Difference between revisions of "20ma current loop to RS-232 conversion"

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(Other resources: renamed to Additional)
(My ASR hookup: Add schematic connection column to wire legend)
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<source lang="text">
 
<source lang="text">
Signal                      screw terminal         my wire color
+
                            screw      my wire          schematic
 +
Signal                      terminal     color           connection
 
---------------------------------------------------------------------
 
---------------------------------------------------------------------
Transmitted data send (+)      7          orange
+
Transmitted data send (+)      7          orange         Data to Teletype +
Transmitted data return (-)    6          brown
+
Transmitted data return (-)    6          brown           Data to Teletype -
  
Received data send (+)        4          red
+
Received data send (+)        4          red             Data from Teletype +
Received data return (-)      3          black
+
Received data return (-)      3          black           Data from Teletype -
 
</source>
 
</source>
  
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[[Category:Various]]
 
[[Category:Various]]
 
[[Category:Teletype]]
 
[[Category:Teletype]]
 +
[[Category:Operational]]

Revision as of 09:08, 21 August 2015

20ma current loop <> RS-232 conversion

Vintage PCB

Dig this crazy circuit board man! Still in it's original packaging from Hobby World Electronics in Northridge California.

TTY RS-232 Front.png TTY RS-232 Back.png

Additional Resources

  • Helpful article, Teletype 101 from vintagecomputer.net
  • Another circuit. From [Altairclone] Specifically designed to fit in a Teletype model 33 using only a 12vdc wall wart for power.
  • Another circuit I found referenced on the greenkeys email list

My ASR hookup

I built the circuit described above from the altairclone site. I found the Teletype 101 article helpful for identifying the proper terminal strip locations. The interface works. I set baud to 110, with 7 bits and 'mark' parity in TeraTerm on a windows 8 notebook with a Gigaware USB<> serial convereter.

                             screw       my wire          schematic
Signal                      terminal      color           connection
---------------------------------------------------------------------
Transmitted data send (+)      7          orange          Data to Teletype +
Transmitted data return (-)    6          brown           Data to Teletype -

Received data send (+)         4          red             Data from Teletype +
Received data return (-)       3          black           Data from Teletype -

My Altairclone TTY-RS232 Interface.png Teletype Model 33 ASR terminal block.png