I discovered that you can inject a signal into pin 14 of this chip, removing
the necessity for fiddling with the internal oscillator. The internal
oscillator is great for LC circuits............you merely place the tuned
circuit between pins 13 and 14, and it flies!
You just have to set the injection level so that the buffered signal at pin
12 is right around 320mV p-p.
Pete
Pete KE9OA wrote in message
...
One thing that I forgot to mention............if there is enough interest
in
that spreadsheet, I will post it up on my website.
Pete
J M Noeding wrote in message
...
On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA"
wrote:
Has anybody used the oscillator section of the tda1572 with a crystal
type
of configuration. I looked at the tda1072 application note in one of my
old
data books, and I don't see how that circuit would even oscillate. I
know
that it can be done, because the Linn Kudos FM/AM tuner does this with
the
chip's on-board oscillator.
20-30 years ago TBA120 (Texas SN76660N) was a popular device and used
in several numerous applications in Europe, particularly in Germany
and Nederland, some of these constructions were published in the
"Elektor" magazine (believe the original was Dutch),
among the applications I remember:
RF mixer
phase detector
product detector
audio mixer
oscillators on audio as well as RF
syncronous AM detector
etc
It is no real principal difference between devices like TDA1047,
TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you
have the schematic of the inner functions, find the phase relation
between the limiter input pins and quadrature output connections you
should be able to make an xtal oscillator
I wrote some note to Radcom (G3VA) about TBA120 applications 20 years
ago, but cannot remember today which applications I tested, believe it
was found a maximum frequency around 15MHz.
The later devices are designed for low-power with low maximum
frequency, while the older like Motorola MC1357P (not MC3357) has been
used as 70MHz ATV demodulator and was published in such magazine
around 1984, one MC1357P was also used as RF limiter. But if your
device is a low-poer-type, it might not operate at high enough
frequency where you have an xtal to connect.
Believe I have some applications on one of my pages, but lack the
index, so I'll have to use google to search on my own pages, hi
73
Jan-Martin, LA8AK
http://home.online.no/~la8ak/c.htm
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