You can switch on an SCR.  However, the SCR will not switch off until the
voltage across it terminals drops to near zero volts.  This is good if you
are chopping a sine wave to generate an average voltage for light or motor
control.  But not good if you want to switch DC loads on/off.

Also, switching an SCR on/off with a high dv/dt will cause noise, so don't
mix SCR switching with RF receivers....



Cheers,

Paul


In a message dated 2/19/02 9:52:31 AM EST, syates@CARETECH.COM writes:

<< I know this is a basic question, but I need to ask it.

 I have always used a transistor driven by the pin of a PIC to turn on and
 off high current devices (relays, buzzers whatever).  I saw a design where
 someone was using an SCR.

 Is there any operational difference when the application is switching not
 amplifying?
 Is there a signifigant cost difference?

 What I am getting at is why would one use and SCR instead of a transistor.
 They are even in the same TO package.

 Any input appreciated.

 Shawn >>

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