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clapp oscillator

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meowth08

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Hi,

Design requirements:

12 Volts supply
output: 3 V peak to peak
frequency of oscillation: 1590 Hz

We already have a partial design.
It's a common emitter amplifier connected to the clapp oscillator.
We are getting approximately 8 Volts pk to pk on the simulation.
Can you suggest any other ways to accomplish the requirement?

I'll post our partial design later.
Many thanks.

By the way, I am measuring on top of R5.
I just added R5 and made it a very high value so it acts like open.
I wanted to measure below C6 and R5 should not be there
but I could not figure out how to add test points.
One thing more, I also want to see in the simulation
the frequency of oscillation without manually computing it.
 
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here you go:

Net (Node) labels (test points?) are placed using the Label Net tool in the toolbar (looks like a square bubble with an A.)
All nets are collected during simulation, and can be plotted even if you don't put an explict label on them. After a simulation run, put the Red Probe on a labelled or unlabelled node, and it will show you the internal node number, as well as the dc operating point.

To show the frequency of a plot trace, right mouse click on the trace label at the top of the plot pane. In the dialog box, Pull down 1st & 2nd in Attached Cursor. Click OK. That puts two superimposed cursors on the plot. Drag the 1st to the peak of the trace. Drag the second to a peak one cycle later. See my example.

Your frequency is off.

Use a real NPN; the generic one is a whimpy device.

Your circuit has some flaws.
 

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Hi sir,

The frequency should be 1590 kHz.
I'll try to do what you said in your reply.
I'll come back later to show what I have.
 
Hi,

Groupmates decided that we use a 9013 transistor.
I found this spice model on the yahoo groups.

.model SS9013 npn is=3.40675e-14 bf=166 vaf=67 ikf=1.164 ise=12.37f ne=2 br=15.17 var=40.84 ikr=0.261352 isc=1.905f nc=1.066 rb=63.2 irb=5.62u rbm=22.1 re=0.02 rc=0.7426 cje=3.53e-11 vje=0.808 mje=0.372 cjc=1.74e-11 vjc=0.614 mjc=0.388 xcjc=0.349 xtb=1.4025 eg=1.0999 xti=3 fc=0.5 Vceo=20 ICrating=0.5 mfg=Fairchild


Problem is, I don't know how to use it.

Added later: Ok now. library now updated :D :D :D
 
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Beta we measured on our transistor is 210. However, the model's bf=166. What do I do? Should I change it?

I don't know if the transistor is defective. Datasheet says its hfe min is 64 and max is at 202.

Nah! Now confused with hfe and beta. I thought they are the same. :confused:
 
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hFE is DC current gain. hfe is AC current gain. Beta is one or the other.
Each transistor has a different hFE even if they have the same part number so we design a circuit so that EVERY transistor works.
 
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