Gpapag, the TEK 475 is a pretty good scope, so long as you don't spend (forever) in fixing it. I use a TEK 485 on my bench, and love it. I had to repair it once, however. It lost its computer grade power supply cap! Still, I can hardly do without it. Bandwidth above 60MHz is important. Oscillations can happen in the 100's of MHz. Trust me, I have seen them.
Sync, what is the filter you are concerned with? Just give me a simple answer. In general, simple filters are easy, exotic filters are almost impossible. Back in 1974 I got a book, 'The Active Filter Cookbook' and it solved 90% of my problems then, and would today. However, for an exotic anti-alias filter, I hired my first PhD in 1974 to do it for me. Same would be true today. So again, what do you need? (in simple terms)
Hi John, nothing fancy with the filter,
just a simple band pass filter.
A high pass CR filter at 15kHz
A low pass RC filter at 30kHz.
Center Frequency 22.5kHz.
Cheers,
just a simple band pass filter.
A high pass CR filter at 15kHz
A low pass RC filter at 30kHz.
Center Frequency 22.5kHz.
Cheers,
Thanks for the pics George. I see the TEK. Not bad.
Oh then the WTF?
You mean that little thing on the desk?
Residing by the 9V battery?
The one with the (dating myself here too) wind up stop watch thing
on the top of it? So that isn't so bad? Even for a wind up hand held
mini scope. That is pretty neat.
Cheers,
Oh then the WTF?
You mean that little thing on the desk?
Residing by the 9V battery?
The one with the (dating myself here too) wind up stop watch thing
on the top of it? So that isn't so bad? Even for a wind up hand held
mini scope. That is pretty neat.
Cheers,
I bet most of the people in this thread have lab equipment far exceeding the value or their stereo.
Some stuff is affordable, but then again not... matter of perspective. Even though a 200mhz scope back in the day was hot ****, realizing today that a 500mhz would be best for your use and looking at the price will bring you right back to earth.
Some stuff is affordable, but then again not... matter of perspective. Even though a 200mhz scope back in the day was hot ****, realizing today that a 500mhz would be best for your use and looking at the price will bring you right back to earth.
Sync, you need a simple (how to book) However, you also need to know what the steepness of the slopes should be.
Hi John,
I have the values that I need and did the Bode plots online.
I linked to them in the thread I linked too.
For some reason I just can't get it to work
correctly.
How to books are good.
Cheers,
I have the values that I need and did the Bode plots online.
I linked to them in the thread I linked too.
For some reason I just can't get it to work
correctly.
How to books are good.
Cheers,
Don Lancaster's book: 'Active Filter Cookbook' is available from Amazon Books. It is about $35, but you might find one used somewhere. I highly recommend it to you.
For those looking for something easy to work with to get started, here are some resources at TI:
FILTERPRO WEBENCH Active Filter Designer | TI.com
https://focus.ti.com/lit/ml/sloa088/sloa088.pdf
http://www.ti.com/lit/an/sloa093/sloa093.pdf
Haven't tried it myself, but the designer app might be okay.
In any case, filter design is a big subject. Getting started can be pretty easy though, at least compared to long ago when some of us around here started learning about it.
He he. It’s the probe’s BNC connector.
I wish it was powered by winding a spring. (it draws 100mA from a 9V cell)
Re filter, as Markw4 said (more options than you want 😀)
https://webench.ti.com/webench5/power/webench5.cgi?app=filterarchitect&origin=ti_panel&filterType=Bandpass
George
Rapid practical designs of active filters by Johnson and Hilburn is the go to filter book. Shows how to calculate the values and build almost every type of active filter.
Every engineer who has worked with me and seen my copy has bought one.
Every engineer who has worked with me and seen my copy has bought one.
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@ Everyman,
Thank you for your suggesting. I bought all of them plus a few more used for about
$20. USD. They should arrive in a week or two, depending on location etc.
I just hope none mold/mildewed out as those go to the trash. They were all
labeled as used from good to better. Not a collector so good used is
okay with me. They will be put to good use.
@George, LOL I see the BNC now. Looking only at the small pic
it looks like a windup watch.
@John, got it and picked up some of Lancasters other cookbooks too.
@Ed, got it, looks to be good used prices for these.
Okay, back to working on part of the filter.
This should be pretty straight forward,
even with a JFET amplifier.
I've got something not right.... It should just work.
May all your designs work correctly the first time.
Cheers,
Thank you for your suggesting. I bought all of them plus a few more used for about
$20. USD. They should arrive in a week or two, depending on location etc.
I just hope none mold/mildewed out as those go to the trash. They were all
labeled as used from good to better. Not a collector so good used is
okay with me. They will be put to good use.
@George, LOL I see the BNC now. Looking only at the small pic
it looks like a windup watch.
@John, got it and picked up some of Lancasters other cookbooks too.
@Ed, got it, looks to be good used prices for these.
Okay, back to working on part of the filter.
This should be pretty straight forward,
even with a JFET amplifier.
I've got something not right.... It should just work.
May all your designs work correctly the first time.
Cheers,
Thanks Ed, THAT is the book I used way back then.
Sync, you will find vital practical info in Lancaster's books. He wrote for the rest of us, practical designers, not just the academics. Of course, they are quick and dirty solutions, and other more complex textbooks can sometimes be useful, but usually there is too much complexity, math, etc, when what you want is a simple direct solution.
Sync, you will find vital practical info in Lancaster's books. He wrote for the rest of us, practical designers, not just the academics. Of course, they are quick and dirty solutions, and other more complex textbooks can sometimes be useful, but usually there is too much complexity, math, etc, when what you want is a simple direct solution.
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