Hi Rex:
Yup. It's really hard to get 50 of those 2 Ohm cables.
Brooke
Rex wrote:
On Thu, 06 Apr 2006 21:14:29 -0700, Brooke Clarke [EMAIL PROTECTED]
wrote:
to drive 50 a couple of Ohm cables
he he. Interesting typo.
I assume you really meant 2 50-ohm cables, rather than 50 2-ohm
,
it's within 5%.
HTH,
Robert G8RPI.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Brooke Clarke
Sent: 07 April 2006 05:14
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] IC for 1 PPS Output
Hi:
I've got the TVB 1 PPS PIC
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] IC for 1 PPS Output
Hi:
I've got the TVB 1 PPS PIC circuit working and would like to add an
output IC to drive 50 a couple of Ohm cables.
Need two outputs, the normal 1 PPS and also the 10 kHz output since I
think it would work
Dear Robert
You can either drive from A to B with the world finest German Maybach car
or also with a British Mini Cooper. May be the SN74128 50ohms coax-cable
driver is rather matched for this simple application !
Regards
Hans
___
time-nuts
Even more El cheapo (and also more ailable from your
spare parts drawer):
A fast hex inverter (74F04/74HCT04 etc...) wired in a
1-5 configuration (one input inverter driving five
output inverters) and then having each of the five
output inverters driving a separate 240 (or 220) ohm
resistor (keep
Brooke Clarke wrote:
Hi:
I've got the TVB 1 PPS PIC circuit working and would like to add an
output IC to drive 50 a couple of Ohm cables.
Need two outputs, the normal 1 PPS and also the 10 kHz output since I
think it would work with the SRS app note for making 1,000 TI
measurements in
Brooke Clarke wrote:
Hi:
I've got the TVB 1 PPS PIC circuit working and would like to add an
output IC to drive 50 a couple of Ohm cables.
Need two outputs, the normal 1 PPS and also the 10 kHz output since I
think it would work with the SRS app note for making 1,000 TI
measurements in one
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] IC for 1 PPS Output
Hi:
I've got the TVB 1 PPS PIC circuit working and would like to add an
output IC to drive 50 a couple of Ohm cables.
Need two outputs, the normal 1 PPS and also the 10 kHz output since I
think it would
Hi Brooke --
I meant to say that there was a separate 47 ohm resistor on each of the
inverter outputs, with the far end of those resistors tied together.
Last time this came up, there was an argument about why you wouldn't use
resistor values that in parallel would equal 50 ohms (e.g., 150 ohm
Paralleling CMOS inverters to drive time critical signals is not a good idea
because the inverters have skews between them, even if they are on the same
chip (die).
The skew for an improved version of the 74AC04 part (the 74LVC04) is
specified as up to 1.5ns!
Interesting enough, this
When I use 3 x 47 Ohm resistors and 3 gates the rise time seems about
the same, but the voltage into a 50 Ohm load increases from 2.5 V p-p
to 3.6 v p-p, so I tend to agree that's the way to go.
One thing was missing from your original question. What sort of receiver are
you going to use?
HI everyone:
last year I did a design requiring a full 5V out (higher than TTL) into 50
Ohms with real 50 Ohm source Z and 1 nS risetime.
For that I made an output driver using 15 V supply and high speed op amps,
two in parallel. But that would be an overkill for what you are doing.
See some
John Ackermann took my name in vain:
Hi Brooke --
The circuit I use is stolen from Tom Clark's TAC -- paralleling
several sections of a 74AC04 hex inverter through 47 ohm resistors.
For the current TADD projects, I'm using three sections that way, so
each chip gives me two outputs, and
Hi:
I've got the TVB 1 PPS PIC circuit working and would like to add an
output IC to drive 50 a couple of Ohm cables.
Need two outputs, the normal 1 PPS and also the 10 kHz output since I
think it would work with the SRS app note for making 1,000 TI
measurements in one second to better see
On Thu, 06 Apr 2006 21:14:29 -0700, Brooke Clarke [EMAIL PROTECTED]
wrote:
to drive 50 a couple of Ohm cables
he he. Interesting typo.
I assume you really meant 2 50-ohm cables, rather than 50 2-ohm cables.
I'll defer to others with more knowledge for a real answer to your
question.
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