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???
01/19/05 16:51
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#85313 - Load Lines
Responding to: ???'s previous message
Hi Rob,

If you are heartset on using a discrete transistor circuit to amplify the signal, my first suggestion would be to look up how to do load line analyses of your transistor, and then do them. Be sure to do both the DC and AC load lines. If you do these analyses you should both identify the problem and see how to fix it. Moreover, you will really impress whoever is grading your project. Also, be prepared to possibly use multiple stages, or maybe a darlington input stage. I haven't done the analysis so I don't know if you'll need this or not, it's just a possibility depending on the Hfe (beta) of your transistor.

If you just want the signal, take Erik's advise and use an op-amp.

Good Luck,
Joe

P.S.:
I am feeding the 40khz signal through a 5k resistor to the gate, ...


A bipolar transistor has a base, not a gate. If this is for a grade, this is the kind of mistake that can really cost you.

List of 36 messages in thread
TopicAuthorDate
amplifying port output signal to 12v dc            01/01/70 00:00      
   Transistor driving            01/01/70 00:00      
   use an op-amp            01/01/70 00:00      
      Hardly -            01/01/70 00:00      
   Tell us the name            01/01/70 00:00      
      micro and transistor            01/01/70 00:00      
         RTFM            01/01/70 00:00      
         Atmel T89C51CC02            01/01/70 00:00      
            it should be fine            01/01/70 00:00      
               Both of them.            01/01/70 00:00      
            stop guessing            01/01/70 00:00      
         Seems to be an impossible situation            01/01/70 00:00      
            Seems to me            01/01/70 00:00      
               thats right            01/01/70 00:00      
                  google            01/01/70 00:00      
                     i have the data sheet            01/01/70 00:00      
                        maximum            01/01/70 00:00      
                  OK That's right but...            01/01/70 00:00      
   Load Lines            01/01/70 00:00      
   Basic transistor theory            01/01/70 00:00      
      5 volt wave to base            01/01/70 00:00      
         TTL ?            01/01/70 00:00      
         maybe it's an error...            01/01/70 00:00      
            yes            01/01/70 00:00      
               TO92            01/01/70 00:00      
                  its working!            01/01/70 00:00      
         No current            01/01/70 00:00      
      The TR is not saturating ??            01/01/70 00:00      
   converting 5volts 12 volts            01/01/70 00:00      
      Pithy phrase            01/01/70 00:00      
   Seems making Ultrasonics...            01/01/70 00:00      
   Push-pull needed?            01/01/70 00:00      
   5volts to 12 volts            01/01/70 00:00      
      Inversion...            01/01/70 00:00      
    ttl amplification            01/01/70 00:00      
      did you read the 3rd post ?            01/01/70 00:00      

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