Forum Index > Projects > Larson Scanner kit and LED Menorah kit support
 Momentary Switch/USB
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By: Anonymous: madsolder () on Sunday, December 07 2008 @ 08:07 PM PST (Read 5778 times)  
Anonymous: madsolder

I have two of these fabulous kits in my possession that I am trying to get done prior to Hanukkah. I want my kits to be powered off USB. I figure this should be possible because the chip runs on 2.3-5.5 volts. I may just throw a resistor in to help bring it down closer 4.5 though.

The big problem is that I don't want to have to unplug the USB every time I want to cycle the lights. I picked up a tiny momentary switch, but it is normally open which is just the opposite of what I need.
Can the reset pin be used in someway to cycle the program?
Maybe I need a circuit like this one
http://www.kpsec.freeuk.com/trancirc.htm#inverter

I think I am going to resort to unplugging the USB. It is only once a day I guess. Just hoping someone would throw and idea at me that I hadn't thought of. Thanks all.





       
   
By: Windell (offline) on Sunday, December 07 2008 @ 08:45 PM PST  
Windell

You can use USB to power the circuit, but I'd suggest adding a resistor between the 5V from the computer and the chip-- maybe 50-200 ohms or so. To use your switch, hook it between pin 1 and ground (or pin 10).


Windell H. Oskay
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By: Anonymous: madsolder () on Monday, December 15 2008 @ 07:08 PM PST  
Anonymous: madsolder

Finished it a couple nights ago. Is there a place to post photos of individual projects made with this kit? The switch works great. I added a 100 ohm resistor at you suggestion. I am really happy with it and getting ready to send it off to my friend. One final question.

The LED connected to pin 10 and 11 (ground) appears to be dimmer then the others. This is especially noticeable when it and the center are the only ones on. Is this normal?





       
   
By: Windell (offline) on Monday, December 15 2008 @ 07:14 PM PST  
Windell

You can post projects in the Evil Mad Science Auxiliary; see the link on the right hand column of this page. The pin on the end is sometimes a bit dimmer-- but the difference is normally pretty minor. I wonder if it's made worse by using the USB power-- it might look better with a higher-value resistor.


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http://www.evilmadscientist.com/

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