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John Wiltrout's Blog

180 posts
  This is the main circuit board from a Dental Clinic Sterilizer. It is a very popular brand that has been sold extensively across the USA as well as internationally. One of the power outputs of the board is controlled by a 30 amp relay that powers the main heating element which draws upwards of 12 Amps. The circuit is fused by a 15 Amp fuse (See the white ceramic fuse in the middle of the picture). The circuit board mounted fuse clips are rated at 20 Amps. This would all seem to be well e ...
Recently I have been having a hard time watching my television. There are a lot of people on the TV lately who like to make up things and tell lies or at least bend the truth around so that one can not tell which end of the horse to kiss. These alternate facts as they have come to be called usually get me up out of my chair, hollering as loud as I can with my fractured voice, and explaining to my wife who usually isn't paying attention to me or the TV, what the latest conspiracy theory is. I hav ...
For about a year I have owned a Hantek 8060 dual channel oscilloscope. I have been very pleased with the scope as it is well suited to my needs. I use it in my simple experiments and I use it for helping me diagnose equipment that is in need of repair.   About three weeks ago I was working on a Denstply Cavitron which is a device used in dental clinics to clean scale from teeth. The Cavitron produces a 30 kHz vibration in a metal tip that quickly removes plaque and scale from teeth. The de ...
Recently my scope and I had an unfortunate encounter with some high voltage and it left me with one channel out. I am slowly working through the process to see if I can fix the scope. I will blog about my journey at a later date whether I can fix it or not. Among the damage the high voltage caused was the loss of the 1X circuit in the probe cord set.     This is an inexpensive 80 MHz Hantek probe and after the high voltage experience the 1X  10X switch had no effect. My first t ...
jw0752

A Do Nothing Machine

Posted by jw0752 Top Member Jun 20, 2020
The Thinker Revisited             The Thinker Revisited is an Electronic Sculpture built on an X-Ray Control circuit board. I usually salvage these boards for the parts but since I had already taken a couple of identical boards apart I decided to have some fun and see what would happen if I began to add electronic systems and some little electronic kits to it.               The system ...
jw0752

World Tour

Posted by jw0752 Top Member Jun 12, 2020
I got the idea for this Blog from jancumps . Since the Covid 19 has kept us from getting out and traveling I thought it might be fun to give you a short tour of my home town Chippewa Falls Wisconsin USA and to invite you to add your own tour of your home town in the comments. I am suggesting that we make it a short tour with six pictures or less. If you can highlight an industry that relates to electronics all the better. Background information and history is always appreciated.   Very c ...
I am busy salvaging circuit boards while my mind resets and a new idea for a build takes form. Yesterday I disassembled a circuit board from a Planmeca X-Ray machine (a company from Finland) that dated from the 1990s. Among the salvaged components were a few that looked like this:        I have seen something similar in other equipment that was packaged in brown ceramic but this is the first time I have come across this style. I believe I even knew the name of this type of ...
I am very lucky to have a son in the Dental Equipment Service Business who faithfully watches for circuit boards that he can salvage from discarded equipment and deliver to the old man (me). Here is the cache that I got on Friday.     Sometimes I will just salvage them out for the parts but I am always watching for interesting assemblies that I can add to my resources and repurpose. Among the boards were 2 sets of (11) lighted momentary push button switches. These switch banks came ...
Today I am working on a circuit board from a Dental Statim Sterilizer. This sterilizer is unique in that it doesn't work by heating water inside the sterilization chamber but rather it has a separate boiler. Water is injected into the boiler and then the steam and pressure that is produced goes into a sealed tray, called a cassette, that contains the instruments to be sterilized. The advantage is the it is a very fast process and can potentially sterilize instruments in a fraction of the time ne ...
jw0752

AC Optocoupler LTV 814

Posted by jw0752 Top Member Feb 22, 2020
When I used to repair dental chairs it was very common to find a logic circuit communicating with a line voltage triac through an opto-coupler. The chair's actuators were typically 115 Volt AC motors. These opto couplers had an internal LED tied to a light sensitive semiconductor junction that would, when illuminated, fire the triac and allow AC line power to flow to the motor. Until a couple days ago, however, I didn't realize that opto couplers existed that would allow AC line voltage as an in ...
I like to think of the parts and pieces in my shop as building blocks. I very seldom design my creations from the ground up. Like the Borg, I prefer to assimilate technology. Once I have a board or circuit that I find a useful building block I go to work on it and modify it and twist it to my purposes. One of the circuits with which I have had the most fun is a power supply module that was marketed as Hiland Power Supply Module. I do not know who was the original designer. The design has been ta ...
  A while back I bought 8 of these small 0 to 30 Volt 0 to 10 Amp panel meters from China. I like to use them in my builds because they have in the past worked well for my needs and they are very inexpensive. The other day when I needed one for a new project I found the 4 of the 8 would not zero on the Amp Scale. They would say 2, 3, or 4 in the least significant position and this number would add to the actual current that the meter was attempting to read. This put the meter outside the s ...
In early November ralphjy told us that his NVR had died. In the course of the discussion and Ralph's experiments it was speculated that there was a short on the board that was pulling down the power supply. Over the years as I have serviced equipment this has always been a challenge to find the point or component that is the source of a short on a circuit board. In the past I have followed traces and cut them as needed to step by step find my way to the source of the problem. I have often though ...
If you have followed my blogs you may know that I like to walk at night. During the summer months I always have a small flashlight in my pocket or in my hand. Since I dress in black or dark colors and I am sometimes in the roadway, the flashlight allows me to alert drivers of my presence. It is also useful if my pathway is particularly dark or hazardous. I have previously made a boot light  https://www.element14.com/community/people/jw0752/blog/2019/08/01/walking-in-the-dark which has grea ...
In January of 2009 my wife Millie and I were the owner operators of a small Dental Equipment service business. We operated out of our home town and drove 100 miles in any direction to the dental clinics of our customers to repair their chairs, lights, drills, x-ray units, and any other equipment in the clinics. It was a niche business and by providing 24 - 7 service to our clients for the previous 20 years we had come to be the dominate repair service in our area. My wife Millie, a dentist herse ...