HP Clock

Sunday, March 27, 2011

Artifacts found in the shop.

Much of the material that was moved out of the shop in haste is now being sorted.  No explanation is being offered for this image.....

Thursday, March 24, 2011

Shop is Operational

One of the final steps in making the shop operational was the replacement of the original 1961 bench tops with new maple bench tops.  The original bench tops were made from discarded wood.  In this picture the walls of the shop see daylight for the first time since the shop was built.

Next, it was necessary to construct new level bases for the maple tops.  All of the support lumber was four by four redwood, making for a sturdy base.

Here is the completed results.  One bench is at a sitting height while the second bench works well when standing.  In the second photo you can see the original front door that I saved from the house when it was demolished.

Monday, March 7, 2011

Motorola Mystery

While trying to restore an older analog bench supply I discovered that the series pass transistor in all of the regulating circuits used a Motorola 1700G transistor.  The mystery is I can find no record of this device either on the Internet, or in the large collection of Motorola data books that I have.  The part is clearly marked with the famous Motorola logo and the number 1700G.  I’ve even gone so far as to dig through boxes of used books at OpAmp Labs Book Store. (http://opamp.com) By the way one of the best technical book stores in Los Angeles.

I was able to get a sense of what the device was from looking at the schematic and putting it on my Tek 575 curve tracer.  ( fixed up discard from a friend who found it at a ham-fest in Santa Barbara.)  Here is plot from the curve tracer that I labeled using Photoshop.

One of the handiest pieces of hardware that I have, other than the curve tracer, is an old scope camera that I modified by removing all of the Polaroid dependent parts from and replacing it with a shelf and baffle that accommodates a small digital camera. 

Here is a picture of the camera in use on a Tek 556 dual beam scope.

The good news is that all the series pass transistors appear to be good.  I am, however, still surprised that I can find no record of this device.  If anyone knows anything about this mystery device, let me know.