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John Wiltrout's Blog

145 posts
A week or so ago I wrote about my experience with a pair of Aven  10826F Flush Cutters   https://www.element14.com/community/groups/test-and-measurement/blog/2018/11/06/my-kingdom-for-a-good-pair-of-flush-cutters   I was very pleased with the response and the way the discussion carried over into the quality of small specialty pliers as well.   In the previous post dougw  mentioned having some good quality pliers capable of picking up 40 Ga wire. He asked how many pli ...
My latest experiments revolve around using the Chinese linear power supply board that has been the heart of many of my bench supply builds but rather than powering it with the tradition transformer and bridge arrangement I want to power it with a switch mode power supply.   Here is a schematic of the linear power supply board as supplied from the vendor:     My enthusiasm often gets ahead of my eyes and my brain so in typical form I assembled a board and left off the bridge di ...
I have been bugging a new friend, Neil, whom I was introduced to by genebren but whom I had never met face to face to let me know when his company would be attending an electronics show somewhere near my home. Neil is the founder and inspiration behind the company Tag-Connect out of San Fancisco. Neil has started a revolution in board connectors that simplify and economize on space and board cost without sacrificing connection integrity. Neil is also the person who is using his company and influ ...
I have had a Dual 601 turntable for many years, perhaps 50, and it used to work great. Sometime ago it started acting strange as the motor became unstable and would power up and lock on a higher RPM than proper. From the information on the internet it seemed that this was a design problem and would not be easily solved. I tried to fix it anyway. I tried external electronics to see if I could make it come up to the proper speed. I even messed with the pole spacing on the stater but the internet h ...
This is a second build of of a Simple DC Electronic Load project using information that I learned about curing Oscillations in a separate discussion: https://www.element14.com/community/thread/64985?start=15&tstart=0 The knowledge that I received from other element 14 members as well as things that I learned from the bad decisions that I made on the first build made me want to give it another try. Here is the blog from the first build: https://www.element14.com/community/people/jw0752/bl ...
Test Instrumentation Enter Your Electronics & Design Project for a chance to win a Grand Prize for Originality, a Tool Set, and a $100 Shopping Cart! Back to The Project14 homepage Project14 Home Monthly Themes Monthly Theme Poll   Thanks to continuing inspirations from so many of my fellow element 14 members I have launched into a project to build a simple DC Electronic Load. I built an Electronic Load once before on a larger scale as that one would handle up to 6 Amps at 35 VDC. ...
I have recently been helping my friend Judy organize and get her Electronics Parts store back on it's feet. This has meant I get to dig through the old stock and reorganize to my heart's content. As I was sorting packages of capacitors yesterday I came across some with and unexplained coil of what looked like solder. The coil was very tightly wound so that it had the appearance of a small spring 1 cm in length. They looked like this:   At first I thought this was a waste as no one would ...
About a year ago I decided that I would try to write an electronics related book. I had written, in the past, simple articles, a couple small books related to dental medical equipment, blog posts on this forum, and a manual for a desoledring station but never anything that would really qualify as a book. Unlike most of my friends on this forum I am not an engineer. I am a self taught technician so my first thought was, what could I possibly write about the would be of any interest to my engineer ...
Today I pulled an old telephone system out of a store that was no longer using it. The one thing that caught my eye was this Harmer Simmons RD 219 Power Supply. It is a beast of a linear power supply with +/- 24 Volts at 4 amps and 5 Volts at 7 Amps.     Weighing in at 11 kilograms it would probably make a pretty good boat anchor. Here are some internal pictures.         Based on the date codes on the chips this is mid 1980s technology and it was probably ...
For a couple weeks I had been on a roll with respect to leaving the basement door exit to the garage open. My shop is in the basement of my home and there are two ways to get into and out of it. The first way is a doorway and stairs from the kitchen area. The second way is a door and stairway up to the garage. It seems that I have gotten into the habit of going out the door leading to the garage with the intention to return immediately. The door itself has a school lock which automatically locks ...
Today I decided that for the fun of it I would smelt the jars of solder tailings that I have accumulated over the last 4 years. I have been very faithful in collecting the scraps and splatters as well as the solder collected from desoldering and salvaging circuit boards. Not only do I want to be environmentally conscious but I also want to avoid the damage that happens to the floors when solder and scraps of metal get embedded into the wheels of the shop chair.   I began the process by mak ...
Yesterday I was working to identify a group of SOT23 transistors that I had just salvaged from a circuit board. After crossing numbers and coming to a good guess of what the transistor was I used the analog meter to check the junctions. With this technique it is easy to confirm whether a transistor is an NPN or a PNP type. The non-slip probe tips make this testing much easier on the lose transistors as I can lock onto one leg and then probe the other two legs without slipping off my contact poin ...
Last night for the fun of it I disassembled a couple of circuit boards like this one:   I am not sure of their function but they seem to be a small receiver that is controlling 2 SPDT Relays whose switch contacts exit on the pins. I have about a dozen of them and the small project box and salvage components looked like a good collection of parts. After they were disassembled I began to ID the parts and among the regular things I found a 3 lead TO92 component marked 7039A-1. A little rese ...
This is a follow up on ntewinkel  blog of a week or so ago:   Nail Polish Short-proofing?   Since I use dollar store nail polish as a circuit sealer and insulator I decided to do some tests to confirm my assumptions that it is a good insulator. Fortunately my new inexpensive Megger arrived a couple days ago so I decided to learn how to use it and test the insulation properties of nail polish at the same time.   The plan was to put some solid wire on a piece of paper separ ...
This is a second chapter from my proto-book. I chose this article as it relates to a question the other day from nickgall2001 about designing circuits. While what I have done in this piece isn't exactly circuit design it is circuit modification and there are some parallels.     From Nothing to Something Adapting a Chinese Kit to a Useful Application               This is a kit from a Chinese source that was advertised as a te ...