[HomeBrew] Strange anomaly of a 74LS90

[kevin@kd1j.com]

Phil,

  I saw something similar with some bi-directional versions
of the 'LS90.  In our case, it was the 74LS192.  
  We blamed it on the 'no-name' label.  Don't remember who
the MFR was, but it sure wasn't TI, Motorola, etc...

  I pity the poor 'newbie' that runs into things like this,
while trying to get their 'first project' up and running!
  It could really discourage a fellow.

73,

Kevin


  <><><><><><><><><><><><><><>
  Amateur Radio Station - KD1J
  Kevin D. Jacobson
  27 Ridge Road
  Wallingford,    CT.    06492
  e-Mail:       kevin@kd1j.com
  Website: http://www.kd1j.com
  <><><><><><><><><><><><><><>

=================================================================


On Fri, 16 Apr 2004 23:14:17 -0700, "Philip Atchley" wrote:

> 
> ** Please do NOT cross-post messages to multiple mailing lists on the "To:"
> or "CC:" line of the e-mail message. **
> 
> Hi,
> Today I finished building a Xtal Calibrator to use with my Hallicrafters
> SX-71 receiver.  Kind of a "super calibrator" with both 5 MHz and 4 MHz
Xtal
> oscillators and dividers to give me markers at 5, 2 & 1 MHz intervals as
> well as 500, 100, 50 & 25KHz.  (Only one of the two Xtal Oscillators are
> active at a time). I derived the 500 kHz by dividing the 5MHz in a 74LS90,
I
> could just have easily divided the 1MHz by two in a 74LS74.
> 
> Anyway, after I built it and proceeded to check it out, everything tested
> out OK, EXCEPT for the 500KHz output (5MHz divided by 10 in a 74LS90 decade
> divider).  That one gave me an output of about 625 kHz.  Quick math showed
> that it was dividing by 8 instead of 10.  Double checked all the wiring and
> connections, it was good.  I plugged in another 74LS90 (glad I used
sockets)
> and it worked PROPERLY!
> 
> Has anyone here seen a decade divider (consists of a divide/5 and a
divide/2
> divider) that divided by 8?
> 
> 73 from the "Beaconeers Lair".
> Phil, KO6BB
> 
> DX begins at the noise floor!
> Merced, Central California
> 37.18N  120.29W  CM97sh
> 
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