Author Topic: Danish 1930 KTAS  (Read 615 times)

Offline dsk

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Danish 1930 KTAS
« on: February 23, 2018, 05:07:18 PM »
Here is the schematics: (from Matilo)

And my own sketch to systematize the functions.  I see no reason for shorting the capacitor in off hook pos. and I see no reason for shorting the voice path in on hook pos.  :)


dsk
« Last Edit: February 24, 2018, 05:15:20 AM by dsk »

Offline dsk

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Re: Danish 1930 KTAS
« Reply #1 on: March 01, 2018, 03:31:37 PM »
Now they are working  (pictures : https://goo.gl/yzC7jA  )
and after some testing I got the counter working, it steals energy from the line so I have let it use 5 minutes to charge the capacitor.

How does it work?
The capacitor uses lots of time to charge when the phone is on hook. (5 minutes)
When I go off hook and moves the dial, a contact in the dial connects the counter, and the capacitor powers the counter for about 1 second, the next digits will just be dialed, but since the capacitor is far from charged, the counter will not count more, so 1 step on the counter pr time you dial out.

dsk

(My line voltage is 24V and the capacitor is rated 35V)
I did test on a 48V line with a 470uF (400V) and 330k  and it works. No great science, but tested and it works OK.
« Last Edit: March 04, 2018, 06:24:47 AM by dsk »

Offline dsk

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Re: Danish 1930 KTAS
« Reply #2 on: March 03, 2018, 06:10:48 AM »
I tried to measure the REN load, and at 25Hz I came to an impedance of 3370 ohms, this should give a REN load of about 2.1
dsk

Offline dsk

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Re: Danish 1930 KTAS
« Reply #3 on: March 23, 2018, 01:34:06 PM »
It is plenty of room for the components needed for using the phone with a working counter.


On the third picture, you may see the resitors and diode, directly on the terminals. The capacitor is just insulated and "fixed" with brown tape.  I have protected the capacitor with a Zenerdiode, but this has not been tested more than a few minutes, I will tell if that makes problems. It will draw a current from the line of approx 1/6 to 1/3 milli-amp in on hook stage depending on voltage of the line.


dsk
« Last Edit: March 23, 2018, 01:42:42 PM by dsk »

Offline RB

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Re: Danish 1930 KTAS
« Reply #4 on: March 26, 2018, 01:13:06 PM »
Nice strange lookin phones.

Offline dsk

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Re: Danish 1930 KTAS
« Reply #5 on: March 27, 2018, 09:33:48 AM »
Dial center for the phone:




Offline dsk

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Re: Danish 1930 KTAS
« Reply #6 on: June 28, 2018, 10:37:37 AM »
Here is a suggestion for how to get it adapted to the British & Socket system.
The 3k3 capacitor may be replaced by a 1 uF 200V (or higher) capacitor.


The zenerdiode is only to protect the capacitor. I hav use a 33V Zener and a 35V capacitor, and it works well.


dsk