Computer Technology

[Tin Can]

Thanks Randy. Actually I haven't used any tube amps but I have owned/used tube microphones. I've also wired up solid-state mics using a pinout but I wasn't sure what I was looking at wrt a tube. After reading around a bit I figured out what I'm looking for is just the "heater." Being mostly ignorant on how the tube functions, I didn't realize that is what the filament was referred to as on the pinout. Now to go find some wire .

Check for the required voltage. Safety glasses. Tubes are glass. When in doubt don't stand in water and use one hand, the other behind your back. That last one has saved my heart.

[Corran]

Good suggestions.

When I was little I used to line up AA batteries in a row on my floor and put a lightbulb at the end with a piece of wire running to the other side of the stack and see how bright it got after so many batteries.

Also I remember repairing a piece of audio gear and reaching into it and finding out that the capacitors still had a LOT of juice in them, ouch .

[chassis]

Bryan, nice work on the tubes. I would keep the black background and lower the main light, and bring it towards the camera and closer to the subject. Keep the fill to camera left and see what you get. Could be similar to what you have, but with more light on the tube bases. If you have modelling lamps you should be able to see it before exposing film. I like a pretty dark (black) background, so I try to keep the subject as far from the background as the studio will allow.

[Tin Can]

Yes, they do. My favorite preteen mistake was soldering a live circuit and putting a wire in my mouth to hold it.

Zippee!

I still test 9 volt batteries for strength with my tongue. Nobody does that anymore.

Good suggestions.

When I was little I used to line up AA batteries in a row on my floor and put a lightbulb at the end with a piece of wire running to the other side of the stack and see how bright it got after so many batteries.

Also I remember repairing a piece of audio gear and reaching into it and finding out that the capacitors still had a LOT of juice in them, ouch .

[Corran]

Thanks for the suggestions chassis! Lots to try.

Randy, I never do the 9V-on-the-tongue thing, I usually don't want to voluntarily zap myself , but I did use the 9V on the main tube in the front of the picture (811A) and it glowed nicely! I have to figure out if/how to incorporate into the photo. Some wire bits under the black background (it's just my darkcloth) or something. I have no sockets.

[barnacle]

Those 9v batteries can be clipped together pole to pole in a long series, with a *serious* jolt at the end - favourite trick for baby engineers

Bryan, the heaters on those tubes are most likely 6.3v or 12v (though there are a few valves with 1.5v heaters intended for portable radios) and you won't generate any extra volts anywhere just by powering the heaters. But the sneaky way to light 'em up is with an LED shining through the bottom of the valve, between the pins - an LED, series resistor of about 1k, and a low voltage source, say six volts.

That large tube - I don't think it's a display tube at all; it has a vacuum blip in the middle of the top surface by the look of it.

Neil (who is so old he knows a 12AX7 is the same as an ECC83... and did his engineering training when valves were still current and microprocessors was an optional module *after* the final exams!)

[Havoc]

I still test 9 volt batteries for strength with my tongue. Nobody does that anymore.

Nobody? Easier than finding the voltmeter. My previous collegue once did this with the client watching when checkng out an installation (they were used as third backup). Should have seen their faces.

Re the PDP 11/73 I have no idea what it ran, never had the courage to power it up.

[Corran]

Good idea on the LEDs Neil. I don't have any here to play with though.

I could only get the 811A to glow last night. I bought some 9V clip-on connectors and will wire it up and try shooting this again, along with some modification of the main lights, next week when I get the parts. Too bad Radioshack closed all their stores nearby or else I could just go buy some today...I need to research local electronic stores. I knew where they were in south GA but not up here.

[goamules]

Old analog and digital electronics are certainly beautiful. And it's amazing how expensive they were to design and buy, and then how quickly they became obsolete and were replaced by the next generation. I've worked on quite a bit of both types, and some of the military systems were quite beautiful and elegant, engineering wise. A countermeasures receiver I worked on in the Navy comes to mind. It had tuners that had a spiral track that were precisely adjusted by tiny eccentric cams every 1/2 inch along the track. A tiny wheel ran in and out based on the spiral. It was attached to a bar that made a resonant cavity larger and smaller (think the Star Wars scene in the garbage compactor).

I should have taken photos, all that stuff is in a dump, at the bottom of the sea, or in some boneyard now!

[Tin Can]

I would have a lot of industrial pictures of all kinds of very cool stuff, but cameras were banned anywhere in the factory. 24/7 I did take pics as part of my Lab work, mostly microscope work.

When they wanted images for advertising they brought in out of town pros to shoot with the best gear. In a one car garage inside the factory. Locked doors, covered windows. Paranoia runs deep.

Cummins would bring one floppy with the latest Diesel engine code. 3 guys would bring it and never let it out of their sight.