All 3 references in the title are small, 3 pin, AM receivers in a chip with minimal external components.
I remember seeing then in schematics at electronics magazines many years ago, somehow expensive (the Ferranti ZN414) at that time, so, never got one. Until now, the equivalent TA7642:
... previous image is the testing board, run with the following schematics and it worked:
..my small changes in red. During the night with this it was possible to get some stations and also a beacon, I guest the cap/coil tuning range was going inside the LW band. The coil, don't remember where I got it, probably from some scavenged radio.
Tested also with variable capacitor to ground:
..was about to try with the varicap in place when I "fried" the TA7642 by touching the input with the soldering iron while powered on, bad luck and crappy iron, pretty sure the varicap version will work too!
Anyhow it's a funning litle device, good enough for a very simple AM receiver.
Have a nice week!
2 comments:
Good on MW,I have added a Pot on the 100k feed to the input,adjusting makes a difference on weak stations😀
Did same with soldering iron
Works good on MW band
I have put a potentiometer on the feed through the 100k resistor either a fixed resistor in series to limit voltage to the TA7642 input.
It helps when adjusted for weaker stations😀
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