Cool! As a teenager I built a Heathkit IM-11 back in the 1960's, learned a lot about vacuum tube circuits from the build, and got lots of use out of it. The RCA VoltOhmyst looked familiar to me as well. Sometime in my undergrad years (B.S.E.E.) I gave it away to an aspiring young EE.
those of us, for most if not all measurements lived in a world of plus or minus ten percent. mirror not necessary. as to only $15.oo : minimum wage was less than 1 dollar. i couldn't afford a new one. today any autoparts store's got one for $10-$30 that can measure to 1% and has a pretty good repeatability and runs on batteries which vtvm's did not, usually.
I still have my Heathkit V7-A VTVM which I built in 1957 working. It's a close cousin to the RCA who had all the standard tube circuits in their tube manuals. The Heathkit has a db scale and no separate scale for the 1.5V range. In the 60s I replaced the 1.5V D cell for the ohms function with a power supply kit sold for that function and the zero and ohms pots with the vernier (planetary ball) pots availble from Heath which made setting zero and ohms far less touchy.
Those wax covered paper tubes are hiding the reistor values underneath them. Who knows what purpose they serve. If you look at the schematic, there are very few caps in the circuit.
I'm impressed that all my Heathkit tube equipment from the 50s and 60s still functions very well indeed. The only repair I've had to do is replace a resistor in the AG-9A audio generator which had too low a wattage rating causing value shift and 4% harmonic distortion. After that fix the distortion went down to under 0.02%.
I still mourn the death of Heathkit, like a long lost friend. They got me into electronics after all.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.