Friday, April 8, 2016

Scribble Style - Quick and easy layouts on copper clad

Greetings Hombres*

 Today I would like to share with you how I have been making my RF PCBs lately. In my previous blog posts I documented several different methods of making PCBs but Scribble Style is so incredibly quick and effective that I can't imagine ever going back.

While browsing around the hardware section at the new Menards store that opened up in my town, I found a cheap $5 tool called a Scribe. It is a small metal hand tool with a very sharp carbide tip. I thought that it would come in handy on the bench but never imagined it would work so incredibly well for making PCBs. The carbide tip is replaceable for if it dulls but I have used it hundreds of times on many dozen boards and have never had to replace it or sharpen it.

"Scribble Style" is quick and easy. It doesn't take much force at all to remove copper of various thicknesses off of the board. You don't have to fuss with superglue or dremel tools. No more breathing in fiberglass dust or staining your clothes with ferric chloride. You simply scratch the board and you have your layout! A single pass on the PCB is sufficient to create a pad or track that is isolated from the ground plane. If you are doing vhf or uhf work, it is very easy to simply use a ruler and an indelible ink marker to make your layout for 50-ohm microstrip lines and then scribble the copper right off.

My dear XYL came up with the term "Scribble Style" as it involves using a Scribe and I just scribble the layout onto the copper clad as I go along from stage to stage. Of course you can plan out a beautiful perfect layout before hand with this technique too - the beauty is that the Scribe, a $5 tool, does a better job than any other tool I've made or technique I've tried. It pairs well with ugly style too.

I have taken some photographs to help illustrate the technique. I hope that you get your hands on a scribe and try making your next homebrew project this way.

Here is the magic wand that does it all. A $5 Scribe. This isn't the exact one I have but it looks quite similar. If you don't have a Menards near your QTH, you should be able to purchase one from Amazon or Ebay. Spend the $5, get a scribe and start scribbl'in today!

It only takes a few seconds to make each track or pad.

If you're not sure of how to lay the circuit out, just put the part down on the copper clad and start Scribblin'!
You can do the entire circuit board this way, just progressively add parts, arrange and rearrange, Scribble and then solder.

 It is truly the quickest and easiest way to make a circuit board that I've ever tried.

 A few more Scribbles later & it's done.

I had to make several changes to the above circuit but it was very easy to do. This method lends itself well to experimentation and rapid prototyping.  The above circuit is a 100-kHz Frequency Standard/Marker. I tried several different designs from the books but ended up designing my own from "scratch". ;)

 Here is a Scribble Square. It took all but 10 seconds to make. Why etch? Why Dremel? Why Glue? Just Scribble scratch and solder! Et Voila! You're Done! :)

                                                        Don't forget to check continuity

The following is the 100-kHz oscillator I ended up designing from Scratch. It's just a Colpitts oscillator. I added an amplifier and some germanium diodes to generate harmonics last night but didn't snag any pictures of the additions. The feedback caps are 3.3nF.

 After making your Scribble scratch, sand (or use another method) to clean up the copper debris.
 If you do get a short, it's likely not because it didn't scratch deep enough but rather the culprit is usually a small flake of copper debris bridging the scratch.

Notice the debris left around the edges of the scratch.

           Give it a nice gentle sanding to clean it up.

     Now that's better!

The following three images may best illustrate how very simple it is to do this.

Well, there you have it, friends. I'm sure that I'm not the first one to use a scribe for making PCB's but I am glad to finally have made a post to share it with all of you. It really is so much simpler and cheaper than any of the other methods I've tried.

Please let me know in the comments below if you give it a try or if you have already been doing this for years. I'de love to hear from anyone who tries this or makes any adaptations to the method. The more we share the more we grow as a community.

Now get to building something and have a wonderful time doing so!

73 - KE0BFF

* - Hombre = HOMeBREwer.

Monday, September 14, 2015

Simple tools for winding toroids.

One of the more intimidating challenges to fledgling homebrewers can be the dreaded toroid coil.  When I first started building I would often try to avoid  circuits that required me to wind coils. This didn't leave many options in the way of radio frequency circuits. I first got my feet wet with simple air wound coils used in projects like single transistor FM band transmitters & similar projects. The time came when I knew I had to start winding coils around toroids. In this post I am going to share a couple simple tools that I use to get the job done.

Most of the projects will tell you how many turns to make around the core. Certainly one can just make the specified number of turns around the coil and hope that it is the right inductance needed. Most projects recommend compressing or expanding the turns while monitoring the output on a scope or power meter. That works fine too. However, if you want to be able to actually measure and control the coil inductance than you need to have an accurate way of measuring it. There are a few options out there, including some DIY analog & microcontroller based L/C meters. I took the advice of my digital elmers and went for the Almost All Digital Electronics L/C Meter IIB . I had to save up for a bit to get it but it was a very smart investment and I recommend it to the RF curious. It's a powerful tool that I use nearly every time I build a radio frequency circuit. It allows one to measure the value of capacitors & inductors of the small values used in such designs. One use for it that I like is to see how a particular component's value reacts to temperature changes. A quick blast of freeze spray to test an NP0 versus an X7R capacitor or a coil wound on a type 6 or 7 mix versus one wound on ferrite core. It's fun and has given me a better understanding of how well different component types hold up to fluctuating temperatures.Even if you don't decide to obtain an AADE L/C you can absolutely still use the so called 'cut and try' methodology by compressing/expanding while monitoring the output of the stage. Whatever methods you may use, I hope the following is helpful .

Here are some of the tools that I use to make winding toroid coils a bit easier. Please know that I claim no originality or blame for the effeciency of these 'tools' . I offer my most sincere and humble respect to the many homebrewers that came before me and shared their experiences and wisdom by publishing it online or in zines like sprat, hotiron, AmQRP homebrewer, QRPQuarterly, etc. There are so many amazing builders that have inspired me with their articles, webpages & other contributions to homebrewing that I hope to dedicate a post in the future in celebration of their accomplishments. Now, let us learn of these simple techniques.

The tool that I find most helpful for winding coils is a simple "Chop Stick", the utensil commonly used to eat Asian cuisine. These are incredibly easy to acquire. They often come attached at one end and are then split apart into two separate chopsticks. Each stick being tapered at one end. Using a vise (You can get creative here if you don't own a vise) to hold the chopstick, the toroid core is slipped over it and allowed to rest. I added a ring of tape to stop the coil from sliding further than about 2/3rds the way down.

Slide the core up just enough to feed the magnet wire through, observing proper phase, and then pull straight down making sure it's taut. Note that care may be needed to make certain the magnet wire's enamel doesn't get scraped off in this process. Some have coatings that flake off easier than others. I then push the core back down, gently, just to sort of press the wire as firm & flat as possible against the core. Next, sliding the toroid core up again just barely, feed the wire back up through the center of the core and pull gentle but tight straight up. You now have two passes or turns through the toroid. I usually push the windings right next to each other and try to make it as flat, firm & tight as possible without scratching the enamel off or breaking the wire (especially the finer gauge stuff).  Do this repeatedly for the required number of turns.

Moving on now to the next tool, which is a really simple one I came up with that I gave the silly name of ''The Denameler' because it De-Enamels the magnet wire. It is simply a metal fingernail file, "borrowed" from my xyl, broken in half  and then affixed to itself to create a simple & quick way of scraping the enamel off the magnet wire. I think the picture will do more justice than my words will.

After "De-namalling" it (i know this is not a correct use of the "de-" prefix, it's just silly) we need to measure the inductance with our trusty AADE L/C Meter IIB. Compress/Expand the windings until the desired inductance is reached.

Next on the list is poor man's "Q-Dope". Some folks use real Q-Dope, I never have, and others make their own by dissolving packing peanuts in acetone. I just "borrowed" another item from the XYL. It is called "Hard-As-Nails" with Nylon & Retinol. I coat my coils with a thin layer of it and it holds the windings firmly in place. If you wish, you can leave a small portion of the windings uncoated so that you can make minor adjustments by expanding/compression them in the future. Let it sit until dry and you have yourself a very well made coil. I am curious if anyone else has used this or similar type items to seal their windings. Please share.

When first starting out, it helps to be able to order just one or two of each type. Earl, in Canada,  runs and sells small quantities of toroids to homebrewers.

There are lots of great tools, wares & tips available to help make homebrewing easier and possible for everyone. It's important to try all that you can, find what works for you and develop your own system or routine for the process of designing, building & measuring rf circuits. Please be sure to share your helpful tips with others because it is the contributions of the community that keeps homebrewing alive.

 If you can't find the right tool for the job, you can always make one. It doesn't matter how simple or ugly it is, if it makes the job easier or better.


Sunday, September 13, 2015

An RF Mandala

I thought I would add a beautiful shot of a naked SRF3864 so you would have something to meditate on while I proof read my coming posts.

Monday, August 24, 2015

The Hombre's Return - Handy Homebrew RF Resources, Permission to Fail & Errata

Greetings to all. Please excuse my hiatus from updating this blog. I assure you that it was not from a lack of productivity. I have been busy building, studying & experimenting with all aspects of my autodidactic pursuit of RF wisdom. I have SO many projects and builds that I am eager to share with you but there will be plenty of time to "show off" my projects in the future.

Many of my projects fail to work or meet my goals in some way. Sometimes it is an issue of poor planning, incorrect assumptions, wrong measurements or even over ambition. Many of the times it is the inability to create the circuit/system in the form factor that I envisioned.

One of my recent projects was Roy LeWallen's Optimized QRP Transceiver. I worked on this project over the course of three months. Most of that time was spent drafting the layout on graph paper. I will share this story, including photo's, design/layout tips and a humble true confession of why the project failed in the end, in a planned future blog post titled: "QRP My Problem Child". For now I am simply giving that experience as an example of a very frustrating failure to turn a homebrewed transceiver into a user friendly radio. The problem was the inability to create a proper enclosure for it. Steven, KC2SIZ, created a post on the QRZ > Homebrew forum called 'The Homebrewer's Lament' that I recommend you check it. He shares his thoughts and frustrations that I believe many of you will relate to.

The topic of failure is important. If we don't give ourselves permission to fail then we are denying ourselves the right to learn. Experimentation is all about failure! I wish to encourage everyone who is interested in building circuits of any kind, whether you have years of experience or none at all, to watch this incredible video by Jeri Ellsworth: Secret to Learning Electronics - Fail and Fail Often

In this informal post I also wanted to share a few tips for resources that I have found helpful. Whether you are recalculating the component values to change the band of a published transceiver design, designing your own circuit from the ground up or needing to do quick math on the bench to determine how much parallel capacitance you need to bandspread your VFO, a calculator is a wonderful tool. There are a number of great online calculators and free programs to help us solve design problems but sometimes it's nice to have one on hand, in pocket or on the bench.

 While in fact any dollar store calculator will work just fine, I wanted to find one that was a little more specific to my needs (I should mentioned that if it wasn't for my father offering to purchase it for me, I would most certainly have taken the route of the skint hombre & got the $1 shop calculator). I started my search by digging through posts on the EEVBlog Forum to see what the real engineers were recommending. What I discovered was dozens of pages of discource debating the merits & faults of various brands, models & systems. There seemed to be as many different types of calculators as there are branches of engineering! I started tallying up the recommendations for each particular model. I then narrowed it down to the ones that were in my price range & being sold as new online. Many of the suggested models where vintage and extremely expensive or unobtainable used. I decided on the Casio FX-991MS Plus.

The Casio FX-991MS Plus has the feature of being able to use the engineering notation for pico, micro, nano, Kilo, Mega, etc. so it makes solving circuit problems much easier than other calculators that require you to count the zero's or use other forms of notation. I highly recommend it. In a later update to this post I will cover some of the keystrokes & features of this calculator as well as give some examples of how to solve some of the equations we use when working with RF circuits. So please check back in the near future.

Thanks go out to Chris Gammell (of TheAmpHour, ContextualElectronics & and to Pops aka Todd aka VE7BPO ( for their neighborliness and encouragement for me to continue developing this blog despite the lack of visitors. Thanks guys.

That is all for now.  This was just meant to be a quick informal post but I plan on creating many more in the coming weeks so please check back for more homebrewing tips, circuits, project photos, tutorials & ramblings of an RF Hombre.

73, -.-    .    -----    -...    ..-.    ..-.

Saturday, March 21, 2015

Homebrew Layout Methods & Tips


I have been experimenting with different ways of designing the layout for my RF homebrew circuits over the past few weeks. We all know of the common methods like etching a board with ferric chloride, dead bug, ugly style, tag strips, veroboards, strip boards, & Manhattan style. I've even made a post on how I make my island pads. Innovative homebrewers have been developing and sharing these methods for decades.

Circuit Layout on Foam
One method I read about described using a sort of styrofoam as a base. A piece of paper is laid on top and the components are pressed into the foam just like they would be laid out on the circuit. Then the traces are drawn and this drawing is used as the template for the board. I decided to experiment with this method but with a twist.

Toy Projector used in layout experiment

 I used this old toy projector that I acquired at a thrift store many years ago, to project the layout directly onto the copper clad.

Projecting the layout onto the copper clad
I then traced the layout onto the board and finally used a dremel with a cutting disc to cut the design into the board.

Safety glasses & a respiratory are mandatory when cutting copper clad!

Although this method kind of worked, it was a bit of a hassle and didn't turn out as well as I would have liked.

Result of first layout method experiment.

Many homebrewers before my time extol the many uses of Blu-Tack, also known as Sticky Tack.

'Hombe' Putty Par Excellence

This is that putty like material that you use in place of thumbtacks to fix a poster to a wall. It can be purchased at just about any department or general store. It was when I was deciding how to build a 40-Meter version of W1FB's Universal VFO from his book, 'W1FB Design Notebook' that I stumbled upon two new uses for Sticky Tack. I am hesitant to say these uses are new, because everything I know about homebrew RF design comes from the grace of those who came before me and openly shared information. However, these two uses are new to me and I hope that they will be new and useful to you as well.

Some authors suggest boiling your toroids after winding them as a way to "anneal" them. Others suggest using Q-dope. I usually use Elmer's wood glue but now I will be using Sticky Tack.from now on. Simply wind your coil around the form. Using your AADE L/C meter (Absolutely essential to successful homebrewing), compress or expand the windings of your coil until the desired inductance is reached. Now place a layer of Sticky Tack on both sides of the coil and join them together around the outside & inside of the coil. Double check that the inductance is correct again and fix it to the desired place on your board. This seems to make the coil quite mechanically stable.

Now on to the second use of Sticky Tack.This was the second layout method experiment that I did. I was much more pleased with the ease of this method and the results in comparison with the projection method.

I start by placing the components on the board by sticking their leads into the putty (StickyTack). Note the coil wrapped in putty to the left side, below the off board variable capacitor.

Ignore the different coil used, not mechanically stabilized in putty, during these layout images. 

 Using a hand tool that allows me to bend component leads at an angle, I found the best way to place the components into the putty is to slant them down at an angle sharper than what is shown in the image above.

 Components leads that are to be connected to the ground plane are not placed in putty, Using this method of layout lets you try all sorts of arrangements with great ease.

 Once you have determined the best arrangement of the layout, remove all the components and straighten the edges of the putty, I used another small handtool for this but a flat head screw driver or something similar would work.
No that's not chewing gum and those aren't bite marks. Thats Sticky Tack, putty, and the edges are like that from the small tool I used to straighten out each isolated "putty pad".

 Once all of your "Putty Pads" are straightened out, use an indelible marker (Sharpie) with a fine tip to trace around each pad.

 Remove the putty, and you have your layout. It's still a little less than perfect, but all my circuits are ugly, so I'm fine with that.

 I went over the layout one more time with the marker, to make the lines darker and well defined for the next step.

I like to use a lower power rotary tool for cutting islands & pads. a dremel with only one speed is a bit overkill for this. i use a cutting disc. It only takes a few minutes and the results are great. Use safety glasses and a respiratory! Do it outside and make sure other people or animals will not be able to breath in the resulting dust. It is very dangerous.

 Once the cuts are made use your favorite abrasive to clean up the board. I prefer the wet/dry sandpaper sponge on the upper right.

She's a beaut!  Cleans up awfully nice doesn't she? Note that the solder already on the board is there because I am reusing this piece of copper clad from an earlier experiment. It is single sided, as it is being used for a VFO.

As always, check for continuity using a multimeter. Make sure all the pads are isolated from each other and ground. If any shorts exist, fix it with a utility knife. (safety glasses!)


 I hope that the above information and images explained this layout method experiment well enough to comprehend.  Below are pictures of the build process for the VFO for your enjoyment. It turned out really nicely. :)

So there you have it. I sure would love to hear some feedback. Maybe you have been using this method of layout for a long time. If so, please speak up so we can share suggestions! What uses for Sticky Tack do you find helpful in the RF homebuilding lab?

Thank you for your time. As always, keep your iron hot and stay fluxy!