Thursday, January 28, 2016

Too much junk?


It's all good stuff. Not junk. No sir.

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Indoor and outdoor temperature sensors

Similar to my previous build, here are some more temperature sensors using DS18S20 TO-92 case 1-wire temperature sensors.

These are designed to talk to an AVTECH Room Alert system, but would work just as well with any device that can speak 1-wire protocol ( the ends are wired for AVTECH's particular setup. )

I chose the 'S' variant of the 1820 family because evidence suggested that AVTECH used the older devices. Besides, I'm not willing to plug an unknown device into a $1000 monitor without good reason!

Starting the build, I chose some scrap stainless tube, cut down to about 1.5" and cleaned of any flash or other sharp edges that may cut into the cable. A pre-made cap of rubbery plastic serves as the cap to the tube.

The sensors themselves are simply telephone-style cable soldered directly to the devices using "44" core flux, and then cleaned with alcohol. Heat shrink tubing was placed over the individual leads ( be sure to do that BEFORE soldering! ) with larger shrink placed over the whole assembly, leaving the sensor uncovered.

The sensor assembly is inserted into the tube, and the tube is filled with an epoxy. In this case I have access to some industrial materials from 3M, but any good, runny epoxy should do - as long as it's not corrosive to the leads of the sensor. The epoxy is allowed to cure, an RJ-11 is crimped on the other end, and that's it for indoor sensors. They are fairly liquid tight at this stage, but I like to go one more for outdoor use.

For outdoor sensors, I then dip the entire sensor end in tool dip, and allow that to cure. At this point, with the epoxy center and the rubberized overcoat, I'm fairly certain that these will withstand normal outdoor weather. I wouldn't dip it into liquid for extended periods of time, but it would probably work without issues.

Two sensors are now ready to go - one for indoor use and one for outdoor use.

It works! It's actually pretty nice today, for January!

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Some more Blonder-Tongue Audio Baton pictures

A family member recently gave me an envelope full of things related to my high school - certificates, grade cards, that sort of thing. Upon sorting out the papers, I came upon some more pictures of my Audio Baton restoration project. I'm not sure why these were in there ( and not in my private collection, ) other than I used their camera to take the shots. The negatives, however, are still missing...

The pictures, in order, show the restored underside of one of the chassis units, the rack case with the switching and meters ( Still like the way this turned out, the sweep on the front was pleasing to look at,) and the original cased unit. Sadly, the lettering was all scratched off for the bands, so I had to resort to a label maker. I had intentions of re-lettering them, but sold them before that happened.

The chassis itself doesn't look as nice as I remember - I guess time does make those things blurry. I do remember enjoying the rebuild process, and coming up with a tighter layout than BT's original setup.

( And yes, that's a copy of The Radiotron Designer's Handbook, 4th ed. in the bottom! )