HW_ILoop_Power
... hand trimmed potentiometer for each line
TODO
All teletypes (with current loop interface) are designed for a current of 40mA. The receive unit (magnet coil) has a typical voltage drop of 15V. Taking into account the additional voltage drop in the interface circuits, a power supply voltage of about 20V should do - in theory.
BUT! The switching speed of a magnet coil depends directly on the intermediate circuit voltage - in this case the power supply voltage. On practical experience the intermediate circuit voltage should be at least twice the magnet coil voltage.
ADDITIONAL BUT! Most teletypes are used with a FSG (dialing device). This has also a relay in the current loop with an additional voltage drop. Some relay circuits (especially for "Wahlbereitschaft" = ready for dial) need a higher voltage (60V) to work as expected.
Working supply voltages with interfaces above:
| Teletype | Working voltage |
|---|---|
| Lo15 | 24V |
| T37 | 24V |
| T68 | 24V |
| Teletype | Working voltage | Full Working voltage |
|---|---|---|
| Can transmit, receive and dial but the ready-for-dial-lamp lits always. | Can transmit, receive and dial with ready-for-dial-lamp working as expected. | |
| T37 | 50V | ? |
| T68 | 55V | 85V |
| T100S | 24V | 60V |
TODO More Details...
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Local use
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i-Telex
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Advanced Topics
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Tools & Gadgets
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TW39 (current loop)
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ED1000 (FSK modulation)
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V.10 (TeKaDe FS200, FS220)
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SEU-M-board based
- with Austrian AGT (Ö-AGT, current loop)
- as replacement for SEU-B card inside LO2000, LO2001, LO3000