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

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(My ASR hookup: Add schematic connection column to wire legend)
(My ASR hookup: Added v1.1 schematic with my terminal strip numbers. wire legend nomenclature origins)
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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.
 
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.
  
 +
===Schematic 1.1===
 +
From the original schematic at altairclone I added ASR terminal strip location numbers.
 +
 +
[[File:RS-232 to ASR-33 Teletype Interface Schematic v1.1.jpg]]
 
<source lang="text">
 
<source lang="text">
                            screw       my wire         schematic
+
                              screw       wire             schematic
Signal                     terminal      color           connection
+
Signal                       terminal      color             connection
 +
(Teletype 101 nomenclature)  (on ASR)      (mine)          (altair clone nomenclature) 
 
---------------------------------------------------------------------
 
---------------------------------------------------------------------
Transmitted data send (+)     7          orange          Data to Teletype +
+
Transmitted data send (+)       7          orange          Data to Teletype +
Transmitted data return (-)   6          brown          Data to Teletype -
+
Transmitted data return (-)     6          brown          Data to Teletype -
  
Received data send (+)         4          red            Data from Teletype +
+
Received data send (+)           4          red            Data from Teletype +
Received data return (-)       3          black          Data from Teletype -
+
Received data return (-)         3          black          Data from Teletype -
 
</source>
 
</source>
  

Revision as of 09:33, 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.

Schematic 1.1

From the original schematic at altairclone I added ASR terminal strip location numbers.

RS-232 to ASR-33 Teletype Interface Schematic v1.1.jpg

                               screw        wire              schematic
Signal                        terminal      color             connection
(Teletype 101 nomenclature)   (on ASR)      (mine)          (altair clone nomenclature)  
---------------------------------------------------------------------
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