in my circuit, cap used are 100pF.. do you think it's too small?


On Tue, 12 Oct 2004 21:14:46 -0400, Herbert Graf
<mailinglist2@farcite.net> wrote:
> 
> 
> On Tue, 2004-10-12 at 21:00, Wan Zulhelmi Wan Ahmad Kamar wrote:
> > Hi, I've designed a 40khz bandpass filter.  When I simulate it on
> > pspice, the center frequency is 40khz.  However on breadboard, the
> > center frequency seems to be at 37khz and not at 40khz.  Can this be
> > ignored or do i really need it at 40 khz since my ultrasonic
> > transducer is at 40khz.  Any suggestions on what's the problem with my
> > circuit?  Here's my circuit.  Thanks in advance.
> 
> Remember, pspice is just a simulator, it uses models to approximate what
> happens in the real world.
> 
> It is entirely possible that a real world circuit will behave different
> from simulation. In your case I'd say it's working pretty close to
> simulation! Note that in pspice usually your components are "exact", a
> 100kohm resistor is exactly 100kohm. Unfortunately in real life this is
> rarely the case, a 100kohm resistor may be 98kohm, a 1uF cap might be
> 1.2uF.
> 
> There is no problem with your circuit, you just have to tweak the
> components a little to get the performance you want. Please do not rely
> soley on simulation, I have had cases where real world behaviour was FAR
> different then simulation (oscillators are a good device to confuse a
> simulator). TTYL
> 
> -----------------------------
> Herbert's PIC Stuff:
> http://repatch.dyndns.org:8383/pic_stuff/
> 
> _______________________________________________
> http://www.piclist.com
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist