I have not, but I did coincidentally spend the last 15 minutes looking=20
up termination resistors.  Everything points to RS232 and RS485 though,=20
so I want to find a good intro to how to calculate the ideal termination=20
resistor value for my individual-conductors system.

Cheers,
-Neil.



On 12/2/2014 12:44 PM, Bob Blick wrote:
> Hi Neil,
>
> Have you tried adding a load resistor to the receiving end? If you are
> driving the line with a PIC you can use 220 ohms and that will scare
> away most noise.
>
> Cheerful regards, Bob
>
> On Tue, Dec 2, 2014, at 07:36 AM, Neil wrote:
>> I want to amplify some TTL-level signals for better noise immunity
>> through about 10'-15' of wire through a vehicle, and trying to figure
>> out what good options there are.  The data being transmitted is a custom
>> signal (not exactly async serial, and not exactly PWM) of approx
>> 50-100khz, at 5V.  Only one data-line out and one data-line back in.  It
>> works now, but noise issues we've experienced in other areas has me
>> worried, and the board is being revised currently, so I want to add this
>> also.  The wiring/harness is pretty much set in stone so I can't really
>> twist, shield or add wires for differential signaling, etc.  The
>> electronics at both sides of the line is pretty much all I can change.
>>
>> First thought is 74xx245's etc, but have the impression they're really
>> for strengthening signals for driving higher loads over short distances
>> (ie: still chip-to-chip comms).  The last time I used these was  a few
>> decades ago with a Z80 processor.  Not sure I should use it for long
>> wires across devices.  Another option is to use discrete transistor
>> push-pull drivers.  Also, I'm sure I can use a MAX3232 or similar for
>> this.  But are there any other better options?  Looking at digikey gives
>> me 10k+ options, and filtering by package, supply-voltage, cost, etc
>> still nets me a couple thousand options.  Favourite devices?
>>
>> Cheers,
>> -Neil
>

--=20
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