5 t0 12 volts problem

• 5 t0 12 volts problem
  Posted by J4e8a16n on 12 Feb, 2014 14:39
• Hi,
  
  I did another circuit where the the output voltage was coming out of a 555 timer #3 pin to a transistor with a relay (12 volts) working on  12 volts. It was fine.
  
  On this one how could I maintain the base voltage to 1 volt or so? When I clap with the pin 6  to the 5 volts ground. I get 3.75 volts and 30 mA.
  
  The relay is a 12 volts.

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• #1 Reply
  Posted by Paul Price on 12 Feb, 2014 19:24
• The base voltage cannot be set higher than approx .7V with your circuit> The ON base-emitter voltage of a silicon BJT sets this limit,
  
  But why try? With your circuit as shown it would work fine with just the resistor in series with the base.
• #2 Reply
  Posted by J4e8a16n on 12 Feb, 2014 19:44
• Quote from: Paul Price on 12 Feb, 2014 19:24

  The base voltage cannot be set higher than approx .7V with your circuit> The ON base-emitter voltage of a silicon BJT sets this limit,
  
  But why try? With your circuit as shown it would work fine with just the resistor in series with the base.
  

  
  I assume you take note that the bjt is at 12volts and the TTL at 5 volts...
  
  Well why does not this work ...?
  
  Thank you for your interest.
  
  JP
  
• #3 Reply
  Posted by J4e8a16n on 12 Feb, 2014 20:34
• It does  work 
  
  This app  square the input from the electret then add multiple waves in one long wave . It authaurize only one 'clap'.
  
  
  I am using an old electret (probably 45dB) with this application and it is not very efficient.
  
  It gives 3 volts at pin 7 .
  
  I have seen a $5 dollars electret  producing 60 decibels.  My problem is I have to clap at least at 2 feet for the application to work.
  
  Have any opinion on this?