low level serial - addendum
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Posts: 46,084
Forgot to mention, the incoming signal swings from -250mv to +250mv relative
to ground.
I am in need of a device for converting low level serial to ttl levels.
The incoming serial data is only a few hundred milivolts p-p squarewave.
Does anyone know of a chip designed for this purpose, or am I going to have
to resort to using a comparator?
I figure a 139, 239, 2901, or 3302 would handle the temp extremes this app
calls for (339's tend to malfunction below 32'f, 0'c)
to ground.
I am in need of a device for converting low level serial to ttl levels.
The incoming serial data is only a few hundred milivolts p-p squarewave.
Does anyone know of a chip designed for this purpose, or am I going to have
to resort to using a comparator?
I figure a 139, 239, 2901, or 3302 would handle the temp extremes this app
calls for (339's tend to malfunction below 32'f, 0'c)
Comments
volts unless you provide a positive offset voltage so the input
signal never goes below zero.
--- In basicstamps@y..., "FalconWireless Tech Support - KF4HAZ"
<techsupport@f...> wrote:
> Forgot to mention, the incoming signal swings from -250mv to +250mv
relative
> to ground.
>
> I am in need of a device for converting low level serial to ttl
levels.
> The incoming serial data is only a few hundred milivolts p-p
squarewave.
> Does anyone know of a chip designed for this purpose, or am I going
to have
> to resort to using a comparator?
> I figure a 139, 239, 2901, or 3302 would handle the temp extremes
this app
> calls for (339's tend to malfunction below 32'f, 0'c)
>Forgot to mention, the incoming signal swings from -250mv to +250mv relative
>to ground.
>
>I am in need of a device for converting low level serial to ttl levels.
>The incoming serial data is only a few hundred milivolts p-p squarewave.
>Does anyone know of a chip designed for this purpose, or am I going to have
>to resort to using a comparator?
>I figure a 139, 239, 2901, or 3302 would handle the temp extremes this app
>calls for (339's tend to malfunction below 32'f, 0'c)
2 NPN transistors, 2 resistors.
1st NPN: Emitter grounded, Base & collector tied together and to the Base
of the 2nd NPN and a 10K pullup resistor. Input signal goes to the Emitter
of the 2nd transistor. Collector of the 2nd transistor is output to stamp:
should also use a 10K pullup resistor.
Make sure that you place the transistors close together or even touching:
they require thermal coupling to reduce the effects of temperature changes.
This should work over the industrial temperature range: -40C to +70C.
dwayne
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
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