400 Hz

Kieth another advantage of 400 cycle is that mag amps which predate transisors worked real well with 400 cycles and were a lot smaller than with 60 cycle units.

I believe I built the first transistorized switching regulator to preregulate the power for a 400 cycle test set we were building for Boeing back in 59. It was at the ElectroSolids Corp.

It used an interesting inductor which allowed the output voltage to go to 0 volts in over load at 1/3, on time, pulse width.

I have never seen that configuration used , after that, except in some supplies I designed.

I believe a fell named Dr. Siegfried Lindener came up with that inductor. Last I had heard of him some 50 years ago was that he had gone back to Germany.

He was the one who taught me the secrets of inductors and transformers.

My first patent application was a tapped inductor that gaurenteed the turn off of SCR's by reversing the voltage across them. Got a $100 bonus for that one.

. . I DO NOT FOLLOW MANY OF THESE NEWS GROUPS To answere me address mail to snipped-for-privacy@aol.com

Sure, but they went away from phase-controled regulators, in favor of switchers after the 3080s, IIRC. I.e. the 3090s main supplies were switchers. 400Hz has many advantages that outweigh the conversion for monsters like these.

The 60Hz was all in the power/thermal controls (supplied TR packs for the control/sequencing logic) and other ancillary widgets, IIRC.

Larger IBM 360 computers (1968-1972) used 5000 Hz, 120 V single-phase power to supply all the computing circuitry. They used a "converter- inverter" to turn 208 V 50/60 Hz 3 Phase mains power to DC, then inverted it with a fast SCR inverter. The 5 KHz whine was almost earsplitting when you walked behind the main CPU cabinet. All the modular power supplies in the machine ran of the roughly regulated 5 KHz power. They used very thin transformer laminations, and the magnetics and filter caps were VERY small for the day. This would apply to the

Large 370 mainframes used 415 Hz 3-phase power from a GE motor-generator set. The advantage of these was the rotary inertia in the MG set, that could power the machine for a few seconds when line power failed. it was pretty wierd to be near the machine when there was a short power blip. All the fans in the machine would fall silent, but the lights would keep flickering away on the console. They used some really inventive circuits in the regulators, too. They called this the electronic capacitor. It was a big inductor that circulated current during the line peaks. At the time of the dips between peaks, a transistor turned off for a moment, allowing the current in the inductor to be added to the current flowing out of the filter caps. The currents in these things were huge, several hundred amps from each supply at -2 and +3.3 V. The logic was similar to standard ECL.

Jon

No, 3600 RPM was fast enough for nearly all disk drives of that date. If they wanted it a bit faster, it would be no big deal to change the pulley diameters. The windage losses of 14" disk platters were already huge at 3600 RPM, you really couldn't spin a big stack of them at 10,000 RPM without reducing air pressure or supplying process cooling or they'd literally burn up!

Jon

And the Mod 30. That little blue box was an inverter/converter too. ;-)

You sound like another old CE ;-) I retired in 96 as a Specialist with a "minor" in IPR

Not CE. Designed 'em in P'ok (303x widgets, 3090 Power/thermal control system, 902x Crypto).

Not yet... (well, maybe the IPR part ;-).