Content
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Kit "IC-Digital-Praktikum"
Kit "Elektronik"
Elektronik Grundbaustein h4G in Kit "ec2" and "hobby4"
Computer Interface
Microcontroller Board
Fork Light Barrier as Rotation and Position Sensor
Acceleration and Tilt Sensor
Author and Links
Kit "IC-Digital-Praktikum"
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On the left you see a picture of the construction kit "IC-Digital-Praktikum", which was released in a first version by fischertechnik in 1977/78. I bought this kit myself in 1979. After having done all modells and experiments described in the according booklet, I thought about extending the kit with further modules IC14 and the relais module "Schaltstufe". However, I did not want to spent the money on a further kit. Furthermore, I owned already 2 relais modules RBII from the set em3. I wanted to make use of them but it was not possible to operate them directly on the outputs of the IC14 module. A relais amplifier would have been needed. This lead to my first electronics board containing 2 copies of the relais amplifier circuit integrated in the relais module "Schaltstufe". |
More than 20 years later I recaptured that idea. I had started to play with fischertechnik again together with my son. We started to work on an elevator which should be controlled by digital electronics. Luckily, I got an opportunity to get prototype printed circuit boards manufactured on a CNC machine. So I started to develop some boards which could be useful for building the electronics for this elevator. The results can be seen in the following pictures.
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Figure Caption: Printed circuit board containing the function of two IC14 modules
The boards were designed using Eagle light (Freeware version) by CADsoft. If you are interested in reproducing these boards you may download the Eagle schematics and board layout files here: |
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Figure Caption: PCB containing the function of voltage regulation 5V and
one IC14 module and four relais amplifiers for
fischertechnik
RBII relais modules (Silberling)
Download: |
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Figure Caption: PCB containing the function of voltage regulation 5V and
one IC14 module and motor driver IC L293D for 2 motors
Download: |
Kit "Elektronik"
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Once having started designing boards, I could not stop it. I continued rebuilding the modules of the fischertechnik kit "Elektronik", which was released in 1982 (at that time I had stopped playing fischertechnik). |
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I placed the function of all 3 modules
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Elektronik Grundbaustein h4G in Kit "ec2" and "hobby4"
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The fischertechnik kits "Elektronik ec2" and "hobby4" contain a module named "Grundbaustein h4G" (Silberling), which is a general purpose differential (or operational) amplifier with additional circuit elements such as potentiometer, voltage divider, diodes, capacitors and resistors. This module is used to realize basic circuits like threshold detection, storage of pulse events (Flip-Flop), clock generation (oscillator), Schmitt-Trigger etc. One application I realized with two of these modules and two relais modules RBI is a control for the traffic lights of a road crossing. So it's always good to have several of these modules or their equivalent electronic function. |
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My idea was then
to develop a self-made board containing the function of four operational amplifiers.
The 14-pin IC LM2902 was my choice for that board, since it operates on a single voltage supply
from 3V upwards. Up to 4 sensors may be connected to the ribbon cable connector or to
the solder pins. The result can be seen in the following pictures.
If you are interested in reproducing this board you may download the Eagle schematics and board layout files here: |
Computer Interface
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I own two of the old
fischertechnik
computer interfaces which operate on the parallel or printer interface of the computer.
The inputs are equipped with 1kOhm pull-down resistors to supress noise and crosscoupling on the input lines.
The disadvantage is that high ohmic sensors such as phototransistors may not be able to switch these inputs directly.
Therefore, I designed a 4-fold differential amplifier stage as an adjustable threshold detector
for the digital inputs E1, E2, E3, and E4.
It can directly be connected with the ribbon cable. If you are interested in reproducing this board you may download the Eagle schematics and board layout files here: |
Microcontroller Board
Features of this board are:- 8 digital input/output ports (each equipped with an own ground line)
- 8 analog input ports (may also be configured as general purpose digital input/output ports, each equipped with an own ground line)
- 4 PWM controlled motor outputs with two L293DNE motor driver ICs
- Infrared remote control receiver SFH5110-38kHz (example: use of your television remote control with RC5 or REC80 code for commands to the µC board), see: Remote Control
- Communication to a second identical board in SPI (serial peripheral interface) mode with slave select via RJ-45 modular cable connection (patch cable)
- Communication to up to 127 devices via I2C interface protocol implemented in software on any two digital ports (example: connect other µC boards or I2C devices such as ultrasonic distance sensors), see the I2C software library by Peter Fleury for integration in WinAVR GCC, especially the pure software implementation with "i2cmaster.h" and "i2cmaster.S"
- 8 bit µController ATMEGA16 (or pin compatible ATMEGA32 or ATMEGA8535)
- Up to 8 MHz internal RC oscillator clock or 16 MHz with optional quartz crystal resonator (not included in part list or placement view, insert "free flying" at two solder pads next to XTAL pins)
- Code may be written in C with WinAVR GCC (Gnu C-Compiler, free download) or in Assembler with AVR Studio (free download from Atmel web site)
- Code may be downloaded to the internal code-flash memory via the parallel port of your computer (see below the board "programmer"). For this you need an old fashioned legacy type PC with parallel printer port (they become pretty rare these days).
- During code download, the board must be powered. Either with an external source via the voltage regulator, or via the parallel port of the PC (the metal bridge J3 on the board "programmer" must be inserted). However, current supply via the parallel port of the PC is limited to a few mA. Therefore, the jumper JP1 on the board "ATMEGA16" must be opened to disconnect power supply for the L293DNE's during downloading, since they draw 20mA each even if inactive.
Figure Caption: µC board ATMEGA16 (older version not including all described features)
Figure Caption: Eagle board view (latest version including all features) of µController Board ATMEGA16
If you would like to build this board, you may download the file ATMEGA.zip containing all necessary files (eagle schematics and board, *.eps with mask pattern for PCB film, bill of material list, *.doc with mask pattern for printing, placement view, pin assignment, example program template.c {with board specific setup} and Makefile for use with WinAVR etc.). ATMEGA.zip
It's a two-sided board with half Euro Card format (100mm x 80mm). Two of these boards fit on one Euro Card format (100 mm x 160 mm). Therefore, I recommend to produce two of these board at a time. With the *.zip file I provide a combined mask pattern for a single UV exposure of two ATMEGA16 boards on one Euro Card format.
There are 38 vias on this board. I used a technique inserting a short wire into the vias and soldering them on both sides. Also take care that all devices on the top layer (such as electrolytic capacitors), whose pads are connected to top layer routing, must also be soldered on the top side.
Figure Caption: Pin assignment of the digital port of the board ATMEGA16
Figure Caption: Pin assignment of the analog port of the board ATMEGA16
Figure Caption: Pin assignment of the motor port of the board ATMEGA16
The software may be coded in C and compiled using the GNU Compiler Collection GCC under WinAVR (free download). You may use my files "template.c" and "Makefile" contained in "ATMEGA16.zip" for a quick start. The compiled code (intel hex format) is then loaded into the Atmel microcontrollers flash memory using the sp12 programming hardware (self-made board connected to the computer’s parallel interface named Ken’s Dongle after its creator Ken Huntington) and software (download available) developed by Steven Bolt, the founder of Pitronics in the Netherlands. A further programming software, which is compatible to the sp12 hardware, is provided under the name TwinAVR by Roland Walter (Berlin, Germany).
I designed a board named "programmer" on the basis of Steven Bolt's description, which fits to the pin assignment of the RJ-45 western modular jack of my µ-controller board "ATMEGA16".
Figure Caption: Eagle board view of board "programmer"
If you would like to build this board, you may download the file programmer.zip containing all necessary files (eagle schematics and board, *.eps for PCB film, bill of material list etc.). programmer.zip
Here is a nice application of the board "ATMEGA16" with a fischertechnik model: ARTIST: Two wheel balancing robot built using fischertechnik components
Fork Light Barrier as Rotation and Position Sensor
Figure caption: Application of fork light barrier (using a different PCB) with segment disc for speed regulation of the two motors of a track vehicle
The sensor described here is based on very well known and simple principles:
a segment disk rotates in a fork light barrier and
If you would like to build this board, you may download the file Gabel_Sharp.zip containing all necessary files (eagle schematics and board, *.eps for PCB film, etc.). Gabel_Sharp.zip The picture on the right hand side shows an example for a segment disc with 32 black and 32 transparent segments (64 signal changes per full rotation). You may print several copies of the picture on the right in high resolution on a transparency, each disc with a size of 4 cm in diameter. Then cut the discs out of the transparency and mount them with glue on a fischertechnik wheel 23 red (part 36581) with 23 mm diameter fitting to the 4 mm axis. Segment_Disc.gif (1211 x 1211 pixel resolution) |
Figure caption: Eagle board view of PCB with fork light barrier 
Figure caption: Graphic (Segment_Disc.gif) for high resolution printing of a segment disc onto a transparency |
Figure caption: Top view (component side) of board with fork light barrier |
Figure caption: Bottom view (solder side) of board with fork light barrier |
Acceleration and Tilt Sensor
For the balancing robot referenced above, one of the sensors needed was an acceleration sensor (for tilt measurement with regard to earth's middle). I built a two axis acceleration sensor board with SMD componenents using ICs from Motorola for 5V operation, MMA2260D (x-axis, orientation towards the electric connectors) and MMA1260 (z-axis, orientaion towards the top). The range is ±2g on each axis. Output are two analog voltages between 0 and 5V (one for each axis). These outputs can be directly used on an analog input line of the fischertechnik computer interfaces (old parallel interface) and for my own µC board ATMEGA16. The electrical connectors fit to the standard fischertechnik 2.6mm-plugs. Here you see a picture of the board. The size of the board is 28 mm x 49 mm.
Figure Caption: SMD Board for 2-axis acceleration or tilt measurement
Figure Caption: Eagle board view of board "TiltXZ" with 2-axis acceleration sensor
If you would like to build this board, you may download the file TiltXZ.zip containing all necessary files (eagle schematics and board, *.eps for PCB film, etc.). TiltXZ.zip
Author, Links and Disclaimer
Send an email to Dirk Uffmann
Go to my index page with links to my other projects
Go to my page on ARTIST: Two wheel balancing robot built using fischertechnik components
Go to my page on a fischertechnik Elevator with 4 Levels and Automatic Sliding Doors