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 What Type of Switch?
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By: Anonymous: folsompoint () on Tuesday, June 07 2011 @ 05:53 PM PDT (Read 3354 times)  
Anonymous: folsompoint

So what type of switch is used to change the speed, and brightness? an spdt, spst, dpdt, dpst. I just want to be able to mount the switch off the board in a project box.






       
   
By: dnewman (offline) on Tuesday, June 07 2011 @ 07:34 PM PDT  
dnewman

Quote by: folsompoint

So what type of switch is used to change the speed, and brightness? an spdt, spst, dpdt, dpst. I just want to be able to mount the switch off the board in a project box.



It's a tactile switch. Aka a push-to-make switch. The particular switch on the EMSL Larson Scanner only has two leads, is normally open (NO), and is only closed when you hold the button down. Release the button, and contact is broken and the switch is again open.

The only panel mount tactile switches I spotted at Digikey are lit (LED). Mouser likely has some too, but their parametric search didn't allow "panel mount" as one of the selection criteria. You may find more choices by looking for a spring-loaded, panel mount toggle or rocker switch. Various types are made which will only close the switch while you hold the toggle or rocker down: once you release it, the spring pushes the toggle or rocker back, opening the switch.

Dan


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By: dnewman (offline) on Tuesday, June 07 2011 @ 07:59 PM PDT  
dnewman

Better yet, look for SPST momentary switches. You want one where the switch function is "off - momentary" or "off - (on)" and the circuit function is SPST-NO (Normally Open). Should find plenty of those at Digikey, Mouser, or your local parts store.

Dan


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By: folsompoint (offline) on Wednesday, June 08 2011 @ 06:33 PM PDT  
folsompoint

so if i got a toggle switch from Radioshack that is normally off, that should work?


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By: dnewman (offline) on Wednesday, June 08 2011 @ 07:31 PM PDT  
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Why not a push button switch from Radio Shack such as part 275-1566, 275-1556, 275-644 or 275-618? All of those are panel mount, momentary switches. The difficulty with a toggle switch is that, unless it is a momentary switch, it will then require that you toggle it twice: once to initiate the speed change and then again to get it back to the normal "state" of not being "on". My read of the Larson scanner code suggests that as long as you have the toggle switch flipped to "on" (closed), the speed change won't occur. It's not until you flip it back to "off" (open) that the speed change is then effected. This is as I would expect given that the code expects a momentary switch to be used.

Dan


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By: squall_line (offline) on Thursday, June 09 2011 @ 06:24 AM PDT  
squall_line

Quote by: dnewman

My read of the Larson scanner code suggests that as long as you have the toggle switch flipped to "on" (closed), the speed change won't occur. It's not until you flip it back to "off" (open) that the speed change is then effected. This is as I would expect given that the code expects a momentary switch to be used.

Dan



Even more than that, an "extended" press on the button is how one changes the brightness. So a toggle switch, if used, would be extremely prone to brightness changes rather than speed changes.

It's even that much more betterer to use a momentary switch in this case.


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