50th Anniversary Model – FM Stereo Receiver

I am very excited to announce (in 2015) that RWO has officially announced the 50th anniversary limited edition model to be added to the Lectron System  product line. Only 50 units of this model will be made guaranteeing it as a collector’s item for years to come.

This model was developed and prototyped as a collaboration between Günther Stabe and Gerd Kopperschmidt with the support of Norbert Cahn von Seelen, the Lectron System product manager.  Mr. Kopperschmidt designed and engineered the productized model blocks.

The new 2488 FM Stereo Receiver block ready for production.

The 2488 block in action with other new blocks to create a stereo FM receiver with a digital frequency counter (another new block (Order no. 2619) and its Technical Note can be downloaded/reviewed here).

The following is the original 50th anniversary model announcement as presented on the Lectron.de website (Notes:  2021-JUN-17 – This introduction has since been removed with the new Lectron.de website redesign but is presented below for historical purposes).

Lectron will soon be celebrating its 50th anniversary. At the suggestion of Michael Peters, a committed American fan who researches and documents the history of the company (lectron.info), there is a special component in a limited edition of 50 pieces, namely an FM stereo receiver for headphone and loudspeaker reception (Order No. 2488).

The receiver is based on the Sony IC CXA1238S and the amplifier IC TDA2822 (2×1.7W at 4Ohm); it is housed in a 9-module and is operated with 9V, display via blue LED. The headphones are connected via a 3.5mm jack socket, their supply line serves as an antenna, and there is another connection for a rod antenna. The transmitter selection via capacitance diodes is done with a potentiometer, the tuning voltage is led to a contact (e.g. for display purposes). A red LED indicates reception, a yellow one whether it is stereo. Another potentiometer adjusts the volume for headphones and loudspeakers; In addition, the LF output signals from the CXA1238S are routed to contacts for connecting an external amplifier.

In the course of this development, which was thankfully supported by Günther Stabe, additional VHF stereo receivers and amplifier modules were created.

An FM stereo receiver for headphones (3.5mm jack socket) and speaker connection based on the IC GS 1299 in a 2-part module (Order number 2486). The headphone lead serves as an antenna and there is an additional connection for a rod antenna.

The setting is made using five pushbuttons:

– Transmitter run-up
– Transmitter run-down
– Off / On, display via red / blue LED
– Volume increase
– Volume decrease

The matching NF amplifier 2x3W at 4 ohms (Order no. 2489) is based on the amplifier IC PAM8403. It is housed in a high 3-way module and is switched on with the volume potentiometer. A red / blue LED indicates its operating status.
Very important: The leads for the right and left loudspeakers must not have a galvanic connection.

Finally, both of the above units, VHF receiver and amplifier, are combined in a flat 4-part module (Order No. 2492). The headphone connection (3.5mm jack socket) is again an antenna, the amplifier can be put into stand-by mode via a control input (apply ground). The operating displays are shown separately with two red / blue LEDs. The loudspeaker leads must not have a galvanic connection.

A stereo potentiometer 2x50kOhm (Order no. 2232) in a 2-component module completes the new releases.

The proof of concept for the Lectron System FM Stereo Receiver was developed by Mr. Stabe and successfully demonstrated to Mr. Steffen Pohl, the then business manager for the Lectron System product line, on 2014-DEC-09.  

Mr. Kopperschmidt then developed his own version that would be more suitable for integration into the overall Lectron System product line while also developing several ancillary but allied blocks to enhance the FM Stereo Receiver model’s experiment curriculum.

Sadly, with the illness and then passing of Mr. Norbert Cahn von Seelen during 2015 – 2016, these blocks were never developed into a productized model for marketing and sale.

A formal instruction manual was never created either but Mr. Kopperschmidt did prepare a Technical Brief note which is available for downloading/review here.