[GreenKeys] Starting Up an Old Debate

[Bob Camp]

Hi,

There simply has not been enough controversy in the world recently. In 
keeping with modern thought that anybody who is more than 10 seconds 
away from a heart attack isn't really living I feel that we here on 
Greenkeys need to add to the level of stress in the world. Nothing is 
better at doing this than stirring up old questions to which there are 
no answers. These questions are the most useful if there are strong 
attachments to the answers. They are rarely useful in raising stress 
levels if nobody cares about the answers. Since Teletype loop current 
levels are pretty much at the top of people's list when it comes to 
important issues here goes ....

Ok if I put the selector magnets in series I run them off of a 20 ma 
loop.

If I put the *same* magnets on the *same* machine in parallel I run 
them off of a 60 ma loop.

In one case I have 20 ma through each magnet in the other case I have 
30 ma through each magnet.

Obviously something's wrong here. It should be 20 ma and 40 ma - or - 
30 ma and 60 ma ...  not 20 ma and 60 ma.

The phone company had good reasons for using 20 and 60 ma and it worked 
just fine. You fiddled the machine a little and it would tolerate 
running off of either loop current (20 ma per magnet or 30 ma per 
magnet.). A little messing with the spring tension on the selector 
armature was usually about all it took.

The question is: since we don't work for the phone company .... why not 
use a 40 ma parallel loop? It should work just fine. It would use a 
lower power power supply than a 60 ma loop. Think of all the energy we 
could save :) ...  It would be something new to try with 70 year old 
machines ....

	Take Care!

		Bob Camp
		KB8TQ