There is an alternate method for finding Common Logarithms without the use of the L scale. This can be done on a slide rule by using the LL scales which are known as the Log-Log scales. For example, to find the common logarithm of the number 4, first move the right end index of the C scale over 10 on the LL3 scale. Next move the cursor hairline over the number 4 on the LL3 scale. Then read above it on the C scale that the common logarithm of 4 is 0.602. The reason why this works is because common logarithms have the base of 10. The number of interest is 4 in this example. The exponent turns out to be 0.602 read on the C scale. In other words, 10 raised to the exponential power of 0.602 equals the number 4. A logarithm is actually an exponent.
On the L scale for Common Logarithms, its midpoint is at 0.5. This location corresponds to the midpoint on the D scale which is at 3.16, because log(3.16) = 0.5.
Logan, if it seems like you'll be building a slide rule collection like your calculator collection, you might want to keep your eyes peeled for one of those Cleveland Institute of Electronics slide rules on eBay. They are a Pickett N-515-T and are geared to the EE user. Some appear at exorbitant prices but an occasional bargain shows up. K6WHP.
That's really interesting, I haven't yet caught the bug to collect slide rules but if I come across one that is specifically for EEs, I might have to begin!
There is an alternate method for finding Common Logarithms without the use of the L scale. This can be done on a slide rule by using the LL scales which are known as the Log-Log scales. For example, to find the common logarithm of the number 4, first move the right end index of the C scale over 10 on the LL3 scale. Next move the cursor hairline over the number 4 on the LL3 scale. Then read above it on the C scale that the common logarithm of 4 is 0.602. The reason why this works is because common logarithms have the base of 10. The number of interest is 4 in this example. The exponent turns out to be 0.602 read on the C scale. In other words, 10 raised to the exponential power of 0.602 equals the number 4. A logarithm is actually an exponent.
On the L scale for Common Logarithms, its midpoint is at 0.5. This location corresponds to the midpoint on the D scale which is at 3.16, because log(3.16) = 0.5.
Makes sense!
I love the juxaposition: using a sliderule but checking it with a Swiss Micros DM42--great imagery of old and new!
Logan, if it seems like you'll be building a slide rule collection like your calculator collection, you might want to keep your eyes peeled for one of those Cleveland Institute of Electronics slide rules on eBay. They are a Pickett N-515-T and are geared to the EE user. Some appear at exorbitant prices but an occasional bargain shows up.
K6WHP.
That's really interesting, I haven't yet caught the bug to collect slide rules but if I come across one that is specifically for EEs, I might have to begin!
Great video. Helped a lot. Thanks.