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David, Arduino CPU pin impedance when configured as an analogue input is specified as 100MegOhms.? The charging source/sink is capable of 20mA and the measurement is a voltage ratio, essentially

Jeff, Tom and Jim, Thank you. I didn't think about archive.org. Got it. 73, Ray, W4BYG

An interesting article. I've built the Roman Black C Meter, which drifts a couple of pF over a short time, and the van Dijk code change, which seemed like it took a couple of minutes before the

Ray, While ARRL membership isn't for everybody, it does give you access to all their periodical publications. I'm glad that several years back I had enough money for a Life membership ... but only

I am looking for the article "How to design wide-band RF Quadrature Network" by G.W.Horn, I4MK QEX, November 1982. Anyone still have such in their QEX stash? Mine only goes back into the early 90's.

Hi David, Using an Injection Transformer, as in HP4342 Q Meter, uses known Power or voltage applied to a Constant Voltage Injection System. An example Injection Transformer Fixture shown in:

[email protected]> wrote: I might have misunderstood it. The adverts on the page, PDF and circuit in separate files didn’t make for easy reading. For small capacitors, unless the DC voltage is very

The example .pdf went AWOL on the first pass! PeterS???????????? G8EZE

A while ago I came across a really simple capacitance meter at ?? https://wordpress.codewrite.co.uk/pic/2014/01/21/cap-meter-with-arduino-uno/index.html I am usually sceptical about claims for such

I have no doubt that you are correct. I'm glad, though, that the farad won out over time. Faraday was remarkable, and deserves having two units named for him. --Tom -- Prof. Thomas H. Lee Allen Ctr.,

I don't think it was just the Navy that used Jars as the capacitance unit, it was the 'standard' in the early days, and it was some time before the farad gained popularity, jars can still be found in

Hi Gary, One tool that I found useful in tracking down spurii in an unstable UHF amplifier was the shielded pickup loop. I found out about this at an HP, RF, test equipment seminar in Canberra in the

Hi Guys, Some more on conventions in values. Leafing through some of my library of old technical books, I have found the following regarding capacitor designations: Practical Radio Communication,

Tesla's notes were the first time that I encountered the centimeter/centimetre as a unit of both capacitance and inductance. I see now the connection with the jar -- one jar is 1000 cm of capacitance,

Hi: In his Colorado Springs Notebook, Tesla talks about capacitors, inductors and RF signals, all with the units of meters. The capacitors were French Champagne bottles filled with salt water sitting

My one complaint about all commercial LISN units, and the measurement standards, is that their definition of common mode is flawed. K9YC has discussed this extensively. What they do is observe the

:) I wonder where the Royal Navy kept their standard jars… Tom Sent from my iThing; please forgive the typos and brevity

Which reminds me, I need to take 1111 pF of coffee to my amateur radio club. Dave -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... https://www.kirkbymicrowave.co.uk/ Telephone

I suspect that the Australian navy used Vegemite. Harvey

Farnell had some of those therompiles. I bought one of these https://uk.farnell.com/te-connectivity/g-tpco-033/thermopile-analog-to-05-7v-ntc/dp/3929821 It cost about 5x what the IR LED did, but is