So this means we need a 90+ group also?
Being serious for a minute, it seems most regular contributors on this site are 60+, retired and still addicted to their lifelong hobby/industry/employment/business… call it whatever.
I was interested in how accurate my observations are, that is all.
JLH died back in 2004
I suppose there are a lot of veterans like me on this forum. Developers are mostly younger, apart from the founder JP Charras
Hmm… the reference to “JLH” and DIY electronics projects just pulled up a memory from the distant past when I was a kid growing up in the '80s.
I remember a project I never got anywhere near finishing - it was a frequency counter that was featured in QST back then. I ordered the PC boards from one place in Colorado, and one of the smaller boards was a preamplifier, and which had the marking “JLH 876” on it.
Possibly him. While best known for audio, he did publish buffers and also a couple of VHF tuners on ETI and WW
Really…I never heard of him. The 3 letters remind me of KLH which company made decent audio equipment in the 1960s. My parents had a KLH compact stereo (combined turntable, FM tuner, amplifier in a box not much bigger than the turntable alone.) it was pretty good.
Yes that is close to my understanding. It might be alumina; there are better and more expensive alternatives such as diamond film (??). I remembered some sort of nitride ceramic and google tells me aluminum nitride as an alternative which is probably between alumina and diamond film.
The Apollo Guidance Computer was implemented using RTL gates. The Smithsonian National Air and Space Museum calls the AGC the first computer based on silicon integrated circuits.
I’m too young to have played with RTL gates; my first introduction to digital design was Donald E. Lancaster’s TTL Cookbook. A few years ago I was offered (and accepted) a set of four of Don’s Cookbook series: RTL, TTL, CMOS, and IC OpAmp. I don’t think DTL was around long enough for a DTL Cookbook to be published.
I also have these. Honest, well written books on the subjects.
Yes I consulted the online version of the RTL Cookbook to decipher the innards of the nixie thermometer I modified. It was interesting to learn that decade counter schemes other than the 1-2-4-8 configuration have been used. The thermometer used a 1-2-2’-4 scheme.
One of the things which most attracted me to electrical engineering: Unlike politics and some other professions, dishonesty cannot go far. The hardware calls out the lies.
When I read (a little) into RTL and DTL; I wonder whether maybe a lot of it was done with discrete transistor circuitry rather than ICs. I think I remember seeing a pcb which had one or two discrete bipolar flip flops on it. Of course there was no surface mount; all through hole. Hmmm…let’s do 100 MB of RAM with discrete bipolar flip flops. As bad as that sounds, vacuum tubes were worse.
For me I think KiCad and this forum is something of mixing electronics which first sucked me in when I was a kid, along with (dare I say?) a form of social networking vaguely like being back at work in an office. I am actually un-retired now, but my job is fully remote. So the social part of it is, well, not the same.
I think before integrated circuits there were disintegrated circuits 
, i.e. circuit modules. IC could also stand for Indiscrete Circuit. Making it with lithography was the next step.
One of these years I’ll have to give up gerbers for gerberas. My ignorance of so much stuff is vast. 
Don’t forget relays folks. They belong somewhere in the mix.
My first introduction to the telephone network was in the very late 1970s.
Slow responding relays, fast responding relays.
Make, break, make before break, make after break contacts. Up to 12 sets per coil. Millions of them.
I remember being surprised when an exchange serving 15,000 lines at peak time (9am Monday mornings) would draw 3,500 Amps @ 50VDC. You could smell the arcing of the contacts.
I had a colleague with a side business employing prison labour to recover the precious metal from old exchange relays
Holy smokes. I emphasize the smoke. Be aware that you can also implement logic with compressed air.
Ah yes telephone relays. 48V colls I think. As a kid I was given a couple of discards by a relative who worked for the telecoms authority. I made a darkroom timer using a octal base valve from an ancient radio, a potentiometer and capacitor for the time delay and a neon bulb to fire when the required voltage was reached to make the valve turn off the relay.
And staying on the TO-220 topic, I remember the TIP series. I made an amplifier with a complementary pair for the power stage.
@ Bobz:
beside the nice excursion on the history of digital logic a (hopefully) final response on your remark:
You should distinguish between housing/case and device.
The TO220 case was and is a very common housing for devices in the medium power range: transistors (bipolar, unipolar), thyristors, triacs, power regulators (78xx, 79xx).
Depending on the devices (and the technology behind this device) there are various configurations for the electrical link to the case → check the device datasheet
I just checked the KICAD standard library: case is not linked with any pins. So in case you need to establish this link, you have to make your own variant.
Got enough of this nonsense, huh? 
Yes. But seeing all those choices (of which only one is correct) in the datasheet makes me long for the simple dimension drawing of a TO-220 with pins labeled B C E for the bipolar transistor. It reminds me of our local recycling calendar which has colored bars everywhere and tells me nothing.
Complementary pairs work better than insultory pairs which usually get hot and go up in smoke. (Spelling error is intentional.)
I remember seeing TO-220 packages with a full metal back… was that common at one time? By metal back, the encapsulated portion sat on top of the tab portion, it did not wrap around the edges.
I remember one of my company’s customers had a standing directive to replace ANY of these metal-backed transistors (TIPxx) that we encountered on an audio amplifier board we built for them back in the late '80s.
I have a few! They are TIPXX made by TI. In my memory, no other company had that package style. Do you think there was some valid reason why your company’s customers wanted to replace them?
I do not think that the TIP transistors were good for audio amplifiers, but I say that because of low Hfe gain and low bandwidth, with a unity gain bandwidth of maybe 1 MHz.
Another unusual TO220 package transistor was the D44 (red colored NPN) and D45 (green colored PNP) series made by GE. In addition to the red and green colored (silicone?) plastic, these transistors had gold plated leads which were round in cross section, approximately like AWG20 wire. I have a few green D45.
These days I think that you can buy newer transistors with the same numbers, but they are in (no doubt much cheaper) common garden variety TO220 packages.