Sean,

I read this post and wanted to ask you about the frequency counter portion
of your project.
I need to measure a frequency range of about 2 Khz to 4 Khz to as small a
resolution as
possible, while still sampling as fast as possible.  I see your frequency
counter goes down
to 15 Hz.  What I wanted to ask you is what is your sampling period at the
low frequency end
of the range?   And is the software based on an Ap Note from Microchip, or
is it one of your
own?  Laso, do you perform any floating point math?  And if so, what
routines are you using?
I'd appreciate it if you would enlighten me and possibly share your software
for the counter
portion of your project.  Please RSVP


Thanks and Regards,


Jim
-----Original Message-----
From: Sean H. Breheny <shb7@CORNELL.EDU>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Sunday, October 17, 1999 12:59 PM
Subject: Re: RF High-Isolation Switches


>Hi all,
>
>Thanks for the help on the switches. I think I will use Mike Keitz's
>suggestion (given to me in a private reply), to use a DPDT switch (which I
>think will fit into the hole already drilled in the case).
>
>The actual application is a frequency counter and function gen in one case.
>You can switch the source of the freq. counter between the ext. input and
>the function gen. Because the function gen needs to operate even when the
>counter is connected, I cannot simply ground the function gen to isolate it
>from the counter. SO, the DPDT switch will allow me to connect the gen to
>the counter indirectly,and ground the indirect line when not in use.
>
>The frequency range is from 3Hz to 16Mhz. I can't work in a 50ohm
>environment because the amp input needs to be high impedance, so that it
>won't affect the external circuit that it is measuring. The function gen
>output is 50 ohms, however.
>
>BTW, to those who remember the thread on using 7404's as linear amplifiers,
>which was months ago, I finally did get it to work by using 74HCU04's,so
>yes,the answer was unbuffered gates,in addition to NOT using gates with
>adjacent pins (i.e., when using more than one on the same chip, skip a gate
>inbetween,and ground its input).
>
>When I have some pictures and schematics to show, I will put it up on my
>web page. Originally, I planned on including a dual channel power supply in
>the same case. I ended up building it separately,and it is also completed
>and should be documented on my page in the not-too-distance future.
>
>Thanks to all,
>
>Sean
>
>
>
>|
>| Sean Breheny
>| Amateur Radio Callsign: KA3YXM
>| Electrical Engineering Student
>\--------------=----------------
>Save lives, please look at http://www.all.org
>Personal page: http://www.people.cornell.edu/pages/shb7
>mailto:shb7@cornell.edu ICQ #: 3329174