From: user@example.net   
      
   On 2/10/2026 3:41 AM, John R Walliker wrote:   
   > On 10/02/2026 07:05, Bill Sloman wrote:   
   >> On 10/02/2026 10:52 am, Christopher Howard wrote:   
   >>> Hi, I was wondering what is the cheapest (and hopefully, simple to wire   
   >>> up) way to get an analog square function. I.e., input a voltage x, and   
   >>> get voltage x^2 out. Or x^2/10. Or some reasonable approximation of   
   >>> either of those.   
   >>>   
   >>> The standard trick is to feed the voltage into both inputs of a   
   >>> multiplier chip. But even those AD633 chips are tough to afford on my   
   >>> budget (around 20 USD each).   
   >>   
   >> The late Jim Thompson's MC1496 is a lot cheaper - if a lot nastier - and   
   >> Digikey has it for $0.35 on cut tape.   
   >>   
   >> You'd probably need to trim out offsets to get any kind of accuracy   
   >> for low level inputs. The MC1495, which was closer to a proper   
   >> multiplier, is now obsolete.   
   >   
   >   
   > Another possibility is the LM13700 which comes in a dual in line   
   > package so it is easy to wire up.  You may need some extra   
   > components around it.   
   >   
   > https://www.ti.com/lit/ds/symlink/lm13700.pdf   
   >   
   > John   
   >   
      
   It works pretty good for squaring, see e.g. figure 24/25:   
      
      
      
   Drive ports Vi and Iabc with a current and you get Io = [Iabc*Ii]/Id.   
   Feed Io back to Id and you can get a square root while you're at it!   
      
   --- SoupGate-Win32 v1.05   
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