[GreenKeys] Loop power supply and range spread

[Xavier Andrieu]

Hi everyone,

 

I built a 120V 60mA loop power supply to drive my model 15 Teletype equipped
with a pulling magnet selector (schematic.jpg).

It works, but I found a quite limited range spread - 0 to 30 points - moving
the index arm of the range finder and printing RYRYRY (screenshot1.jpg).

According to Teletype service manuals, I expected more. Is there a
malajustment of the selector unit?

But if I put a 1 microfarad capacitor in parallel with the selector magnet,
the range spread is improved - 5 to 75 points - which is quite fine
(screenshot2.jpg).

 

To understand, I tried to simulate the 2 circuits using LTSpice, but I
didn't succeed as the selector magnet is not a pure inductor.

 

Thank you in advance for your comments or advice,

 

Xavier



---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20181214/d05191c4/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: schematic.jpg
Type: application/octet-stream
Size: 147441 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20181214/d05191c4/attachment-0003.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: screenshot1.jpg
Type: application/octet-stream
Size: 333557 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20181214/d05191c4/attachment-0004.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: screenshot2.jpg
Type: application/octet-stream
Size: 413762 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20181214/d05191c4/attachment-0005.obj>