Testing Chinese press-n-peel alternative (again)

With all these guitar pedals we've been making (as well as the PCB fails, wrongly-mirrored SMT designs and just outright failures) in recent weeks, our stock of press-n-peel blue paper has been hit severely.

The last lot we bought online was about £15 for five sheets - nearly three quid a sheet! Today, the cheapest we could find it on eBay was £21 + p&p. That's quite pricey.

Now we've tried alternatives to press-n-peel in the past, and found the old blue paper to give the best results. At least, it did when we used our big £2k-worth of Xerox printer. But that big old beast has gone to BuildBrighton, and the little desktop laser printer we have here at Nerd Towers is a hopeless Brother something-or-other.

Even on blue press-n-peel, the image is flaky, often there are broken traces and touching up with a Sharpie is now a common job. So we thought we'd give some of this cheaper transfer paper a try. The Xerox was great with press-n-peel, and so-so with cheaper, starch-based transfer papers.

But our Brother printer doesn't get the same crisp, sharp lines on blue paper - so perhaps it might actually work better with a different transfer paper? There was only one way to find out...

A quick click around on eBay and five days later, we had an impressive 100 sheets of transfer paper delivered for less than a tenner. That's less than 10p a sheet, compared to over £4 for press-n-peel blue. While that does sound cheap, it could still end up being quite pricey, if it doesn't work!

So what do the results look like?

Here's a "control". We're using the same method for creating these two boards, preparing the copper the same way we usually do, for both transfers, so that the only thing different should be the transfer paper. First up, our regular press-n-peel blue paper:

Straight out of the printer, the image is sharp and clear. Well defined tracks look like we should get a good image. But if you shine the paper towards the light, you can see that the toner has not been laid down as a continuous line of "ink" but appears to be "scaly" and looks like it could get put down in "layers" on the copper board.

The transfer has gone on ok. There are a couple of spots of black toner still left behind on the transfer paper, but most of the mottling is happening on the ground planes, and larger areas where it has been filled in. There are a couple of traces that were cracked, and a few with noticeable gaps in them that need touching up with a Sharpie.

Here's the etched board. Despite the slight raggedy edges where we've had to touch a few traces up with a Sharpie pen, it's not bad at all. There are a few marks in the larger planes, but the 0.3mm traces have all turned out quite well and the overall look of the board is one where the masked copper has remained pretty much intact.

Now with the cheap chinese alternative:

Out of the printer, the image already shows areas that could be affected by pitting - there are gaps in the larger areas and a few traces are already broken.

Compared to the press-n-peel image, there's none of the "scaly-ness" of the blue image - but you can already see that the quality of the yellow printing image isn't as good as the press-n-peel version.

The transfer process was very impressive. A few passes through the laminator, then about a minute in a cold water bath (just as we've been doing with blue press-n-peel for a while) and the entire image is transferred with no trouble at all. Not a grain of toner is left behind on the backing paper. The actual image transfer is far better than press-n-peel - it's just a shame that the printed image isn't as good to begin with!

After etching, the copper board does look a bit of a mess. You can see that the tracks are not particularly well-defined, but they are useable. Large planes appear "pitted" where the toner didn't transfer as a single solid block of colour, and appeared to have large "pin-holes" in the final layer.

After running a multi-meter/continuity test on all the tracks, they appear to at least work. But the overall finish of the board is a much poorer quality than the press-n-peel board.

So there you have it.
Cheap chinese toner transfer paper isn't as good as press-n-peel (at least, not using our scabby not-very-good-for-toner-transfer-Brother-laser-printer). It all goes to back up Steve's insistence that "you get what you pay for".

But at 10p a sheet compared to over £4 a sheet, and both give functional, working results, it's hard not to ignore the price difference. If only we could find a laser printer that would give a decent printed image on the yellow transfer paper, and things might be different!

Stompbox guitar tuner stolen idea

If you've ever seen a live band at the local pub (or bar) there's one song you've probably heard more than any other. It's an instrumental, and it goes "dum, dum, dum..... der, der, der...... der, der, ding, ding, ding, ding, ding".

Of course, it's the tune-up song, that just about every guitarist plays when they get up on stage. If you're lucky, you get to hear it once, at the start of the gig. If you're unlucky, they play it three or four songs in (and you've just endured the most atrocious fifteen minutes of out-of-tune string-twanging).

It's a pretty short song (if released as a 7" single, it'd probably have a run time of 0:21 or something) but it's tedious and noisy for everyone who has the misfortune to listen to it.

In a live environment, unplugging guitars from amps set to "moderately loud" can mean lots of popping, crackling and buzzing, as cables are removed, left lying around and generally abused. As a general rule of thumb, once you're plugged in and audible, it's best to try to stay plugged in (and use the guitar body volume to reduce any unwanted noise between songs).

Which means that plug-in tuners have lost out in the fashion stakes, for the cheap, vibration detecting, sit-on-the-headstock-and-detect-the-note-frequency type tuners - especially in a live environment. Which means, that as you tune your guitar, and watch the display at the end of the head, waiting for the note to appear in tune in the little window, everyone else has to listen to "twang, twang, twang" at performance volume; often as many as six times (each string needs to be plucked at least once, even if it's in tune, just to see that it is!)

A little while back, Tom - (the dude in all the videos from the previous stompbox workshop at BuildBrighton) - had an ingeniously simple idea. He took a cheap, plug-in tuner and turned it into a stompbox.

The point? Well, with the footswitch in the "default" position, it acts as a true bypass - simply sending the incoming signal to the output jack (and on to the amp). But when activated, not only can you direct the input signal to the onboard tuner input - you can also short the "output" signal to ground - ensuring that your audience hears nothing, while you're busy playing the open-string-tune-up song.

A plug-in guitar tuner costs about £3 on eBay, so it's no big expense, even it is goes wrong! We weren't not sure if our (cheap Chinese) guitar tuner was exactly the same as the one Tom had, so we had a quick look inside

This particular model had a mic (so it could pick up sound from an acoustic guitar, and be used for tuning non-electric instruments too) a battery compartment, an input jack and a circuit board.

Tom's design was so simple, we just had to rip it off - use it for our own project. He basically just clipped the heads off the LEDs on the circuit board, connected a couple of wires, and attached them to some LEDs that were mounted into the stompbox enclosure.

We ditched the microphone - we'll be taking the signal from the guitar out and it'll probably be a bit noisy for the tiny little mic to be reliable anyway. To make things easier, we soldered wires onto each of our LEDs before arranging them inside the stompbox enclosure. Then the hotglue gun came out and sneezed all over the place, inside the box.

It may look horrible inside, but once the box is done, it'll only need to be opened up once every now and again, to change the 2xAAA batteries that power the circuit board. By running the power lead from the batteries through one set of contacts on the footswitch, the batteries will be physically disconnected from the entire circuit when not in use.

A combination of poor drilling and sloppy application of hot glue means a couple of the LEDs don't sit perfectly true, but they're good enough for the effect we're after!

There's a tangled mess of wires by the time each of the nine LEDs has two (overly long) wires running to them, plus all the wiring between the circuit board and the push button. But eventually we crammed everything inside the little box.

(Before committing to screwing the base on the underside, we tested the pedal. Here you can see we're playing the G string - fnar, fnar - and our pedal is telling us that we're perfectly in tune)

The final pedal, ready for a nice sticker labelling the LEDs.

In our design, the top LED is always on, while the pedal is active (yes, we forget that since the top and bottom strings are both E we only actually needed five, not six, LEDs for the different strings, so found a purpose for this "extra" LED). Because power from the battery is also routed through the pedal, when it is off, the battery is physically disconnected from the rest of the circuit (rather than using the rather leaky soft-on button) so this should help reduce battery drain when the pedal is not in use. So, when the tuner is activated, we'll make this top LED light up (so you can see at a glance whether your guitar output is going to the amp or not).

The final pedal, with all the guts stuffed away inside.

Like our earlier fuzz face stompbox, this was a nice, easy, no-more-than-a-couple-of-hours project, but we've actually got something quite useful from it.

There's no real need for a full write-up and circuit diagram - it was more of a "hack" than a "build". All we've really done is just take existing LEDs, soldered on some wires, and connected up alternative LEDs on the face of the box. For anyone interested, here's how we wired up the footswitch.

Tuner Stompbox Pedal

The layout for drilling the stompbox enclosure is below.
(the drawing also includes the drilling layout for the earlier, as-yet-incomplete Fuzz Factory pedal, and some ideas for a sequencer wah pedal we're playing about with)

Pedal Drilling templates for stompbox

Fuzz Face guitar effects pedal

After putting our Fuzz Factory guitar pedal on hold - while we wait to get hold of some AC128 germanium PNP transistors - we were keen to make something - anything - that could make a noise.

It's often said that the Fuzz Factory is a Fuzz Face with knobs on. Quite literally.
So while we don't have the PNP transistors we need to complete our Fuzz Factory pedal, we do have some metal can BC109 transistors.

And these transistors are used in an alternative NPN, silicon-transistor based design. Here's a schematic based on one of the many designs available online:

Fuzz Face schematic by chris_holden2495

It's a basic twin-NPN design, and uses only a few discrete components (resistors and capacitors mainly, and a couple of potentiometers) so it didn't take long to throw together a PCB for it:

Fuzz Face PCB layout by chris_holden2495

This layout is press-n-peel ready - simply print and transfer onto copper board.
Here's the silkscreen layout, to position the components in the right places (from a top-down view, with the copper traces on the underside of the board)

The PCB has been designed to be not more than 24mm deep, allowing it to fit inside a stompbox enclosure at 90 degrees to the "face" of the box - meaning the potentiometers can be mounted directly onto the PCB (no nasty wires running about the place) but the orientation of the PCB means there's still plenty of room inside for plugs, sockets, pushbuttons and the all important battery.

(this photo showing PCB orientation is actually of the Fuzz Factory, not the simplified Fuzz Face, but demonstrates the principle of fitting a narrow PCB into the box at right-angles)

So while we've got a working effects pedal (see video below) it's going to have to wait a day or two before it can go into it's final housing. It turns out that being a ham-fisted oaf in the workshop can sometimes be a bit of a hindrance. Apparently a hole punch is for marking where to drill a hole in the metal box - not something you should actually punch a hole with! I'll have to lighten my touch on the next box....

Here's a video demonstrating the effect pedal in use:

(I couldn't decide whether to have the fuzz on green-for-go, or have the light green and go red when the fuzz was activated. In the end, I went with green=safe, red=danger - so the LED goes red when the fuzz is active. Look out!)

All in all, quite pleasing for an evening's work. Sorry the write-up's not much; pretty much because I just banged this one out, so I'd at least have one pedal I managed to make (and prove works) myself!

Dallas Fuzz Factory guitar pedal with AC128 germanium transistors

I've recently been learning how to play my guitar.
Not just banging out chords, as I've been doing for over twenty years now, but actually play the thing. With riffs and licks and the like. I got the Griff Hamlin Blues Guitar Unleashed course, and his Five More Easy Blues Solos lessons, and set about learning some guitar leads.

I've had the courses for about 8 months now, and still haven't got round to really spending any time with them -  I'm not much further on than I was when I first tenatively plucked out the opening notes of Ugly Kid Joe's "Everything About You" back in the early 90s.

Someone suggested going to a live jam session - not only to learn from others, but to put myself in a position where I have to learn something new or interesting, so I've something to "show off" on the night. So I attended a couple of Blues Jam Meetups and have played live with a band a couple of times now. At one point I even got in front of the mic and sang a little song

One thing I'm not mad about is bands where the guitarists "compete" over the course of the night, getting louder and louder. But there I was, on stage, with 12 bars to fill with some guitar noise. So I broke out my three guitar licks I knew and played them. And it sounded ok. But what I really needed was an extra little bit of oomph, just for the guitar solo - after that night, I decided that what I needed was a stompbox!

About a million years ago - ok, about two-and-a-half - at BuildBrighton we ran a build-your-own guitar stompbox effect workshop.

It was really well attended and everyone - eventually (some returning the following week) - went away with a working pedal. So we have a design which we know works. But one thing that's always been a bit of a bugbear is how it was constructed using perfboard.

Sure, that's great for the workshop, as it demonstrated the "hack-it-together-yourself" approach we wanted to get across, rather than just a "solder-this-existing-kit-we-made" type of workshop. But it always felt a little bit incomplete. But, just for this project, a PCB just felt right. So we set about designing one...

The schematic is a slightly modified version of the original one, with all of the controls brought out onto the front of the pedal

Fuzz Factory Schematic

This design includes pots for

• stability
• compression
• gate
• drive and
• volume

The PCB layout was designed so that the pots could be fixed straight to it, and that it would lie at 90 degrees to the "face" of the box, to reduce the amount of space that the actual circuit board took up, inside the box.

Amazingly, after soldering everything (ok, most things) up, it all still fit in the enclosure just right

Here's the final pedal, with all the plugs added, pushbutton fitted and all controls in place.

Maybe we could ask Steve to design us a funky new sticker for the top surface.

The only slight problem we have with this now is that is uses some old-school AC128 germanium PNP transistors - and we haven't got any here to actually test the pedal with! Perhaps Jason will turn up with a pocketful of them at tonight's BuildBrighton Open Evening?

SMT LED fail

While making some double-sided PCBs, we had quite a few left-over press-n-peel copies of our PCB design. It seemed a shame to waste them, but we didn't want to go through the trials of making more double-sided PCBs, so thought we could make single-sided versions of our sci-fi scenery walls.

Making single-sided PCBs is a doddle compared to double-sided (though quite why double-sided proved such a headache, we're still uncertain). It didn't take long to get a few boards etched and soldered up with some SMT LEDs.

For this particular design, we're using just a 74HC164 shift register to sink current through the LED to make it light up. Even without the shift register in place, we can test the board so far, by simply applying a low voltage (up to 3v) to the rails of the PCB.

So we did exactly that - applied 3v to the common power rail that is running to one side of every LED, and grounded the opposite sides of the LEDs, though the traces on the board. As each one lights up, we at least know that the LED has been properly soldered to the board, and that there are no breaks in any of the traces.

Except nothing lit up. Not a thing.

We checked our 2xAA batteries and they were working fine - the problem seemed to be with the PCB. Which, given it's only a few LEDs and some traces, seemed unlikely.

Reluctantly, we tried with the polarity reversed.
And every LED lit up, one at a time. Every LED had been mounted backwards!

Now the odd one might be forgivable - but to solder every single LED back to front it just plain crazy! We were quite diligent in checking the markings on the underside, to make sure that they were being soldered the right way around - but somehow, we'd managed to mis-read the markings on every one of the LEDs.
Then we came across this article online:
http://blog.screamingcircuits.com/2013/01/how-not-to-mark-a-diode.html

And it turns out that we're not the first ones to have had this problem. It turns out that some suppliers use the same markings to indicate different things!

In fact, sometimes the same manufacturer uses the same markings to indicate different polarities in the LEDs! So you can't always just assume that the markings on the underside of the LED will always indicate which way around they need to be mounted on the board.

In short, we're going to have to double-check every LED before placing it, to ensure it's the right way around. Our SMT LEDs have been dispensed into little multi-compartment boxes; we've no idea which are which, who made them, whether their markings indicate the anode or the cathode.... even a simple thing like an LED has suddenly just got a whole lot more complicated!

Double-sided PCB fails

It feels like ages since the Nerd Unit Laser Cutter was fired up, so we put that right this weekend. There are a number of projects on the go (as always) but it was good fun to fire up the laser and etch some boards, instead of messing about with laminators, press-n-peel, and the frustratingly awful Brother laser printer (the old Xerox was a joy to make PCBs with - this Brother laser printer makes every board a hit-and-miss affair).

Anyway, one thing we thought we'd try was some double-sided boards.
It seemed easy enough in principle - firstly, etch our PCB designs onto some MDF and drill out a few holes.

MDF?!
This is just going to be a template for etching; the idea is to place the copper boards on top of the template and when we hit "etch" again, it should carve the same pattern in exactly the same place on the board.

So after etching one side of our double-sided copper board,we drilled the same holes as we had done in our MDF template. Then simply push some pins (we used 0.8mm copper wire) through both the board and the MDF, to get the reverse side to line up

Tape the copper board to the template, spray with matt black paint, etch the reverse pattern, and.... ta-da!

Not exactly successful. The holes are probably a good 3mm away from where they should be!
Undeterred, we went back to the trusty old method of press-n-peel.
There are a few articles online about how to make double-sided boards with press-n-peel, and many use this same approach:

The idea is to print the design twice, one flipped (and mirrored if necessary) with a line exactly half way between the two designs. This is where we're going to crease the press-n-peel. To ensure that we got a perfect line up, we cut our press-n-peel along the very top of the design, and made sure that, after folding, the two top edges were perfectly aligned.

Insert the (double-sided) copper clad board, affix in place and laminate to secure the image

This time the alignment was better - but still not perfect (or, to be honest, not even good enough to be used!)

[photo here]

So in a last-ditch effort, we scrapped all the fancy-shmancy ways of making double-sided boards and went back to the method we know works best - etching just one side at a time.
This involves placing one design on one side of the board (using the "traditional" press-n-peel method) coating the reverse with paint (to protect the copper during the ferric chloride etching) and etching the board as if it were a single-sided PCB.

Then we drill a few alignment holes and clean the back of the board...

...and manually align a second design onto this reverse side.

Alignment is still not perfect - in hindsight, we should have image-transferred and etched the boards before cutting them down to their final size, so that the masking tape holding the press-n-peel in place had a bit more material to stick to!

Although not perfect, at least the alignment of the holes means this board will actually be useable. So the last thing to do is coat the front side (the bit that's already been etched) with paint (to protect it from the ferric chloride during the second etching) and to etching the reverse of the board.

And there we have it. A double-sided PCB that sort-of lines up.
Today's lesson - if you want to make something as quickly as possible, slow down, take your time, and don't try to do anything clever.

DIY guitar kits in Saltdean

My usual hardware store shopping list probably looks something like this:

• Jayes cleaning fluid? Check.
• Bin bag? Check
• Pan scourers? Check
• Multi-part DIY guitar kit? Check.

Ok, maybe that last one doesn't always make the list.
But that might change, after a recent discovery!

After helping a friend with his cooker hood, I called in at a little hardware store, on the main high street in Saltdean. Steve had already recommended calling in, just because of the bizarre combinations of things sold in there. So while I was in the area, I took the opportunity to see what he was on about.

And there they were - in the middle of a hardware store, among the tins of paint and rubber gloves and packets of wood screws, was a selection of DIY guitar kits!

Each kit comes complete with all the hardware for each particular guitar. So with the flying-V guitar, you get a Gibson-style fixed bridge and two humbuckers, with the Telecaster you get a maple-necked fretboard and two classic single-coiled pick-ups. The Warlock style guitar even comes with a Floyd-Rose style floating bridge, and locking nut!

Prices range from £140 to £160 - which when compared to a new instrument, isn't too bad at all. In some ways, these are even better than the cheaper-end guitars on the market, as each has a solid wood (mahogany) body (though the Les Paul copy has a striped maple veneer on top). That's far better quality than my first Squire Strat from over twenty years ago, which - even back then - had a plywood body!

Most of the range, other than the Telecaster, have rosewood fingerboards. I quite fancied trying a maple fingerboard again (my very first guitar had a shiny maple fingerboard, and every other guitar I've owned since then has been rosewood) but I really don't like the Telecaster shape (nor the slightly twangy sound from the rather basic electronics).

So what's the downside? Well, you've got to put it together yourself. You've got to put in the time and effort to get a decent finish. Some of the guitars on display were absolutely stunning - lacquered and sanded back and polished and lacquered and sanded back and polished about five or six times. And it showed. A couple looked like they'd been thrown together, just to complete the display!

So to get a really nice finish, you need to be prepared to put in a bit of work.
But other than that, these kits look like a really nice, relatively easy introduction to making and setting up your own guitar.

They're obviously coming out of China, but with modern CNC routing tools, there's no difference in build quality between these and the Fenders coming out of Korea, Mexico or even the US. Maybe the purists would balk at the idea of using anything but the most exclusive, expensive hardwoods, but for the price, these are pretty decent instruments.

The action on the few guitars I tried there was nice and low, without being "buzzy". The necks are nice and slim (my first Squire had a neck like half-a-drainpipe, it was so fat and round!) and easy to play on. The guitars were pretty much in tune, straight from lifting them off the shelf, despite just hanging in a hardware store for weeks at a time, so the machine heads and other hardware seems to be of decent quality.

 I haven't heard them through an amp, so have no idea what the electrics are like.
But the feel of the constructed demo models was pretty good.
Now I just need to rack up my brownie points, so I don't create World War Three when I come home with a new Flying V or Warlock in pieces in the next few weeks......

[edit: the website hasn't been updated for a while, but the kits are available online at http://diyguitarstore.co.uk ]