[GreenKeys] Current loop not providing (enough) current

[Jim Cooper]

On 21 Sep 2019 at 11:37, Zach Zarzycki wrote:

> Well - I have my 26 hooked up though
> the volpe board and have managed to
> get as far as when I type on the
> teletype's keys the terminal window
> on the laptop accurately displays
> what I've punched up. 

I have a couple of comments/suggestions.... 

First off, I don't see why so many are trying 
to use "boosters" and such to make a loop 
supply ...  Use 'real' transformers and power 
supply components -- diodes, capacitors, etc. 
Even if you take 2 'filament transformers' 
( 110v to 6v ) back to back like an isolation 
transformer ...  much more rugged and less 
flaky than voltage "booster" stuff. 

Second, set up your 60mA loop by itself ... 
adjust it for 60mA.  Then put the 26 selector 
magnet in series with the 26 keyboard in series 
with the loop.  Make sure the 26 runs 'closed' ... 
marking.  Type on the keyboard and be sure 
the printer prints on the paper correctly.  Then 
add ONE more part of the circuit at a time, and 
be sure that added part is working properly.  

w2jc