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Re: DC Protection


 :
12/29/2000 3:30 PM
Rob Strand
Re: DC Protection
This one's a pretty standard circuit:  
 
 
 
http://www.geocities.com/ResearchTriangle/8231/tra/index.html  
 
 
 
It provides DC protection and also a dethumps the speakers during power-on.  
 
 
 
If you don't have 12V floating around here's a few mods:  
 
 
 
-Remove R8/D4 (not necessary)  
 
 
 
- Break the connection between R3/T1-Collector and D3/Re1  
 
 
 
- Connector a 5W resistor in series with the relay. The value is chosen so you get 12V across the relay when the relay is on. If your supply voltage is low you might get away with a 1W resistor.  
 
 
 
- Connect a 12V zener from R3/T1-C to ground and a resistor from this point to R8/D3/Re1. The value  
 
of the resistor is chosen based on your supply voltage so that about 3 to 5mA flows through the resistor.  
 
 
 
- Connect your +V DC rail to where the existing +12V goes.  
 
 
 
Regards  
 
Rob
 

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