Charge Test DSCN0467

This is the 2nd of the two supervision tests on card #5.
The other supe test is the "classic supervision test" shown in a separate video. This Charge Test is modeled after one that was in area code (312) back in the early 1970s. I think it was in Chicago. There were never very many of these. Only a couple in the old network. Featured here are the indicator LEDs on the card front and you can also see the neon lamp
way at the back of the card that is in series with the line to convey ring signal
to the card. It flashes when line polarity reverses. The real nice thing about using a neon lamp in series to detect ringing is that at normal 48 volts, this lamp is an open circuit. It only conducts when the neon glows and that happens when the voltage gets much over 70 or so volts. The neon bulb trick goes way way back for me, I used it starting about 1970 to act as a toll mute for incoming calls on my parent's phone line.
For anyone who wants to follow along, here is what the quick reference guide says about Card #5.
Supervision Test Lines. There are six green LEDS on the left, and four red LEDs on the right.
From left to right the (6)green ones are :
#1 Line 2 (673) ring detect
#2 Line 1 (563) ring detect
#3 555 timer doing timeout
#4 4017 ringing counter on zero
#5 Line Select Relay (on = line 673)
#6 Polarity Detect Relay
Then the (4) red ones are:
#7 500 cycle tone coupling relay
#8 Office Noise Coupling Relay
#9 Tick Relay
#10 Supervision Relay

[@AlexisKasperavicius]

Sweep tone test?

[@leroyjones6958]

Yes. Card #4. Sweep Tone Tests. There are two sweep tests on that card. Coming up soon. Stay Tuned. 😎