Other Web Sites Related to HP History
updated June 10, 2026
The links listed below are to other web sites related to HP History. Some of the web links are moving targets. I check these from time to time and find some of them dead only because of a subtle change in the URL when a website was reorganized.
Here is one (there used to be more) direct internal links to the HP web site
One sub page is devoted to the history of the HP200A and has quite a bit of information I have not seen anywhere else. The page was posted in Jan. 2002 which was the 60th anniversary year of the patent William Hewlett received for the audio oscillator in 1942. This particular oscillator is supposedly the first one Bill assembled for his master's thesis at Stanford. That unit would have been for demonstration and not for production. There are several interesting things to note about it:
- The variable capacitor has a right angle drive. That was not the case for the production 200A, B, C, and D units -- they were straight shaft only.
- There are only four vacuum tubes. The production versions had five tubes. However, what is identified as the light bulb may be a tube instead. The picture has too low resolution to be sure.
- There is only a power transformer. There is no audio output transformer as was on production units. This might be consistent with only four tubes with only one tube used for the output amplifier.
- Although the 1939 schematic shown on the page has such low resolution that it is nearly impossible to read but I can make out that there are five tubes and an audio output transformer shown. But that is a later version of the original thesis unit.
- The tuning dial shown appears to be from a production 200B unit.
- The red and black output jacks are not the originals -- those would have probably been lost/worn over the years and would have been replaced.
The last paragraph has a subtle error concerning the HP200CD (the best known of all the HP oscillators) as a replacement for the HP200A. The HP200AB was the direct replacement for the HP200A and HP200B in 1952 (not 1953) and was an improved version covering the combined frequency span from 20 Hz to 40 kHz and could deliver about one watt of power to a 600 ohm load. Similarly, the HP200CD replaced the HP200C and HP200D also in 1952 but with an improvement in the output power -- approximately one watt as compared to only about 100 milliwatts for the C and D units and also a much wider frequency range. The HP200CD had a frequency range from 5 Hz to 600 kHz as compared to the 7 Hz to 200 kHz covered by the C and D units. The HP200CD (designed by Barney Oliver) achieved the wide frequency range by using a push-pull version of the Hewlett design and also used two output transformers -- one for low frequency and one for high frequency. With its frequency range wider than covered by the A, B, C, and D units the HP200CD effectively replaced them all. The HP200AB was last listed in the HP1975 catalog. The HP200CD was last listed in the HP1985 catalog. This 33 year run of a product is truly remarkable. All of these oscillators were based on same concept developed by Mr. Hewlett in the late 1930s. They were all built with vacuum tubes and used a lamp filament as the amplitude stabilizing element. So an HP200CD of 1985, the last HP oscillator based on vacuum tubes and to use a lamp filament for amplitude regulation, is very closely related to the original HP200A of 1939. The total manufacturing run of this concept then extends from 1939 to 1985, or 46 years!
Here are some direct internal links to the Agilent web site
Bill Hewlett biography
Dave Packard biography
Company time line
Other web sites with a variety of information: Some of these are deep links and others may only be available temporarily. If the web page is not found, try backing up by deleting pages from the end until you connect to something. A reorganization of the web site may have changed the address.
http://www.antiqueairwaves.com/ This is a great site if you are looking for information about old radios and electronics. There are numerous links here to just about everything involving old electronics. You could spend hours looking at all this stuff. A related site by the same owner is
http://www.stevenjohnson.com/ and you can find even more information including schematic diagrams, etc.
http://www.philbrickarchive.org/ "This site is a free non-profit repository of materials from GAP/R George A. Philbrick Researches, the company that launched the commercial use of the Operational Amplifier in 1952." (quoted from the site)
http://www.xcvcorp.com/Electronics%20Museum%20HTML.html
Links to other web pages on this site
https://www.kennethkuhn.com/hpmuseum This link takes you to the main HP Museum page.
https://www.kennethkuhn.com This link takes you to the main page of my personal web site where you can access a variety of information.