If you had one what would you use it for

I was Analog Guru at GenRad Portable Products Division, Phoenix, from

1977 to 1987. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy

nately

a

me

=A0 =A0 =A0 ...Jim Thompson

=A0 =A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0 =A0|

=A0 =A0 =A0 =A0 |

=A0|

|

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

My friend worked out of Boston. I think he must have left around 1977 or so (it would have been shortly before going public). He said that he worked there for many years prior to Gen rad going public, and they paid many of their engineers in shares of the company. He was one of the engineers with quite a lot of this stock. There was a stipulation that the stock must be sold back to the company if the employee left the company. Just prior to the company going public, they essentially fired several of these high engineer holders of company stock and forced them to sell at the agreed upon rate back to the company. Some short time later, the company went public and those shares that he had to sell back would have been worth 250K (that is number I think he said it cost him in 1970 something dollars)

Have you heard this story?

[snip]

I don't know when they went public. I do know that I lost $40K overnight in the infamous 1984 debacle :-( ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy

[snip]

GenRad upper management had trouble coping with the 20th Century. They also didn't like a upstart division out there in Phoenix, making something different, that wasn't in a wooden box, showing them up by making consistent profits... so they shut us down :-( ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy

rtunately

a

is

nd a

rce

time

=A0 =A0 =A0 ...Jim Thompson

=A0 =A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 =A0 | =A0 =A0 et =A0 =A0 =A0|

=A0 =A0|

=A0 =A0 =A0 =A0 =A0 |

=A0|

=A0 |

=A0 =A0 =A0 ...Jim Thompson

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

I was working with this guy at Raytheon in 1984. So he did not experience that debacle.

It was good fun working with him. He was at the vert tail end of his career, and I was at the beginning of mine. Most of my peers were doing digital and computer stuff. I was doing Rf and the big cell boom had not taken place so I was working with all these old guys. Several had worked on radar duing WWII. They worked at the radar lab at(I think) MIT.

It was quite fun, I would work for 4 hours, listen to war stories for

4 hours and then go home at night and study for four hours to actually learn the stuff I was already supposed to know but did not feel I had learned very well in college.

Sounds like when I was young... work all day, then go home, eat dinner with wife and kids, then doodle electronic ideas all evening, all the way thru Jack Paar ;-)

BTW: I covered all my expenses, beyond the basics provided by my MIT Alumni Fund National Scholarship, by working as a technician at MIT's Building 20 ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Cranky Old Git With Engineering Mind Faster Than a Speeding Prissy

Yes 0.1fT per root Hz at about 100Hz. Carefully avoiding trying to measure it at a multiple of the mains etc.

Did you perhaps mean pico amp?

Bingo! we can't talk details here.

ly

The measurement volume is only a few mm across so it may work for the job but yes thermal or just a DVM tracking the drop in the trace is simpler.

ET

ly

Not a bad idea. The person would have to hold still in a very well shielded room but it would be less bothersome than an MRI.

ely

Yes.

Not cooled. It is heated but not all that hot.

Many layers. We need the field to be under about 100nT for it to work. Lower is better.

It has a bandwidth of a few 100 Hz. The output is analog voltage.

The little circuit with a Sonalert, 4 9V batteries and an SCR does a dandy job of that.

tely

No supermagnetic. Infinite mu. It must not conduct at all.

John

unately

Unfortunately, I think it only applies "on the average". There is a quantum physical probability to the motion of the Cooper pairs. I believe that when they move, they create a magnetic field. I am not sure about this but it seems right.

I do know that high temperature super conductors make noise that varies with temperature. LN2 isn't quite cold enough to make a high performance SQUID with them.

There's a way to make a volume with a very low DC field. Flatten a metal bag or one-end-closed tube, cool it to be superconductive, then expand it. The interior will have very little flux and it will be shielded from outside fields. Several of these can be nested.

John

Probably nitrogen oxides.

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
                                             (Stephen Leacock)