Slide Rules

From: hilpert at cs.ubc.ca

Well, I assumed it was doing a simple V R ratio / sum-of-logs of two of the controls with a null-point balance with the third, however one of the sites on the web showed a bag of caps and transistors involved in the construction so perhaps it's using some AC principle, or that may be a mislead. I'm going to try to find the PE article in the library at the radio museum this afternoon. On 2013 Mar 10, at 11:50 AM, dwight elvey wrote: > I did some searching on the web but I was surprisedthat no one has > posted a schematic for it.Dwight > >> Actually, after giving it a little thought, it would use >> linearpots and scales. It would be voltage dividers and a >> balancingmeter.Remeber, a pot forms a ratio across a resistor.Dwight >>> From: hilpert at cs.ubc.ca >> >>> >>> That's what I was expecting, but looking at the dial (as much as one >>> can see in the photos), they appear to be linear, so I figured it >>> was >>> taking advantage of log pots (or is there a log/anti-log problem >>> there anyways?). Considering it more, a typical log pot may not give >>> an accurate enough log function to be very good for the task, so >>> you're probably right. Maybe there's another principle involved. >>> >>> Another web site refers to a popular electronics article with a >>> similar design (I think I've seen the article in the past) but >>> doesn't say which issue. >>> >>> >>> On 2013 Mar 8, at 8:58 PM, dwight elvey wrote: >>>> Actually it makes more sense to use alinear one with log scales on >>>> the dial.Dwight >>>>> From: hilpert at cs.ubc.ca >>>>> ---snip--- >>>>> >>>>> I like how the box says "As accurate as a slide-rule". >>>>> >>>>> Presumably it uses standard log pots, aka volume controls. >>>