[GreenKeys] Current loop not providing (enough) current

[Ralph Mowery]

I can't say about the 26, but I have a 19 working off one of the boost
converters set to around 90 volts. The converter is powered by a 12 volt 1.5
amp wall cube.  The resistor is a power resistor with a slicer to set the
resistance.  I don't recall the value, but it was set so that around90 volts
I had the 60 ma current.  I adjusted the voltage on the boost converter to
fine tune in the 60 ma.  

Does the 26 units run open with no current on the loop like the 19 ?  

If so does yours run open if you cut off the power ?

Ralph ku4pt


-----Original Message-----
From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Zach Zarzycki
Sent: Saturday, September 21, 2019 11:37 AM
To: 'Green Keys'
Subject: [GreenKeys] Current loop not providing (enough) current

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.

However, typing on the teletype doesn't cause the keys to punch paper, and
typing on the laptop keyboard won't cause the teletype to do anything.

I'm set up with a boost converter and a 12v 3amp power supply that SHOULD be
supplying roughly 60mA at 97 volts though the loop after being boosted and
then ran though about 1.6k wire wound resistor (600 ohm and a 1kohm in
series, both 25W rated). 

The problem is when I read the voltage out of the booster, it shows  97v,
but the most I've seen any amperage on any test point is 25ma, a far cry
from 60ma. I'm wondering this this is possibly the reason for the computer
keyboard not being able cause the keyboard close the magnet and select a
letter then type. 


My gut says maybe? But I find it very odd though that I can make the
greenkeys act as a keyboard, so maybe I'm missing something else.

Zach 


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