means your laser is running always at 500mA.

However, it is being cycled on and off at a given duty cycle. So, your maximum duty cycle is 99% on / 1% off, and will give you what SEEMS like 99% current.

For example, 50% PWM duty looks like '''_'''_'''_'''_'''_'''_'''_'''_'''_''', rather than ---------------------. The latter would be a true 250mA analog output.

Trevor
 




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