quarta-feira, 28 de setembro de 2016

Calculador de secções "U" quinadas equivalentes a UPNs normalizados

Por equivalência de momentos de inércia, com origem na necessidade de substituir UPNs normalizados por Us quinados no fabrico de certas estruturas.



Para utilização com calculadoras Texas Instruments NSpire ou com o software TI-Nspire Student Software, mas facilmente adaptável para outras linguagens

Eis este e outros programas prontos a utilizar.

Print screens da verificação por FEM (Autodesk Inventor Stress Analysis) para um exemplo equivalente a UPN80 (U quinado com 80x45x9), encastrado, com carga de 1000N aplicados na extremidade:

Tensão equivalente de Von Mises:




Deformação: 



Comentários/ sugestões são bem vindos

Até já!






domingo, 18 de setembro de 2016

A self-imposed Autodesk CFD Simulation exercise

An exercise on a simple air-water heat exchanger.








A reminder of the simulation steps (detailed tutorials aplenty on YouTube):

1- Draw 3D model
2- Import into Autodesk CFD
3- Sanitize geometry (built in tools to close edges, etc)
4- Define the I/O surfaces
5- Fill the voids with the desired fluids
   5.1- Define materials
6- Define boundary conditions
7- Define the simulation conditions (mesh, quantities to display as results (pressure, temperature, velocity,etc...) accuracy, number of iterations...)
8- Solve
9- Define results display mode (plane, traces, points, etc...)
10- Analyse the results 


 Files for practice:

3D.stp here   
3D.ipt file here 
Complete simulation here

Have fun!

Fulô, the 1964 Piver Nugget.

Still sailing in Alhandra, Portugal


quinta-feira, 15 de setembro de 2016

#005 in action again...

#005 in action again...


Last sunday, September 11th 2016.

quarta-feira, 10 de agosto de 2016

quarta-feira, 27 de julho de 2016

Sábado à tarde em Vila Franca

Numa voltinha com o Afonso e o Samora em mais um concerto de divulgação do trabalho "Vagar".

A lap steel #005 em acção, no passado dia de 23 de Julho (2016) na Fábrica da Palavras, em Vila Franca de Xira:




sábado, 16 de julho de 2016

If a dirty bottom slows you down...

...imagine what it does to your boat (or so goes the slogan in PBO).

Fulô at her mooring after this morning's wash...

quarta-feira, 13 de julho de 2016

Texas Intruments Analog Engineer's Pocket Handbook

TI has once again released an excelent design reference tool:

 

Free for free download from
https://www.ti.com/seclit/sl/slyw038b/slyw038b.pdf

sexta-feira, 8 de julho de 2016

Sexta feira

O Fulô à poita, com a omnipresente nortada à perna. Para não variar ...

The second passenger


 

I am a passenger
And I ride, and I ride...
 

quarta-feira, 6 de julho de 2016

Bons, velhos, tempos...

 
 
 
 

Já longe dos tempos em que podíamos velejar todos os fins de semana, lá arranjámos maneira de recordar os velhos tempos a bordo do Fulô, de Alhandra até Valada e volta.






Nortada fresca para cima (fomos de meia vela grande entre o Carregado e Salvaterra) e sem vento para baixo. Deu para queimar a gasolina velha, já com um ano, que vivia a bordo desde o último Cruzeiro do Tejo.





 
Curiosidade: Em Valada 5 trimarans, neste fim-de-semana: O My Dream, o Ideiafixa, o OVNI, o Cabalo Barinho e o Fulô.




Travelin' light, now we can catch the wind
Travelin' light, just let your mind pretend
We can go to paradise
Maybe once, maybe twice
Travelin' light is the only way to fly


 
 
 25 e 26 Junho 2016

sexta-feira, 8 de abril de 2016

An exercise on DIY circuit boards

Still hand-made, still without etching, a lot more tidy...


In this case a voltage regulator for a small solar panel

quinta-feira, 7 de abril de 2016

A reflection on silent crack propagation...

A close-up inspection of Fulô's standing rigging tensioners revealed this:





A close call...

quarta-feira, 22 de julho de 2015

A FEM based comparison study regarding different steel sections with similar specific weights

A college degree stays a long way from providing the empyrical knowledge a designer needs in mundane, everyday work. 

Fast and safe simple designs are often needed for things such as simple levers, hoists and similar devices and I find myself often in need of knowing how different sections, with close specific weights, behave in similar load conditions.

As such, today I decided to establish and share a reference comparison  between similarly weighted steel beams with very different sections loaded in identic scenarios.

The results are as follows, using Autodesk Inventor Professional 2016's Stress Analysis:

Sections properties
Mesh settings

Results
Fixed support at one end, 1000N vertical load at the other (evenly applied across the sections faces)
Displacement

Von Mises stress

Load scenario animation (Von Mises Stress propagation)



Fixed support at one end, 1000N horizontal  load at the other (evenly applied across the sections faces)
Displacement
Von Mises stress


Load scenario animation


Fixed support at one end, 100Nm torsional moment  load at the other (evenly applied across the end faces)
Displacement


Von Mises stress


Load scenario animation

Conclusions:


 -WORK IN PROGRESS-

quinta-feira, 7 de maio de 2015

Fulô waking up on a spring morning


The only (as far as I'm aware) Piver Nugget 24 in Portugal waking at its mooring yesterday.

segunda-feira, 6 de abril de 2015

Mais uma subida do Tejo, de Alhandra a Valada

Desta feita na ressaca de longas semanas em terra por motivos estranhos à Vela, mas tanto ou mais pesados que ela...

Eu e o Neil a bordo do Fulô, o Elebore, o Já Agora, o Sheerazade e, mais tarde, o Falua (3) largaram d'Alhandra rumo a Valada para passar a Páscoa.

A prometida frota da ANC faltou, e nem sei se fez lá falta, tal era a paz assim:







A motor para os dois lados porque o vento não era grande espingarda, mas foi melhor, muito melhor, do que ter ficado em terra...

Aproveitei também para actualizar a minha contribuição para a navegação segura no Rio, já que outras, oficiais e gratuitas, como pertencem ao pagador de impostos e taxas, teimam em não haver:
O Rio continua sujo, assoreado, mal gerido e a piorar...enfim...

Rio Tejo- Ajudas Não Oficiais à Navegação

sexta-feira, 20 de março de 2015

DIY buffered effects loop/ AB box for guitar

A bit of a side project:







Problem:

To build a simple (series) effects loop to add/remove noisy or otherwise malicious components (i.e. crapy bypass pedals) out of the signal chain when not needed.

The solution:

To add the simplest an purest sounding of all buffers to a simple 3PDT based switcher.

Materials needed:

1un. enclosure
4un. jack sockets
1un. 9V battery snap
1un. JFET
1un. 1Mohm resistor
1un. 3k3 to 10k resistor
2un. quality caps (anywhere from .22uF- Higher values means lower frequencies pass. I hear no difference from .47uF onward...)
2un. LEDs
2un. 390ohm resistors
1un. 3PDT stomp switch
1un. SPST toogle switch



Principle of operation:

1- The signal arrives from the guitar at the input jack;
2- It then enters the FET buffer which provides a high impedance input and a unity gain output signal. Great for driving whatever comes next (be it long cables or lots of true bypass effects).
3- From there it goes into the center of the 3PDT where it gets sent either to the OUTPUT or to the SEND jack
4- If sent to the SEND ith thet travel through whichever is connected to the SEND-RETURN and it is thrown into tht output. Simple.

5- The remaining pole of the 3PDT is used to provide a visible status indication (via one of the LEDs).

6- The toggle switch is used to turn the unit on/off.

The unit can be used as a AB box if the instrument is connected to the INPUT and oune output is pulled from the OUPUT and another from the SEND

The assembly results in a super silent unit that draws very little power and does not (at least to my ears) alter the signal in an audible fashion.




Have fun!!!

domingo, 22 de fevereiro de 2015

The Nugget- my first self designed stompbox

The most used effect in my gear, beside reverb, is a mild overdrive or clean boost.

I've built a few varations on EHX's LPB1 but, honestly, feel a bit ashamed of myself for having to copy such simple circuit and not forcing myself to learn enough about circuit design to conceive my own customized yet functional boost pedal.

So today the quest begins and this post will be the diary of the process. Lets see what happens.

1- REQUIREMENTS (22 Feb 2015)
     . High impedance FET input;
     . Dual switchable outputs (A/B) box style;
     . Switchable effects loop;
     . Active tone control;
     . Drive and/or fuzz circuit;
     . Optical output level regulation,
     . Switchable compressor.

So here we go! Keep in touch...

DIY wooden volume pedal

Celebrating the return to (more) frequent posts:

The (still passive) Volume Pedal!








Hopefully this serves as inspiration to anyone seeking a solution to build a simple, sturdy and fully functional expression pedal on the cheap