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    • #7458

        Hi all,

        Oh boy, do I have so much fun with the legacy parts and the modified amplifier module !

        I almost forgot about the rest of the 1205 system 🙂

        Let’s make a marriage  between analogue and digital : a super sensitive sound flip flop !

        From about 5 meters (!) distance, even a tiny whisper will make our lamp go on or off 😆

        And if you have some music playing, the lamp will start to flicker on the beat of the music.

        This is made possible thanks to the Germanium transistors build inside the cubes.

        These start to conduct with only a voltage of 0.3 Volts between the Base and Emitter.

        So, here’s the circuit setup :

        Sound Flip flop

        A short explanation :

        Noise is picked up from the speaker and fed to the 2 stage amplifier. The output of this amplifier goes to an emitter follower which is only used as a impedance buffer for the Schmitt trigger module.

        The output of this Schmitt trigger goes to a Flip Flop module which drives a lamp via a impedance transformer block.

        Since our Flip Flop divides the input in 2, the flickering of the lamp is very good noticeable when playing some music.

        Even from a far distance, only a tiny whisper will make our Flip goes Flop 😛

        Many greetings

      • #7460

          This is so cool Frank and a real first for the Lectron System legacy ‘digital’ circuits!  Thank you so much.  I can see your next project of making a DAC.  

          Any chance of fitting the meter in this circuit?  Movement and light, lots of fun.

          Thanks again professor Frank, you continue to amaze!


          • #7468

              Hi All,

              a very nice and useful schematic indeed!

              That remembers me to Experiment 89 and 90 of the old Egger/Braun Base manual:

              •  89: Soundlevel Meter (Schallpegelmesser)
              •  90: Burglar Alarm (Geräuschwarnanlage)

              This two schematics were used / planned for the Lectron Bastelsätz sets (see there, including videos)

              The problem of 90 is that the light only shows with a short flash any noise activity, but never leave ON until another noise will happen. So the light control is quite nice but not practicable because I would like to see the light for more than several seconds (= alarm !). Here the use of a Flip Flop will be the solution, like in your circuit.

              Another planned Bastelsätz was the Remote Control Device (Fernsteuerung) – see there incl. video -, presumably a similar circuit which switch ON a light / TV set / radio and – with a second noise e.g. hand clapping – make it switched OFF. To switch a 230 VAC unit I have to use a relay with power contacts (not the Lectron relay). This is a dangerous area so it’s not recommended for assembling by non-experts!

              The schematic:

              Please note: the internal wiring of the Flipflop and the Impedance transformer are placed on a separate PCB and on the mainboard, see photo above. A control LED will show the active state.

              As always: the combination of linear and digital functions (and – if meaningful – with relay) is a good possibility for understanding electronics!



              • This reply was modified 3 years, 10 months ago by Michael.
              • This reply was modified 3 years, 10 months ago by Michael.
              • This reply was modified 3 years, 10 months ago by Michael.
              • This reply was modified 3 years, 10 months ago by Michael. Reason: Changed font and size styling for easier reading. Also embedded hyperlink to Bastelsatz page
          • #7469

              Hi Gunther,

              You continue to amaze me with these Lectron kits.

              Great info !
              From the schematic, I see that the triggering is somewhat different.
              They had to use another transistor as amplifier and used a diode rectifier for the AC audio signal.

              With the improved amplifier, the signal is so strong (about 3V pp) that it can be used as a trigger for the Schmitt trigger.
              I like the approach of the Lectron kit as well !

              Maybe the published circuit can be adapted to this approach !

              I will let you know,


              • This reply was modified 3 years, 10 months ago by Michael.
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