[sdiy] EH frequency analyzer

[Samppa Tolvanen]

Hi, Paul, all..


On 8/8/08, Paul Perry <pfperry at melbpc.org.au> wrote:
> >From the designer of the LM13600 & LM13700:
>
>  " After layout,design management decided to just go ahead and make it a
>  product. First silicon work even with very unusual beta. This last fact
>  explains why both the  LM13600 and LM13700  came out together. Control of
>  beta was not tight at the time and all transistors needed to be biased up
>  with currents well above the leakage current levels in the process. One way
>  to do that was to use area scaling to force the beta of the output
>  transistor in the darlington to 50. That what was used to the LM13700.The
>  other method involve feeding some of the control current back to the
>  darlington. At the time, this enabled the  LM13600 to have usable dynamic
>  range well above 96dB."
>

Could You link to this information, please?

>  I think the NE5517 is a LM13600 knockoff. Certainly seems identical to me.
>  And it's staying in production, because Philips asked On Semi to make them,
>  after the Philips plant burnt down.
>  It's kind of annoying, because On Semi is a spin off from Motorola, so
>  obviously they have the skills & gear to make all the other stuff missing
>  from this era, but not enough people give a shit.

It SHOULD be, at least. I think Mr. Bissell has commented on this
one.. Not I'd trust him :D

Samppa