[Heath] Information on 7492N (heath 443-34) binary counter please?

[Dean Naib]

Hi Bob,

 

I agree with you but the Heathkit manual text and the waveforms on the schematics clearly show it is resetting to 5 rather than zero.  Comparing the 74LS90 to the 7492N   (the freq meter uses both), the 90 has two sets of reset pins while the 7492N has only a single set which would seem to indicate that it only supports a zero reset.  I am going to assume the heathkit documentation is wrong.

 

Thanks,

 

Dean, K4DSN

 

 

From: Robert Groh [mailto:rgroh at swbell.net] 
Sent: Tuesday, February 22, 2011 4:01 PM
To: Dean Naib; Heathkit
Subject: Re: [Heath] Information on 7492N (heath 443-34) binary counter please?

 

Dean,

I think that it is extremely unlikely (based on 40+ years in electronics design and even involving the SN7400 family) that the A version of the SN7492N is any different in any significant way than the A version. Do a Google (or Bing or whatever) search for sn7492n and you will find many, many links to the datasheets.

73
Bob, WA2CKY

 

  _____  

From: Dean Naib <dsnaib at gmail.com>
To: heath at puck.nether.net
Sent: Mon, February 21, 2011 6:59:20 PM
Subject: [Heath] Information on 7492N (heath 443-34) binary counter please?




Does anyone have a datasheet for the 7492N?  

 

I have found sheets for the 7492AN but the heathkit manual for the IM-2410 freq counter explains that the reset signal should be resetting  the count to 5 but the 7492AN datasheet says the reset sets it to 0.  My  counter has a DM7492AN installed which I don’t think is correct.  The problem I’m having is that I am not able to read any frequency below around 50 khz regardless of amplitude.  The clock pulse coming out of the DM7492AN doesn’t match the wave form on the schematics, there should be a notch toward the end of the clock pulse caused by the reset of 5 but instead I’m seeing a full 0 reset and no notch being taken out of the clock pulse.  I would like to know if the 7492N does have a different reset then the AN version but I can’t find a datasheet for it.  Does anyone know ?

 

Thanks,

 

Dean Naib

 

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