sexta-feira, 28 de Março de 2014

quarta-feira, 26 de Março de 2014

Fixing a BOSS FW3 wah pedal

Just the other day I found a BOSS FW3 wah wah on an auction site and got it for 40€. Although the previous owner stated it was in “mint condition” it was somewhat far from it. The slider pot (yes, this wah has a slider pot instead of a rotary one) had been messed with, removed and placed back again with hot melt glue. Fortunately is it working fine and I’ll worry about it when the need comes. Some of the screws holding the base plate were also missing and the pedal was soaked in oil , grease an fuzz…

The pedal was in good working order though, the seller even threw in a brand new Duracell 9V block, and the only real problem was what led me to write this post:

-          An annoying malfunction with the indicator LED was making it unable to keep lit when the effect was engaged. Instead it flickered or remained off…

This really upset me since the indicator is in my opinion a major feature on a pedal that more established brands (when it comes to wah wah pedals) incomprehensibly opt to rule out of their designs… The BOSS FW3 is also built like a castle and, even if it didn’t work at all, 40€ would be a fair price for the case alone as a DIY start point…The wah circuit was working fine though…

Anyway, I set myself to give the thing an overhaul.

I’ll refrain from posting pictures and details of the cleaning process since there’s really not much to it: Cleaned the PCBs with Isopropyl, completely disassembled the case and pedal and degreased it with hot water and soap,  LIGHTLY lubricated the shaft with car motor oil and that was it. Now, for the LED:

After a quick look at the small PCB where the LED is placed I found a Zener diode in series with the LED and somehow got suspicious about that fellow:

 I went on to search the web for reports about the same problem and, although I found none, I managed to find the circuit schematic here:

Here's the important part for this case:

I suppose BOSS designers put the Zener there so the LED could double both as a status indicator for the effect AND as a battery charge indicator. I’ll try to explain:
Zener diodes act upon electrical flow the same way spring loaded valves act upon water: They only let the flow through if a preset pressure (voltage) builds up upstream of them. So, as the Zener only lets electricity pass through it if the voltage rises above its preset point, the LED will only light up if the battery is able to provide a certain voltage. This way BOSS ensures that the user is made aware that the battery is getting low on charge but the pedal keeps on running for a while because the Zener diode is only in series with the LED. Think of this system as the reserve light on your car’s fuel gauge:
When it lights up you’re still good to go, but you have been warned that it won’t last much longer.

As this, if this Zener is malfunctioning it will affect the indicator LED:

-          If the Zener is shorted the “warning” effect is lost and the LED will keep lit for far longer into the end of the battery’s life
-          If the Zener is open (or if its Zener voltage is somehow out of spec) the LED will not light up at all or will show an erratic behaviour

One good way to check if a Zener diode is doing what it is supposed to do (in simple regulator circuits such as these) is to measure the voltage between a point immediately downstream of it and ground and between a point immediately upstream of it and ground. If the voltage upstream equals the voltage downstream the Zener is shorted. If the voltage downstream is 0 the Zener is open.
In my case the downstream voltage read 1.3V so, although not completely open, the Zener obviously was not letting enough juice through to power the LED.

Since this pedal is to be kept in a pedal board powered by an external supply and there’s no need for low battery warnings, I simply put a jumper across the LED to solve the problem:

Now the pedal works perfectly and the LED lights up and shuts down as it is supposed to:

If a more “professional” solution was desired I could have simply replaced the Zener by a new one (any 5.6V Zener would do) and the pedal would have been restored to its original condition.

This fix should be OK for all pedals that use similar circuitry.


Pedro , from Portugal.

sábado, 4 de Janeiro de 2014

A new chipamp project part II- A simple DIY guitar power amplifier

 ...for use with an external speaker and some sort of line level preamp (for example, a Behringer VAMP3)

still on a very initial stage (little more that the marine ply box done)

sexta-feira, 29 de Novembro de 2013

A new chipamp project

With the new family member almost here it was time to confine the prototype to a box:


It's just a straightforward application of TI's datasheet circuit:

Still to do:

- An impedance matching buffer for the CD/MP3 input:

- Incorporate the RIAA preamp in the box:

- Improve the volume control

- Make an output attenuator

domingo, 20 de Outubro de 2013

Regata Belém Alhandra Belém 2013

Mais uma vez a velejar com rating 0.000..., o que é uma pena, lá viemos rio acima... Desta feita eu e o Paulo Garrafão.

domingo, 14 de Julho de 2013


After the exams, a weekend upriver with Fulô, the Piver Nugget and Neil, the First Officer...

We left Alhandra on the early morning of Saturday 13th to Valada and returned on the 14th arround noon.

The wind was not so great, under 1kt on the way up and arround 5kt on the bow when we came back, so the sails were kept on their covers and the 5hp Tohatsu was our little helper for the trip.

Here´s a few pictures of the trip.

Fulô is now ashore for routine maintenance so no more sailing until August or September...

See you all then

quarta-feira, 1 de Maio de 2013

Freedom day

Fulô, the trimaran, on the 25th April 2013 club race

segunda-feira, 11 de Março de 2013

One more weekend at the mooring...

Stormy weather has been keeping us tied down for much too long...

My feet are beginning to grow roots from being ashore...

This weekend was no exception...



segunda-feira, 25 de Fevereiro de 2013

Vox Pathfinder 10 mod pack

Here are the mods I've implemented to my Vox PAthfinder 10


1- External speaker jack
2- More powerfull power transformer. The unrated original unit (probably 1A) was replaced by a  2A transformer.
3- Original 14W TDA2030 chipamp replaced by a 20W LM1875 
4- Original distortion circuit's red LEDs replaced by 1n34A germanium diodes
5- Original OPAMPS replaced by JRC4558DD mounted on sockets for chip swapping on the go.

The Pathifinder 10 is a great little practice amplifier that you'll find to be a wolf in sheeps clothing...
The miniature stock speaker does not make justice to the circuit's capabilities and you won't help a very sincere WTF! when you first listen to this little box roar through a proper 12 inch driver. So the first and most cost effective mod is the external speaker jack socket.
Mine is wired in the usual fashion in such cases: Using a switched jack. Whenever an external speaker in connected to the jack, the onboard driver is shut off (thankfully).

As for the electronic mods the changes are somewhat less noticeable, nevertheless very rewarding:

- The 4558s rounded things of a little bit in what concearns the high frequencies;
- The distortion is smoother after the replacement of the original red leds by 1N34A germaniums in the clipping circuit;
- At max output there may be an increase in undistorted sound volume, courtesy of the higher capacity transformer and LM1875 chip in place of the original TDA2030 and tiny transformer.

Although this may be just my ears playing me I've had very good previous experiences in Hi-Fi DIY with the 1875 and the general opinion out thereregards the 1875 as a generaly "better" chip than the 2030, being more dynamically responsive

More on this work in progress later


terça-feira, 19 de Fevereiro de 2013

DIY Optical Tremolo

In the course of this crappy winter for sailing I have to limit my past-time activities to electronics.

After many experiments arround the subject of optical, LDR based, tremolo for guitar I decided to go ahead with the concept of a rotating disc unit. I tend to always prefer electromechanical devices in opposition to purely electric/electronic gadgetry...

Still on the breadboard, I allready found myself face-to-face with the issue that I was more afraid of: DC noise from the motor making it to the audio signal...

So, plenty to reseach and test for the time being. I'll keep posting developments...

Meanwhile here's a picture of the prototype array and respective schematic.

Note the addition of my own do-it-all mighty clean booster. Tremolos don't have to decrease overall output by definition do they?

Next to include:

1- Eliminate DC motor noise issue
2- Depth adjustment: A pot in series with the led
3- Tru bypass switching

See you!

sexta-feira, 14 de Dezembro de 2012


The mighty "Azul" (Blue) is ashore for general maintenance and to repair of a minor crack in the hull.

Azul is a Philippe Harlé Gros Plant (a minitransat 6.5m) built by my dad. She's been sailing arround Alhandra for about ten years now:

terça-feira, 11 de Dezembro de 2012

Arsénio Novo Tube Sound Overdrive

Oh no, another solid state circuit claiming to sound like a tube based one...Well, as you'll find out on your own, this time it's true.

Following a very convincing recomendation from a friend and some positive criticism at the forums out there about this amazing little circuit I finally decided to give it a go.


I never liked the onboard distortions of any of the amplifiers I've owned over time* and I've been in the search for quite a while now for the perfect distortion stompbox to go somewhere in between my tube fueled Guyatone FLIPVALVE PD1 Power Drive and my Guyatone SD2 Sustainer D. Well, I guess the search has ended.

*A cheap Legend 15, a not so cheap but indeed VERY unreliable Rocktron Rampage R80, a massive Crate GX212, a Vox Pathfinder 10, a Fender Champion 600 and a Roland Cube 40

Has it happens this awkward "back to back" PNP-NPN arrangement is likely to be the more juicy distortion you'll ever ear from a solid state distortion ciruit. I'm still trying to force myself to believe that a parts count as low as this can supply the goods in such a competent manner...

Here's the circuit:

P2 being a trimpot to help set the bias (should be set at half, approximetely, or wherever you find the best sound) and P1 being the output level control. No gain, no tone, no complication. The guitar controls are very effective in controling the behaviour of the circuit, as I'm sure you'll have a chance to confirm by yourself. Also, nevermind the switches. Those are there as a part of my own experimentation.

To ease your troubled minds, yes, I've tried a FET buffered input. I didn't like what it made to the sound though, but you're of course  free to go ahead and try one for yourself!

Here's the TINA-TI simulator simulation (@0.25Vpp/1000Hz input)

Instead of a written description of the sound (which would never make justice to the A.N.T.S.O.D) I thought it might be best to record a demo, so here it is:

Recorded using the following soundchain: Yamaha Pac311 (Fender Noisless e Gibson PUs) -> ANTSOD -> Roland Cube 40 (line out) ->PC

I've also made your rookie DIYer's life a bit easier by compiling a stripboard layout of this pearl:

Here's the almost finished product, in a very nice aluminium box available in Portugal at:

Also of great interest is the descriptive memory of the circuit (dated back to '95) by the man himself:

    From: Arsenio Novo
    Date: 04 Jul 95 23:04:50 
    Subject: New Overdrive Circuit


    I've noted that talk on this echo always comes back to the subject of
    overdrive distortion. Whether generated by a vacuum tube amplifier or
    a transistor amplifier there seems to be undeniable differences to me
    as well.

    Lately, I was tinkering with an unusual transistor circuit
    configuration I had come upon a few years ago and made a few
    modifications to the circuit that turned it into one beautiful
    screaming "tube-like" overdrive but without the wall of noise these
    things usually make. When pushed it even makes that distintive
    "zoo-zoo" sound...!!!

    The original circuit was simply a complementary matched pair of
    transistors connected so that all the terminals overlapped. i.e. both
    bases tied together, emitter of the PNP connected to the collector of
    the NPN, and the collector of the PNP connected to the emitter of the
    NPN. Thus:

    This transistor pair is then biased by 2 equal value resistors in each
    of the compound legs, one to the positive supply and the other to
    ground common. The signal is coupled to the base pair leg and the
    output is picked off either of the other 2 legs.

    The result is that the above circuit exhibits the behaviour of a
    multiplier over a range of signal values. It basically performs a
    sin function: in other words a frequency doubler.

    This doesn't have a very good distortion sound though because it is
    rather "burpy and buzzy". However, lately I was toying with the
    circuit when I offhandedly decided to try doing something to it just
    to see what would result.

    After adding a large cap from the NPN's emitter to ground the thing
    went wild on me... WANGO ZE TANGO! SUPREMO DISTORTION! I then
    proceeded to refine the circuit a little more and got a better
    understanding of what it was doing.

    The final schematic follows but first a couple of notes on the
    circuit. The "bias balance" trimmer should be adjusted for a
    symetrical clipping threshold of the output signal as viewed on a
    scope. Short of this it can be easily set by "ear" for the most
    sensitivity somewhere around mid-turn.

    The input should be driven by a lo-z stage if your electric guitar
    doesn't have a built-in pre-amp. You can alter the emitter capacitor
    value in a range from 0.1uF to 1uF in order to obtain various basement
    characteristics but I found the indicated value is a good compromise.
    The input capacitor should not vary much either though because if it
    is made too large the circuit goes balistic and cuts out on the tutti.

    "Tube-sound" Distortion Overdrive Circuit:

    The operation of the circuit more closely resembles a vacuum tube than
    a diode clipper does because of the strong square law characteristic.
    This is due to the negative feedback around both base-emitter pairs.
    This feedback accentuates the junction non-linear behaviour manyfold.

    Thus each transitor drives the other even harder so that the transfer
    curve ends up more logarithmic than is typical of a single transistor.
    In other words: the clipping is gradual and not abrupt like it is in
    the case of a silicon diode. Typically a lot more 2nd harmonic is
    produced as well. As a bonus the waveform folds over on itself when
    the circuit is overdriven!

    Now in the interest of the common good I donate this design to the
    public domain for personal use but retain copyright and reserve all
    rights for any commercial purpose. In other words build one for you
    and your friend but if you have it massed produced for profit I only
    ask a fair share.

    Please, do try the circuit and leave any comments in private at my
    e-mail address: arsenioDOTnovoATmbaDOTorg

By the way, does anyone know who's Arsénio Novo? I'd like to thank him...

Have fun!


segunda-feira, 15 de Outubro de 2012

Regata Belém-Alhandra-Belém

Nem só de trabalho, estudo e afazeres terráqueos me governo...De vez em quando é preciso ir à água...

A chegar a Lisboa de manhã bem cedo.

 Um pouco antes da Vasco da Gama

 A passar Alverca, já depois de acabar a regata (que foi encurtada na baliza 1A)


 A caminho de Alhandra com a Nau dos Corvos e o Nichu's

segunda-feira, 8 de Outubro de 2012

Alhandra à Vela

Há dias que, em Alhandra, a gente se se lembra daquilo para que servem os barcos à Vela...

Oxalá se repitam estes dias, por muitas e muitas vezes...

quarta-feira, 3 de Outubro de 2012

A DIY footswitch for a Roland CUBE

A couple of months ago I bought myself a Roland CUBE 40XL as a stand-by amp for when a gig shows up.

I really like the amp (especially the clean sound) and think it is as close as reasonably perfect an amp should be:

-Fair price (paid 197€ new); 
-Great sound;
-Two (or more) channels
-Predictably reliable and low maintenance (if any)
-Speaker/Amp-Emulated recording/phones output
-Inconspicuous looks;
-Strudy build quality;
-No-nonsense features;
-Loud, and remains clean while loud (if you want it to);

It could benefit from a line-out and external speaker jack (the bigger 80W brother in the line has it!), but hey...For the places where I intend to play I guess these features won't be needed anyway...

The shock came in the time of buying a footswitch... 60€ average price for a Roland FS6 and 30€ for the equivalent Behringer clone? Now, that's expensive... Has anyone explained these people that foostswitches are nothing but, well, switches?

While the use of such gadget is not absolutely necessary for one to enjoy all the features of this amplifier,it sure comes in handy and is highly recommended to explore the built-in 80 second looper at its full capabilities (except for those who have 3 hands)..

But then again: 30 to 60 € for a pair of non latching push buttons ?!?!?

No way, not for my daddy's son...So I came up with this:

Not pretty but, as usual, does the trick...


2 x momentary push buttons (the more sturdy the better)
1 x scrap plastic box (this one is from an old printer's PSU)
1 x piece of 3 conductor wire (this one I made myself by twisting 3 pieces of identical wire using a hand drill)
1 x stereo jack

CIRCUIT: (really simple)

Hope you find any use in this and remember: The quality of any of your DIY builds is only as high as that of the worse component you put into it...



AFTER NOTE: The footswitch will work better if you use normally closed switches. The effects and channel switching will work anyway, but the looper function will only work properly with the switches in normally closed state.

terça-feira, 2 de Outubro de 2012

Insólitos Gibson

A Gibson sempre foi uma marca de que me causou um bocado de aversão pela prepotência com que inflaciona os preços dos seus instrumentos FABRICADOS EM SÉRIE, como se mais não houvesse no mundo quem soubesse fazer guitarras, mas esta é demais:

2 condensadores falsificados (como se mostra aqui por $133 ???

Vergonha...Afinal muitos dos grandes até tocam com Stratocasters...

quarta-feira, 1 de Agosto de 2012

The Anti-Behringer syndrome

Honestly, doesn't it seem that Behringer's competitors are paying people to sign in at home recording forums with the sole purpose of providing generous ammounts of desctructive criticism and deception to all happy Behringer users out there?

I mean, why else on earth would there be so many people disencouraging others to buy good and cheap stuff? Trying to prevent other folks from having endless hours of fun making their own music with a complete studio setup gathered for little more (and often way less) money than a single piece of more appraised brands's equipment.

I've been an avid consumer of Behringer's products for as long as I can remember myself trying to make music and I honestly have little but good things to say from their products.

In what concerns the German brand, my PC based home studio is currently equipped with:

-Several Behringer guitar stompboxes, including a tuner
-A UB502 mixer
-A C3 condenser mic
-A MIC800 microphone pre-amp/phantom power source
-A UCA202 USB audio interface
-More recently a V-AMP 3 and the UCA222 that came along with it

All this can be put together with a few hundred € or so and, from my searches, I cannot find another single manufacturer capable of  even coming close to supply good sounding material at  prices such as Behringer's. In addition to this, Behringer also keeps a very good support site with links to what seems like an endless amount of  manuals and software to get things going.

Recently I've bought a V-AMP3 (new from the store for 54€) and, while searching for reviews before buying, I was amazed by the insane spread of Anti-Behringer syndrome raging all over some of the home-recording forums out there. Reminded me of the ridiculous antipathy Americans (used to?) have for foreign cars (even though they often cost less, are safer, drive faster, burn less fuel and outlast their "bigger and heavier is better" national products). Here are some of the more oftenly used arguments:

"Plastic made"- Disregarding environmental considerations, I can't see how this can be a bad thing. Plastic is lighter, cheaper and not necessarily less reliable than metal for a given application. Lots of things have EVOLVED from metal to plastic through the years and this does not seem to be a bad thing in any other industry other than music's. Are your TVs at home made from steel? Is your cell phone die cast? Would they last longer if they were?

"Bad sounding"-Well, I'm happy that so many other home recorders are wealthy  enough to have their bedrooms stuffed with the finest grades of snake's grease. On my side I prefer to have the so called"bad sounding material" but have SOME material to make my music, while being honest enough to admit that the REAL limitation to my sound is not in my Behringer gear but in my mediocre skills as a singer and guitar player. Plus, what's the point in having audiophile grade gear to record stuff that is to be compressed in to MP3 and delivered as crappy audio streams through MySpace or, worse, burnt down at 16x speed in cheap CDs.

"Unmanageable latency on UCA202 and 222"- This is utterly false. Make sure you have Behringer's correct ASIO drivers installed (available free from their site) and make sure you have your recording software set to operate with them. Are you familiar with the Options tab of your multitracker? If not then Behringer is not to blame.

"Unreliable construction"- In more than 10 years of using their equipment I'm still to experience a fault, but then again, I'm not keen to mishandling my so hardly gathered stuff. Buttons are to be pressed, not hit, and stomp-boxes are to be stepped on, not kicked arround. In a similar fashion, pots are built to be used as pots, not as levers or feet rests.

"Everything that says Behringer has no place in anyone's studio"- Well, such arrogance speaks for itself... No comments needed, really...

I remember, when I started sailing, of the very few who were able to afford heavy weather gear. Douglas Gill, Aigle, Helly-Hansen and a few others where the only available clothing brands and you'd have to be a minister's or bank robber's son to sail in the winter without freezing to numbness. The rest of us had to live with wool clothing, Kispo jackets and landlubber rubber boots. Then along came Decathlon, with the Tribord range and confort was made available to the masses. Everyone could now buy a full equipment for 100€, which weren't even enough for a pair of Aigle sailing boots. The reaction of the sailing community was similar to the Anti-Behringer Syndrome: Decathlon's gear was rubbish. Why? Well, maybe because they were just  plain envious of all us poor old up-river chaps finally being able to sail along (and often ahead) of them under all the weather the sky  and sea could think of throwing at us...

As a friend of mine (who is presently sailing the world all alone) said to me the other day: "What's the point in having a Rolex if a quartz Casio does just about the same?"

It's your choice...You can spend the rest of your life chasing rainbows and dreaming about the so-called "high-end" gear you'll never have or you can be honest with yourself and be conscious of your real needs and start recording next month in a fully equipped home studio built from end to end with Behringer's gear... Don't believe it? Check it out:

Thanks Behringer!