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Ancient circuitry
On Jan 18, 11:31*am, I am Tosk
wrote: In article c9511ebc-d7f2-449a-9d90-c55f2b828712 @m3g2000yqf.googlegroups.com, says... On Jan 18, 8:36 am, Canuck57 wrote: On 17/01/2010 4:18 PM, Eisboch wrote: "Del wrote in message ... wrote in message ... On 16/01/2010 6:17 PM, wrote: On Sat, 16 Jan 2010 14:05:54 -0800 (PST), Frogwatch wrote: Here at work, we are repairing the vacuum control circuitry for an electron microscope made in 1979. It has 6 SN7400 chips. If I remember, these are quad 2 input NAND gates. 2 of them have gone bad because the heat sinking of the board is not very good, you can see heat discoloration on the board. Back in 1974, I was 18 and was experimenting with making computer circuitry trying to make a computer cpu with a calculator chip and a buffer made from a bunch of 7400 gates as memory flip flops. I never got rid of all those old chips and still have several tubes of them unused. Now, 36 years later, I find a use for them. Never throw anything away ;-) There are still plenty of places that still stock these things. I never took the TTL plunge because I had IBM parts to play with but I have made a lot of CMOS (4xxx) stuff. Couple that with a big SSR and you can run humongous stuff straight from CMOS. (like my 11kw spa heater) Same deal, just that you are likely a few years yonger. Every TTL has a CMOS counterpart in time and CMOS was a better/newer evolution of the TTL. Used both myself but mostly TTL. Was fun to tinker with those chips on bread boards. A joy many today will never know. I always wondered if the US government got a hold of an ancient space ship and reverse engineered the electronics we have today. As we accelerated down this path about as fast as socially possible without regards to the hardware. I remember saying to people at the time that it is unlikely I will retire before we see a 4ghz computer with 4 CPUs and 4gb of ram and 4gb of hard drive as a commodity system. Only 4ghz CPU stands between me and retirement. Bu the rest is history. You are a couple of years overdue. Put in those papers. Depending on your definition of commodity of course. http://www-03.ibm.com/press/us/en/pr...ease/21580.wss I remember TTL logic being the rage in the late 70's. The problem for electrically noisy industrial applications was that a "high" was about 3.8 volts and a "low" was around 2.4 volts. A TTL logic based controller would work fine in the quiet lab, but when it was used in a real application and subjected to harsh RFI and EMI environments, there was no way of telling what it would do. It didn't take much of a electrical spike or some RFI to completely screw up the logic. CMOS at 12 volts worked much better. Vacuum tubes worked perfectly. (and still do). Eisboch Can't say I miss tubes. RF and heat burns... But good heaters.- Hide quoted text - - Show quoted text - I miss them in my guitar amp! I got them in mine... I bought a modern Fender Champ and it is a tube job. There is a second channel which adds solid state circuitry to emulate other amps, but played straight, it's a tube.. Scotty AKA Plays With Sharks- Hide quoted text - - Show quoted text - I'm holding out for an old vintage Vibrolux! |
#22
posted to rec.boats
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Ancient circuitry
"Loogypicker" wrote in message ... I'm holding out for an old vintage Vibrolux! Too bad. Just sold one cheap. Eisboch |
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