Re: Technical problem (OT)

Depends on the state of TXD pin3; it is normally at -12V so you have the
anode of the LED 12V positive with respect to its cathode, as it should be
(with a suitable current-limiting resistor in series).

GND(0V)  --- >|---^^^---  -12V

or, forget about GND and just consider the voltages between pins 3 and 5:

+12V --->|---^^^--- 0V

Everything is relative... ;-)

*****************************
----- Original Message ----- 
From: "Scott" <rylos@charter.net>
To: <cbm-hackers@musoftware.de>
Sent: Friday, September 24, 2010 8:57 PM
Subject: RE: Technical problem (OT)


> Nope, there is still a polarity issue. Doh! If the anode was connected to
> the port side of R3 it would light.
>
> -----Original Message-----
> From: owner-cbm-hackers@musoftware.de
> [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Scott
> Sent: Friday, September 24, 2010 8:55 PM
> To: cbm-hackers@musoftware.de
> Subject: RE: Technical problem (OT)
>
> The LED polarity is ok. I've Been troubleshooting software to long.
>
> -----Original Message-----
> From: owner-cbm-hackers@musoftware.de
> [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Scott
> Sent: Friday, September 24, 2010 8:39 PM
> To: cbm-hackers@musoftware.de
> Subject: RE: Technical problem (OT)
>
> Hmmmm... Yes, that would make the ground powered like I stated below. But,
> if it were a true ground it would be grounded on the TI85 side, Zero E.
>
> So my answer to the most excellent question would be that the connection
> to
> the LED should be on the 12E side of R3. Is it supposed to flash? Heh...
> But
> even if this is the case there is the polarity issue correct?
>
> -----Original Message-----
> From: owner-cbm-hackers@musoftware.de
> [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of MikeS
> Sent: Friday, September 24, 2010 7:51 PM
> To: cbm-hackers@musoftware.de
> Subject: Re: Technical problem (OT)
>
> You're assuming that the grounds are actually connected together and at
> the
> same potential; without studying it in detail I suspect they're inverting
> the signal. Everything is relative...
>
> Also keep in mind that RS-232 signals are +/- 12V (e.g. pin 3 is normally
> at -12V which will light the LED quite nicely)
>
> m
> ----- Original Message ----- 
> From: "Scott" <rylos@charter.net>
> To: <cbm-hackers@musoftware.de>
> Sent: Friday, September 24, 2010 5:57 PM
> Subject: RE: Technical problem (OT)
>
>
>> Well, the LED can't work. I was thinking that the pin may be miss-labeled
>> but no... Pin 5 is signal Ground.
>>
>> http://www.diyha.co.uk/electronics/comm1.html
>>
>> Even if the shield had power isn't the polarity wrong?
>>
>> http://www.diyha.co.uk/electronics/comm1.html
>>
>> -----Original Message-----
>> From: owner-cbm-hackers@musoftware.de
>> [mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Ruud@Baltissen.org
>> Sent: Friday, September 24, 2010 4:46 PM
>> To: cbm-hackers@musoftware.de
>> Subject: Technical problem (OT)
>>
>> Hallo allemaal,
>>
>>
>> I think I found the reason for my email problems. A bit further you
>> see "bit......" and that was "bit baCC ngBB MMed". I think there is
>> a porno filter active :)
>>
>>
>> I had to buy a TI-84 for my son for school. Quite interesting, it
>> has a Z80 on board. It has a bit...... USB interface and another
>> bit....... 2-line interface. This particular interface can be
>> connected to the RS-232, please se:
>> http://www.ticalc.org/hardware/cables/serial.html
>> http://www.linkkabel.nl/tutorials/linkkabelmaken/schema.htm
>> The second site is Dutch but the schematic is more clear IMHO.
>>
>> Why this email? I'm puzzled, I have no idea how this can work well
>> with the LED between the two Grounds.
>>
>> If anybody can explain this, please! Thank you!
>>
>>
>> --
>>    ___
>>   / __|__
>>  / /  |_/     Groetjes, Ruud Baltissen
>>  \ \__|_\
>>   \___|       http://Ruud.C64.org
>>
>>
>>
>>
>>
>>
>>
>>       Message was sent through the cbm-hackers mailing list
>>
>>
>>       Message was sent through the cbm-hackers mailing list
>
>
>       Message was sent through the cbm-hackers mailing list
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>
>       Message was sent through the cbm-hackers mailing list
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>
>       Message was sent through the cbm-hackers mailing list
>
>
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