Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Brooke Clarke
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Robert Atkinson
, 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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Jeroen Bastemeijer
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Hans H. Jucker
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Normand Martel
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread John Ackermann N8UR
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Bill Janssen
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Mike Feher
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread John Ackermann N8UR
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread SAIDJACK
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Hal Murray
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?

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread buehl
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-07 Thread Tom Clark, K3IO (ex W3IWI)
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

[time-nuts] IC for 1 PPS Output

2006-04-06 Thread Brooke Clarke
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

Re: [time-nuts] IC for 1 PPS Output

2006-04-06 Thread Rex
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.