[GuentherParticipant]

To have a break – no more receivers today… – I would like to introduce an early Lectron block with the integrated circuit TAA151 from Siemens (=TAA293 from Valvo) containing 3 transistors and 4 resistors. This photo was found in the RWO archive Frankfurt/M.

It was produced in small numbers and handed out to external authors like Mr. Max Gürth or Mr. Hartmut Birett. May be Mr. Gürth gave the hint for production. This block was delivered with normal (white) and clear cover, see photo of Mr. Gürth’s huge Lectron Labor cabinet. I couldn’t resist and built a replica:

Mr. Gürth used this block as a part of a planned “Lectron Leistungselektronik” set around 1970, where he introduced power transistors, thyristors, rectifiers, UJT, FET, flashlight (there will come a topic from me, too), first ICs and a lot more. Michael has all this material in his archive. One of this application with TAA151 was the following:

This is an AM receiver with a push-pull output stage. I like more to have complete stages within one block to prevent trouble with possible contact problems (I will come back on this theme in another topic). So I offer this solution for an AF amplifier:

For the loudspeaker should be used a better quality like Frank explained in an early proposal.

Unfortunately I found no Part-No. for this block. Other prototype blocks like RC-combination #8056, microphone #8067, connection blocks #8068…8070, buzzer #8073 and the Demo block Radio (!) will follow soon.

Best,

Günther

• This topic was modified 5 years, 2 months ago by Michael. Reason: Changed font and size styling for easier reading and added subject matter links
• This topic was modified 5 years, 2 months ago by Michael.

[LectronFanModerator]

Hi all,

This is a real cool old School amplifier chip. Reminds me a bit of the BA306 chip used in the Science Fair electronic kits like the 150 in 1 kit, which I got for Christmas around 1978.

The advantage of these chips is the fact that they use the same matched transistors with good temperature stability. And also that they use only a small place on the PCB.

Later on, these were replaced by Operational Amplifiers such as the LM741.

Great circuit you got here !

Greetings

• This reply was modified 5 years, 2 months ago by Michael. Reason: Changed font and size styling for easier reading
• This reply was modified 5 years, 2 months ago by Michael.

[GuentherParticipant]

Hi Frank,

a couple of years ago I purchased a “150-in-1” set in a wooden case on a fleamarket. The “IC” was a thinfilm module, the contacts were spirals (corroded, with a grey dust on it) which had to be connected with lots of wires… criss-cross, rather terrible. So I sold it again…

The next simple amplifier/driver IC was the TAA435, used in several portables and car radios in Europe.

Here is my more powerful amplifier with a TAA861 and the AD161/AD162 pair:

I preferred having a heatsink (no melting of the plastic cover) instead of a schematic, so I pasted the covers below the snapshot for better understanding. This amplifier will work best with a more powerful loudspeaker box. In my office I use two of these self made zero-cost speakers (12 x 19 cm = 4.7 x 7.5 inches) with a wonderful sound:

But who would like to use the Lectron design, perhaps this is a nice idea:

Using the “standard” Lectron loudspeaker block (with a modification) it might be useful to connect headphones as an alternative:

Best,

G.

 

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