20ma current loop to RS-232 conversion
Contents
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.
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.
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 -
