The LaKa-Test is a small device which was designed to check the cabling of power core cables. It uses simple and inexpensive electronics to generate a test sequence to check the connection of all 17 connections within a power core cable between two Harting HAN-E (or equal) connectors. The result is displayed on 17 LEDs. This test device does NOT check for proper isolation voltage and low contact resistivity as might be demanded by official authorities. It does check for broken, missing and swapped connections on all 16 main connections and earth.

The LaKa-Test is based on work done by the German computer magazine C't on test gear for network connections. It is released as free hardware under the GNU General Public License as published be the Free Software Foundation. This device is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

As one can see from the schematic, the LaKa-Test consists of two main parts: the transmitter and the receiver. This two parts are connected via the power core cable under test. The transmitter injects the test pattern by first generating a clock signal. This is done using the two quarters C and D of the 4001 U1. The clock speed is given by the combination of C1 and R20. The second quarter (B) of U1 is used to buffer the clock signal and drive the LED D35. This LED is mounted in the transmitter to monitor the operation. The clock also drivers the two decade counters U2 and U3. Together with the last quarter of U1 (A) they generate a sequence of test patterns to run over the cable. The test pattern are fed into the cable via the resistors R1 to R17.

The receiver of the LaKa-Test consists of 17 low current LEDs, 17 diodes and one resistor. The design of the test pattern is such, that the LEDs are illuminated one by one with all off between 9 and 10.

The LaKa-Test is powered by a 9V battery and consumes less then 5mA. This should give him a very long operation time without the need to exchange the battery. It can be made so compact, that it easily fits into two connector houses. Don't miss to connect the power to the integrated circuits (U1: GND on 7, VCC on 14; U2 and 3: GND on 8, VCC on 16).

To interpret the results just watch the LEDs: if none of them are on less the two cables (including earth) are connected or the battery is low or not connected (check the transmitter LED). If some LEDs are on but some are not, then this (with are not on) denote missing connections. If the LEDs are on but illuminate not all in one row there are connections swapped. Check the connection on the LEDs which are not in the row.

Download:

• GNU General Public License (GPL) (18kb)
• schematic (.pdf, 17kb)