[WriteLog] Parallel Interface

2001年7月06日 20:21:46 -0500

Thanks to George and Jim for their input.
I'm thinking I'll just fix up the parallel port interface but install a 
second LPT in the machine.
The cards are cheap and easy to setup. If something goes terribly wrong 
I've still got a printer port.
Really looking forward to contest season this year from the "black hole". 
HI HI!
Thanks again.
Kevin, NリRKX
At 05:47 PM 7/6/01 -0400, you wrote:
>Kevin,
>You could use the Comm port CW line and the 4N33 CW circuit to drive your
>level translator.
>>But the LPT port is a TTL output (5 VDC and Gnd) and does not have
>sufficient "drive" current to drive the LED in the 4N33. The LPT port can
>"sink" enough current but that current must be supplied by another 5 VDC
>power supply with its own return line connected to the LPT computer Gnd
>line. I have tried to drive the LED from the LPT port here and it is both
>risky and unreliable. It is risky in that you may burn out the LPT drivers.
>It is unreliable because when you limit the drive current you get may or may
>not provide sufficient current to adequately switch the 4N33 output stage
>and key your circuit.
>>I have thought of trying to steal the additional 5 VDC from the computer
>itself but have not tried it yet. I just use the 2N2222 circuit directly
>and have not had any ground loop problems in that circuit in several years
>of contesting. It will drive your level shifter nicely. I have used that
>circuit here also... (with a TS 530)
>>George .. W1ZT
>----- Original Message -----
>From: Kevin Stover
>To: Writelog@contesting.com
>Sent: Friday, July 06, 2001 5:03 PM
>Subject: [WriteLog] Parallel Interface
>>>Hello all.
>In response to my last message it was suggested that I use an opto-isolator
>in the parallel interface to the rig to absolutely isolate the computer from
>the rig.
>Can I swap out the 2n2222 in the parallel circuit for the 4n33 of the serial
>in the documentation.
>Either way this circuit is going to have to drive the grid block keying
>circuit of my last post.
>>Writelog documentation: http://www.willinet.net/~kstover/cwint.jpg
>>Grid block keying circuit: http://home.att.net/~jacksonharbor/gridbsch.pdf
>>Thanks for the input.
>>Kevin, NリRKX
>
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