[simpits-tech] controling a 28v circuit with a 5v

[Gene Buckle]

>  But this exposes my lack of electronic knowledge so my question is,
>  what would be the simplest way to toggle a 28v DC circuit with a 5v 
> 20mA DC circuit?

Use a transistor.  If you didn't know already, a transistor is nothing 
more than a fancy electronic switch.  What you can do is use the 5v to 
"bias" the transistor, turning the switch "on".  The transistor has three 
legs to it.  They're called base, emitter and collector.

Connect the base to your 5v source, the 28v source gets connected to the 
collector and you connect your lamp to the emitter.

You want to use an NPN transistor for this as the transistor turns "on" 
when the base is pulled "high" relative to the emitter.  (PNP would 
require exactly the opposite, which you could use, but you'd have to have 
an inverter inserted between your +5v from the Simkits output and the PNP 
transistor)

You want to use a transistor with a TO-220 package style - these are 
commonly used for the exact purpose you're going to use them for.  This is 
what they look like: 
http://commons.wikimedia.org/wiki/Image:TO-220_Front_Coloured.svg

You'll want to find one that can handle the 28V input voltage as well as 
the load in amps you expect to place on it.

g.



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Proud owner of F-15C 80-0007
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