John's Junk Drawer

Merry Christmas

2011-12-10T21:13:46Z

Our souls have value for one reason, and one reason only, because our creator values them.

http://www.youtube.com/watch?v=4Zh-yR0pbmU

"For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life."
- John 3:16

Merry Christmas everybody.

-djr

Update on the $80 Oscilloscope

2011-11-16T17:18:22Z

Finally got the intensity problem fixed on the new (used) scope. It was two bad diodes. I tried to get the original diodes, but that was not going to happen in any decent time frame.

. . . . . . .
The Fix.

Trusty ol' 1N4004 diodes don't have the fancy low-capacitance, high-switching-speed of the original diodes, but they have more than enough reverse voltage and power handling. . . Hmmm. . . would they work? YES! The scope is all calibrated now, and works like a charm. Now that the brightness works I can see what the whole Inten'D thing is for (my old Heathkit scope didn't have delayed triggering). Pretty cool!

. . . . . . .
Summary: $80 + a little elbow grease = 35 MHz Dual Trace Scope

The $80 price includes the shipping cost!

Model: JDR Instruments 3500

Found and downloaded a free manual (images scanned into a PDF). It was needed for the schematics to fix the intensity problem, but it also included the calibration procedures.

The guy who sold it was a bit of a sleaze bag (imo). He said, directly, that he wasn't aware of any problems, though he took a picture of it with the traces showing pulses. To me, that means he would have fiddled with the focus and intensity controls and seen that the intensity control had no effect.

So, it had a problem with the intensity that turned out to be two different diodes in the intensity circuit (go figure).

Now I've got a scope that probably cost >$1K new, and would cost $200-500 used in perfect working condition today. Not too shabby.

-djr

A New (well, for me) Oscilloscope for the Bench!

2011-10-27T19:31:10Z

The scope has arrived!

It came in the mail yesterday. A used, JDR Instruments, 35 MHz, dual trace scope for $80.00 (Shipping included) on eBay!

It had two obvious problems.

No horizontal positioning — I was able to fix that by following wires and traces back from the front panel.
The brightness is at full all the time — not able to fix that without schematics.

I spent a bit of time with it, and while it needs some calibration, I haven't been able to find anything else wrong. Also cool, it has a Z input in the back, which means I'll be able to play asteroids on it

-djr

Dennis Ritchie, Creator of the C programming language, dead at 70

2011-10-14T21:51:16Z

main()
{
    printf("goodbye, world\n");
}

Carrot cake - second attempt - a little better.

2011-10-13T18:14:00Z

The reviews are in.

2.5 large eggs are better than 3.

The instructions on the box call for three eggs and that's what the first try used. It seemed just a little bit too cakey and dry to me.

Reducing the amount of egg made it just a bit richer and moister, but not crazy-rich. Of course, I'm using jumbo sized eggs, which may make a difference. If you're using smaller sized eggs, three is probably going to be fine. whip them thoroughly first in the measuring cup before adding them into the mixing bowl with everything else.

Another Inch Out of the Ditch

2011-09-08T15:18:15Z

Finally managed to slosh enough junk around to clear the table in the foreground and then clean off the old workbench. The last time it was out from under a quarter inch of dust you needed a t-square to produce PCB layouts (see it there). The old scope smoked out as soon as I turned it on. It smelled up the whole basement.

All the bread-boarding sockets had been left completely uncovered under all the dust and in the dampness for the entire time. Nonetheless, I decided to assemble a small, experimental, logic circuit on the old breadboards and surprisingly, the circuit worked!

So, what does it mean if, while other guys are spending time and money building man-caves, you start building a maker cave? Well, you might just be a geek my friend.

Robot Arm Inventor and Pioneer Dies

2011-08-11T20:06:00Z

George Charles Devol
Inventor of Robot Arm

20 February 1912 — 11 August 2011

The self taught inventor of the robotic arm, which has become an icon of factory automation from Detroit to Asia, has died.

Story: Pioneer of the long arm of factory floor technology

Thankful for the things they've done.

2011-05-29T16:49:00Z

"Greater love hath no man than this, that a man lay down his life for his friends."
-John 15:13

Happy Memorial Day 2011

Today's Question: Bottom Up or Top Down?

2011-04-30T17:59:40Z

"I want plans by the many, not by the few."

Looks like it's getting some decent views.

Fix You in Blue(grass)

2011-04-26T20:01:00Z

A very nice bluegrass rendition of Coldplay's "Fix You".

He Is Risen !

2011-04-24T08:00:00Z

The greatest man in history, named Jesus,
   had no servants, yet they called Him Master.
   Had no degree, yet they called Him Teacher.
   Had no medicines, yet they called him Healer.
   He had no army, yet kings feared Him.
   He won no military battles, yet he conquered the world.

   He committed no crime, yet they... crucified Him.
   He was buried in a tomb, yet He lives today.

Happy Easter everybody!

Who's On First - Abbott and Costello - Phillies

2011-04-01T19:57:48Z

Alfred Russel Wallace

2011-03-25T18:33:23Z

"There is, I conceive, no contradiction in believing that mind is at once the cause of matter and of the development of individualised human minds through the agency of matter. "

— Alfred Russel Wallace

Kinetic Military Action. . .

2011-03-24T20:12:31Z

Looking for an answer to the question: What is a NON-Kinetic war?

Look no further. . .

From: White House: Libya Fight is Not War, It's 'Kinetic Military Action'

Define Kinetic:

Relating to the motion of material bodies and the forces associated therewith; "kinetic energy"

Does America owe George Orwell's estate some royalty payments for this?

In Memory

2011-03-23T17:27:11Z

Sometimes people get a lot of style, sometimes people get a lot of class. It is very rare for one person to get a lot of both.

Rest in peace Elizabeth.