Archivo de la categoría: Electronics

Friction powered Longboard

This is a redesign of the Rotor Flettner project. The effect works after testing it mounted on a windsurf board but it has a potential flaw: Magnus effect has a smaller force than the wind pulling you to the side. The result is that you go more in the wind direction than in the direction that you really want to go. The equivalent to having a very small sail.

But anyways it was a lot of fun to make it and having already the engine and the structure to mount it I thought, why not to try doing something with it :)

And it works, went about 2 kilometers back and forth after discovering I made some design errors and that friction is not my friend. Engineering lessons learnt:
1.- Control cables of the engine should not be touching the floor
2.- Engine should transmit power using some similar material as the wheel
3.- Friction generates heat and 50% of the battery or more is wasted (maybe good for the winter)

Skate and position detail

Wheel coupling with engine

New project: Portable Flettner-Rotor (Longboard)

flettner_longboard
3D model available on tridiv.com

The idea come while reading “Symmetry of Sailing” by Ross Garret. The german engineer Anton Flettner was the first to use this physical principle as propulsion engine for a ship in 1922.

The still difficult part and open points to discuss that I have in this Winter project are:

  • Material to use in the main structure. The goal is that is light, when possible less than 10 Kilos,  but resistant since it needs to provide lift.
  • Motor weight: 170 g  Speed controller: 230 g  . Cables + Battery: Aprox.  2 K. Making a total of 2.5 Kilos weight.
  • Still open to discuss: At what speed needs the cilinder to roll and what would be the ideal diameter to provide enough momentum to move 70 Kg in a Longboard (I thought about 40 cm diameter).
    The chain relation between the motor and the cilinder to have the right speed and force. Ex: 10 spin motor: 1 spin cilinder
  • And to end the question: What kind of lift will this generate on a 10 Knots wind, coming from the optimal point, let’s say 90 degrees left or right from the cilinder.

Peggy version 2.0 Led panel receiving serial data

This is a modification we did to a Peggy2 led panel.

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JP1 y JP2 enable the “serial hack” (Map at the footer of this post)

The steps to follow if you want to try this:

  1. Install this program in the Peggy through USB using Arduino software. This little program is just a loop that renders in the led panel putting Peggy in “Serial mode”
  2. Make the electrical brige like shown in the picture
    Originally the bridge is from P2 to JP3 and JP4 so enabling Peggy2 to be programmed. To make this point clear, after changing the bridge you will not be able to install a program in Peggy, you will just send serial data through the USB
  3. Download processing and try out programs designed to send data to Peggy
    There are some examples at the end of this entry

This is the hardware modification explained by Carlos Fasani

Originally Peggy 2 has 2 bridges (0 ohm resistances) in jumpers JP3 and JP4.

With this connection the lines A_Sel and B_Sel of the multiplexor 74HC154 (U2) that controls rows 0 to 14 are connected to RXD (pin 2) and TXD (pin 3) of the microprocessor ATmega (U1).
But as this communication legs are needed to recevied serial data we take out JP3 and JP4 leaving the serial line desconected from 74HC154 (U2).
And then we bridge JP1 and JP2 connecting A_Sel and B_Sel from multiplexor 74HC154 (U2) to SDA (pin 27) and SCL (pin 28).

This way Peggy is ready to receive data and light the ROWS at the same time.

*UPDATE*
Windell, the Chief Scientist of Evil Mad Scientist replied to our email pointing out some important details that can be useful to make this even better:

 It  looks like you’ve run the two jumpers as follows:

  * First jumper: From the left side of JP2 to the right side of JP4, and
  * Second jumper: From the left side of JP1 to the right side of JP3.
 If I’m seeing this correctly, then your modification is exactly equivalent to putting the two jumpers in locations JP1 and JP2.  (See the attached screenshot for verification of how this is wired.)  And if so, you *should* still be able to reprogram the board, even after making the modification.

Thanks a lot for your clarification. I still didn’t tried this out since I forgot my soldier equipment but for sure it will work out.
Windell also pointed out that the latest Peggy 2 versions are already capable of receiving serial data and operating the full display at the same time, so long as you have the SER option selected on the board, and you are using our Peggy2Serial library and its RecvSerial.pde sketch
Peggy2serial

ATTACHED:
https://github.com/martinberlin/sketchbook
Electronic design of Peggy2 (pdf)

Jay’s projects. Jay was one of the first ones to send serial data and video to Peggy2

Modificación para hacer funcionar en serie la Peggy2

Esta es una modificación que hicimos para poder enviar datos seriales a través de USB al panel de Leds Peggy2.

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JP1 y JP2 habilitan el “serial hack” (Mirar plano adjunto en esta entrada)

Los pasos a seguir para poder hacer que esta modificación y enviar datos serie son:

  1. Instalar este programa en el Peggy a través del software de Arduino. Este programa la peggy en modo “Recibir datos por serie”
    Basicamente si le echan un vistazo a el codigo, es un loop eterno que recibe los datos serie y los imprime row por row en la placa de Leds. 
  2. Hacer el puente este como esta indicado en la foto (JP1 y JP2 a P2)
    Originalmente los puentes están desde P2 a JP3 y JP4 que son para tener una exacta compatibilidad con Peggy2. Para dejar en claro este punto, al hacer este cambio la placa Peggy queda fijada en modo de recepción serie con lo cual no se puede programar mas desde Arduino sino que le enviaremos datos por Processing.
  3. Descargar el processing.org y meter programas preparados para funcionar con la peggy en modo “serie”

ADJUNTOS:
https://github.com/martinberlin/sketchbook
Repositiorio en Github con ejemplos para probar esta modificación

Descargar Peggy2 plano electronico (pdf)

Jay’s projects. Jay fue uno de los primeros en enviar datos por serie a la Peggy2

Fe de erratas para Peggy2 mapa: Populate ONLY  (JP1 and JP2) OR (JP3 and JP4).  Select: JP1 and JP2 to enable the “serial hack” or Select: JP3 and JP4 for exact compatibility with Peggy 2.0.

Una cosa interesante que he descubierto intentando subir mis codigos es que WordPress.com no te permite hacer upload de cualquier fichero, con lo cual a partir de ahora subiré todos los codigos en Github.