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For me it is usually a struggle to prototype a circuit to test/modify before I commit to building. Prototyping should allow easy construction and easy changes so for low parts count circuits with non-critical lead dress I use a “rats’ nest” method. This is where the components are soldered together with no supporting board or material. Here’s an example from my latest project on the bench:
http://postimage.org/image/e23i8wue5/
This circuit has 14 parts with an IC, which is not visible, clamped in the vise. It looks a mess but I built it in less than 1/2 hour and was able to test and make changes easily. This is a high voltage generator which I am going to use for a non Part 15 project. It generates an adjustable voltage from 600 to 950 volts drawing 0.5 mA from a 9 volt battery.
Some may not like this method but it works for me for simple circuits and I thought I would share it here.
Neil
Total posts : 45366You said the important thing, “It works for you.” It’s kind of a “virtuoso performance” that could only work for someone who had a good grasp of what the circuit was doing and a clear physical sense of where each part is hanging in open air near other parts.
I worked for an FM station that was strung together in a similar way, and they sounded great and were seldom off the air.
The photo shows art qualities.
I have hung circuit cards from old room sized computers right on the wall and it passed as art.
It doesn’t look at all like a high voltage circuit.
Total posts : 45366The “artistic” rats’ nest is one way to do it. Here’s another:
http://postimage.org/image/fv6ex8fkt/
This is the prototype for my “High Efficiency” AM transmitter oscillator and final. This took more effort since I made a cheap and dirty PC prototyping board. I hand painted dots and lines on a PC board and etched it to produce the proto substrate. The parts are top soldered on the board. This is better than the rat’s nest but it is difficult to use with ICs so the IC part of the board is rat’s nested. Changing parts is very easy with this approach.
Prototype boards similar to this can be purchased but I just made this from my junk box.
Early in my career I had a lab in a basement corner of an old hospital and my workbench was a 2×3 foot wood table. The whole place was a shared lab and very messy so the rat’s nest prototyping fit right in. My boss, a MD, once commented at a Board of Trustees’ meeting “Neil just throws parts on the table and stirs them with a soldering iron and out comes a working circuit!”. Some things never change.
Neil
Total posts : 45366Here are some photos of finished projects. These used a combination of wire wrap and “Vector Board flea clip” construction. These methods are a relatively easy way to produce one of a kind circuits.
A ham radio tone generator and tone decoder for a repeater control. Note the low frequency crystal in the glass tube.:
http://postimage.org/image/5awhenb31/Bottom view of a wire wrapped analog/digital board (the decoder shown at the bottom of previous pic):
http://postimage.org/image/98ochsna5/A FM stereo demux board I built in the late sixties before the nifty stereo ICs became available. The IC I used required large variable inductors and these appear to the left of the image. I used this in my EICO HFT-90 tube type tuner and this board was powered from the 6.3 VAC filament cirucit (rectifier and filter cap on the right).
http://postimage.org/image/d7lk0mbx9/Hope you enjoy the pics and maybe get some ideas to use.
Neil
Total posts : 45366Lots of various prototyping methods. So many that there is bound to be one or two that works comfortably for each individual.
Straw and rope, dead bug, desert blossom, junk yard, Manhattan, sprung spring, and the infamous wire wrap, just to name a few.
Personally I prefer the prototype board. Less mess, better organized and easy to change components without sacrificing its leads or committing to soldering and reclaiming.
RFB
Total posts : 45366Neil,
Your approach to building prototype circuits is exactly how i work. At first it is a major mess and i get comments like, “are you building a bomb?” “that wont burn the house down will it?” lolBut usually that mess turns into something very useful, and if it doesn’t you can just de-solder it all and start all over again.
I am chaos in motion anyways lol
Great post Neil.
Total posts : 45366The circuit exhibitions are enjoyed by this visitor.
The vector board with flea clips is what I used for Big Talker shortwave project.
I originally happened upon the vector board approach in the 1970s when building some mic preamps for a homemade audio mixing board used in my recording business.
My self-made circuits held up better than a lot of commercially made equipment. A Ramko Audio Board had circuit cards that everyday had to be jiggled or they’d lose contact. Cleaning didn’t help.
An ITC Reel-to-reel recorder was made with internal flat-ribbon connector cables that didn’t stand up to the current in some lines and many of the capacitors went bad in short time.
Here’s a question…. what kind of liquid hardener can be used to create sealed pot type encapsulated circuits that are made secret for all time? I tried it with some liquid glues but the impedances went crazy as the compounds must have contained conductive moisture.
Oh, and why is the crystal in the glass tube? Is it a virtual “oven”?
Total posts : 45366I finally completed the project that was shown “rats nested” in the first post. I thought there might be some interest in the construction technique I used for the final build. The construction used is called “Manhattan” or “Dead Bug” where the parts are mounted on a PC board and are self supported by their leads where possible. The ICs are mounted top side toward the board which gives it the name “Dead Bug”. One electronic advantage is that there is an excellent ground plane for fast signals and shielding. It may not appear to be so but component changes for last minute tweaks is fairly simple.
The circuit works as planned. The circuit is spread out a bit because there is 950 volts present and some high frequency hash from the HV supply was getting into the sensing circuit.
Anyone know what this is from the picture?
Here’s the link to the picture: http://postimage.org/image/5y9rxc6l9/
Neil
Total posts : 45366While having no clue as to what it does, I like it anyway and find it interesting to see. Thank you for posting it.
The black tube is a mystery, as it is probably not a florescent lamp, but perhaps a plasma generator, but I don’t know why you’d build one of those, so it must be something else. The large coil either implies VLF or an ultra-choke, but what’s the red round thing?
Maybe you are generating lightning?
Total posts : 45366Looks to me like a PWM circuit and booster to fire up a fluorescent lamp.
In other words…it looks like a home made ballast.
A new type of lie detector perhaps?
Home made “tuning eye” maybe?
Could be wrong though. 😀
RFB
Total posts : 45366I knew I could count on Carl for creative guesses. One of my other interests is radiation measurement techniques and this device is a Geiger Counter aka Radiation Survey Meter. The high voltage is necessary to operate the Geiger-Mueller tube which is the black cylindrical object in the foreground. The tube is sensitive to beta and gamma radiation and registers 12 counts per minute of background radiation. I have had the tube in stock for many years and just now got around to using it. It is a 1954 vintage surplus tube which was used in Civil Defense survey meters.
The red object Carl asked about is a 100 ohm potentiometer used to adjust the high voltage. Other items look mysterious because of the perspective of the photo such as the piezoelectric speaker (the black disc under the tube on the left) and one of the panel switches (the red and silver cube next to the speaker).
The unit is OK for general surveying but it lacks sensitivity for snooping for common radioactive sources around the house such as some antique glassware and pottery. It registers 650 CPM for a thoriated lantern mantel. In contrast, a scintillation detector I built registers 800 CPM background, 6,000 CPM for the mantel This is interesting because the mantel thorium is an alpha emitter and the scintillator is only sensitive to gamma radiation. The gamma is emitted by daughter products of radioactive decay in this source. I am in the process of making the scintillation detector portable and look forward to some interesting radiation snooping in the outdoor environment. The scintillation probe is immensely more sensitive than a Geiger counter and can be use to identify sources using a multichannel analyzer which is on my to build list.
I have had a sample of “Trinitite” which I obtained when I was a kid. Trinitite is the fused sand from the Trinity site which was produced by the first atomic bomb test in New Mexico. The Geiger counter detects the residual radioactivity of the atom bomb remaining in this sand and it is a bit unnerving to listen to the distant echo of the first atom bomb from over 66 years ago.
These instruments can be purchased but it is much more educational and interesting to design and build my own. Those who dabble with part15 homebrew stuff know what I mean by this.
Neil
Total posts : 45366Well that is interesting. Concerned about Fukashima’s leaking radiation getting your way or do you live near a nuke plant?
It is neat anyways.
So..what happens when you detect high radioactivity? Plan to warn DHS or NRC of your findings?
They probably wont care or do anything about it anyways. But its good to know for yourself if your living in a cesspool of radioactivity.
Just make sure your microwave oven and other Ghz devices are shut off or that thing will probably detect them too!
Trinity site a few miles north of my home town Alamogordo NM. I too have a sample of the sand stored inside a metal canister. It has the skull and bones emblem on the side! 😀
RFB
Total posts : 45366You posted while I was composing my oost so I didn’t see yours until I was finished. Yes, it does look a bit like a CFL or fluorescent lamp supply. The high voltage is generated by a flyback circuit which uses a choke coil instead of a transformer. I set it to give minimal voltage droop under load and it draws 4 mA from the battery. It can be changed to draw about 1 mA but at this current the HV is soft and caused problems when the tube was sensing high CPM. I finalized the design at 9V @ 4 mA in and 950V @ tenths of a microamp out.
Edit WHOOPS, we posted over each other again. Interesting additional comments from you. Other hobbyists report backgrounds similar to mine for both detectors so I have no reason to suspect anything out of the ordinary. Dangerous levels of radiation will saturate the Geiger counter so it is useless for atomic weapon fallout. An ionization radiometer would be needed. Since the Japan incident there has been a shortage of hobby grade detector parts. If folks are buying them to detect dangerous levels of radioactivity they are buying the wrong things.
Neil
Total posts : 45366Very interesting Neil! Have you considered writing an article about these and what people should look for in purchasing detectors or individual parts to construct one for their personal uses?
As you may know, the government in both the US and Japan are not exactly being completely upfront about Fukashima or even our own nuclear power plants. Having a detector around these days is a great idea and kin to having a smoke detector in your home.
Fantastic project Neil!
RFB
Total posts : 45366Having a radiation detector like having a smoke detector?
If there’s smoke you grab the extinguisher or call the fire department.
If there’s radiation what do you do, by a tent?
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