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

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[[File:TTY RS-232 Back.png|400px]]
 
[[File:TTY RS-232 Back.png|400px]]
  
==Other resources==
+
==Additional Resources==
 
* Helpful article, [http://www.vintagecomputer.net/teletype101.cfm Teletype 101] from vintagecomputer.net
 
* Helpful article, [http://www.vintagecomputer.net/teletype101.cfm Teletype 101] from vintagecomputer.net
 
* Another circuit. From [[http://altairclone.com/teletype.htm Altairclone]] Specifically designed to fit in a Teletype model 33 using only a 12vdc wall wart for power.
 
* Another circuit. From [[http://altairclone.com/teletype.htm Altairclone]] Specifically designed to fit in a Teletype model 33 using only a 12vdc wall wart for power.

Revision as of 08:43, 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.

Signal                      screw terminal          my wire color
---------------------------------------------------------------------
Transmitted data send (+)      7          orange
Transmitted data return (-)    6          brown

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

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