The Ausbausystem 5 – Kybernetik III model was announced as ‘In Vorbereitung‘ (in preparation) in the Red Brouchure circa ~ 1976.

The translation of the verbiage is: Further expansion with expansion Lectron system 5 (in preparation) – Cybernetics III – or expansion system Functionsmodelle for biological intelligence processing. The part no. 8 110 063 shows up for the first time in the 1975 price list as the Ausbausystem Funktionsmodelle.

While not shown in the 1st version, the 2nd version of the model by category brochure listed this model under the Technikunterricht category.  The model’s availability was announced for the autumn of 1976.

In the 1977-MAR-01 price list, the Ausbausystem 5 appears for the first time as part number 8 100 072 with a price of 249 DM. No photo or appearance in a catalog of this model has yet surfaced as of October, 2019. SEE BELOW UPDATE SECTION – THIS MODEL ACQUIRED IN MAY OF 2020.

What was the subject matter of the Ausbausystem 5? It was not the described as ‘in preparation’ in the subject matter of Cybernetics III as profiled in the Red Brochure. The actual subject matter was not revealed in the (known) price lists until March 1st, 1982 when the System 500 (the complete self-contained version of the Ausbausystem 5) was also first listed. The Ausbausystem 5 did not have a subject matter description but the System 500 did – Leistungselektronik (power electronics). This model included the Triac, Diac, Unijunktion Transistor, Leistungstransistor npn, and Leistungsdiode blocks.

By the February 1st, 1993 price list, a more complete description of the Ausbausystem 5 was profiled: Logik und Leistungselekronik incl. Lectron Motor. The price was also increased to 399 DM. The System 500 had ceased being listed in the price lists as of the known price list presence of February 10th, 1987.

All the above mentioned price lists are available on the LectronMW documentation page.

The Labor Spezial SK III model incorporated the Leistungselektronik block of the Ausbausystem 5.

UPDATE 2021-JUN-06:

This was a comparatively late released model (1976) and therefore quite rare in terms of commercial product release quantity volume for the LectronMW era.  I had given up hope of ever finding a unit to purchase.  

Miraculously, in May of 2020, a unit appeared on eBay and I won the auction on 2020-MAY-17!  Unfortunately, there was no manual included with the unit but at least most of this very rare model came to me intact.

This unit appeared in the  INELCO style ‘book’ form of packaging rather than the usual cardboard box.  

Note the included Lectron Motor alluded to in the Feb 1st, 1993 price list.

The System 500 unit (a complete standalone iteration like the System 300 as opposed to the auxilliary (ausbausystem) version)  remains an elusive mystery as of this update in 2021!