Velly cunning these chapanese.

Actually think it came out of one of the labs at Mas Uni, where the language MUMPS came from and is almost universally used in hospitals at the time and should think still is.. I remember programming in it.. made G Code look simple.
Bob

Quite right too! The original 555 had a few problems, high current consumption, taking large current pulses during switching, and was prone to double triggering. A lot of these issues were sorted out when the CMOS versions became available, although you need consider capacitor leakage carefully. Even worse are circuits where one 555 triggers another, and so on. Still, the 555 is better than the original TTL monostable, the 74121.

Regards,

Andrew

An absolute classic; I cut my teeth on these as a teenager (Start Trek Siren from an NE556) and came up with another use for one only a few days ago.

Microcontrollers are great, but 555s are the IC equivalent of wood vs plastic.

Neil

Cheek! I may be a youngster, relatively, but I can still speak valves. I was even taught about valves at college, on the grounds that the lecturer didn't understand these new-fangled transistor things. Here are a couple of pictures of the first working radio I made as a small kid, back in the days when electronics also required substantial metalwork. The radio covered the short waves, and was a superhet, very sophisticated! The top of the radio, showing the valves:

And the bottom, showing the point to point wiring:

Regards.

Andrew

Sorry – duplicate

Deleted

N

Edited By NJH on 26/08/2012 16:14:05

Edited By NJH on 26/08/2012 16:14:46

Hi, quite agree Neil, my Disco amp I built back in the 70's had EL84 output Valves, it was a stereo one and had a bootiful sound.

Regards Nick.

Hi there, Norman,

I used to travel by train from Walton-on-Thames to school in Woking. The Hackbridge & Hewittic Rectifier Company's factory was just down the road from Walton station and there were often mercury arc rectifiers like the one in your picture suspended on springs inside their open wooden shipping container sitting on a porter's trolley awaiting their train to wherever. When Sam, the porter, wasn't looking, we used to jiggle the trolley to get the rectifier bouncing on its springs and the pool of mercury swilling round the bottom of the bulb.

Later on, I worked at the EMI laboratories at Feltham; I worked in the analogue computer laboratory on what was at one time the largest analogue computer in Europe. A row of 19" racks loaded with operational amplifiers and time division multipliers, all thermionic technology. The three-phase feeder that came up through the floor next to the row of power supply units used to run warm to the touch. That computer was eventually given to Brunel University.

Best regards,

Swarf, Mostly!