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 The Larson Scanner on PC
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By: Anonymous: Sven () on Friday, April 06 2012 @ 02:17 PM PDT (Read 1614 times)  
Anonymous: Sven

Hello!
I've built the scanner, it worked successfully the first hours but now it seems to be dying again. (1 day later)

I am running it from the "PowerState" LED power source from the motherboard.
I have measured it to be 4Volts but I'm not sure if I'm doing it correctly.

Is 4 Volts too much?
One LED does no longer work already, the others are flickering weirdly while they fade in/out. Doesn't look like it will run much longer. When I hit the switch a few times everything goes totally corrupt and sometimes just stops or turns off.

Is the microchip broken? Are the resistors wrong?
I have no idea about this stuff, may have to buy it again. I just want to have it working for longer than 1 day.
The only problem is that shipping took 1 month to germany.Rolling Eyes

Other than that, I really loved how everything arrived and how the manual was written. I'm a total noob when it comes to electrical parts or soldering but I've managed to get it to work. lol
Great stuff!





       
   
By: Anonymous: Sven () on Friday, April 06 2012 @ 02:26 PM PDT  
Anonymous: Sven

I also have a video of the broken behavior although the framerate of the camera didn't really catch it how bad it is really looking:

http://www.youtube.com/watch?v=zS15ZTJTI7Q
(private)

and this one was taken right after it all came together and it worked all fine:

http://www.youtube.com/watch?v=BvjvbAcoATM
(private)

I don't know how to repair Oops!





       
   
By: Windell (offline) on Friday, April 06 2012 @ 03:43 PM PDT  
Windell

I am running it from the "PowerState" LED power source from the motherboard.
I have measured it to be 4Volts but I'm not sure if I'm doing it correctly.


I am not sure exactly what this power supply is giving you. It may not be a steady DC voltage-- it may be a "dimmable" PWM or constant-current LED driver. Neither of those is suitable for driving the larson scanner. If the input power is not truly DC, your multimeter will not display it, but the Larson Scanner will misbehave in the ways that you have been describing. I would suggest that you try hooking the Larson Scanner up to a DC power supply-- e.g., 3 V from the battery source --to see if there is permanent damage to the unit.

> Is 4 Volts too much?

4 V is a bit high; it will overdrive the LEDs, and can potentially damage them.


>One LED does no longer work already

This probably an unrelated soldering issue. Resolder the pins of that LED alone; it's probably OK. If that does not fix it, check the resistor with the same number, and the soldering at the chip pins as well. Poor solder joints tend to open up like this after a few days of normal thermal cycling.

the others are flickering weirdly while they fade in/out. Doesn't look like it will run much longer. When I hit the switch a few times everything goes totally corrupt and sometimes just stops or turns off.

This would seem to indicate that the power supply is not good, as I described earlier.


Is the microchip broken? Are the resistors wrong?



Try running at 3 V DC to see if the microcontroller is OK. The resistors are probably not good for 4 V operation. It would be better, of course, to use 3 V DC to drive it, and keep the original resistors.





Windell H. Oskay
drwho(at)evilmadscientist.com
http://www.evilmadscientist.com/

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By: Anonymous: Sven () on Saturday, April 07 2012 @ 07:07 AM PDT  
Anonymous: Sven

*Test, I am not a spammer*





       
   
By: Anonymous: Sven () on Saturday, April 07 2012 @ 07:13 AM PDT  
Anonymous: Sven

Whenever I try to post it says spam (I'm trying since yesterday) so I will post the image of the reply instead...

http://www.abload.de/img/postingevilmade8fyu.jpg






       
   
By: Windell (offline) on Saturday, April 07 2012 @ 12:46 PM PDT  
Windell

Sorry about that; something like 99% of the attempted posts to our site *are* spam, and it's only by good filtering that we can have a site at all. Frown

Since the "5 V" power supply was being dragged down all the way to 4 V by the Larson Scanner (which takes *very little* current), that does again suggest that the power supply was in fact intended just to drive a single LED.

I'm glad to hear that everything worked out in the end. Big Grin


Windell H. Oskay
drwho(at)evilmadscientist.com
http://www.evilmadscientist.com/

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