Difference between revisions of "Delay relay"

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* Rajesh's time delay relay video: [https://youtu.be/ma1GSj9XWtM Part 1] / [https://youtu.be/2m3uEKUIWiA Part 2]
* Rajesh's time delay relay video: [https://youtu.be/ma1GSj9XWtM Part 1] / [https://youtu.be/2m3uEKUIWiA Part 2]
* [https://ia804505.us.archive.org/13/items/tek_1977_parts_price_list_number_35a/tek_1977_parts_price_list_number_35a.pdf Tektronix Parts Price List Number 35a (1977) - Page 6.053]

Latest revision as of 10:52, 24 July 2021

Amperite Delay Relays, 1953 (click to enlarge)

Several later tube-era Tektronix oscilloscopes such as the 549, 581 and 585 that already use semiconductor rectifiers for the anode voltages contain a thermal delay relay such as the 6N045T or 6N030T in a circuit that delays turn-on of the main supply voltages until the tubes are warmed up. This is normally not needed in scopes with tube rectifiers because of their inherent slow-start behavior.

When the scope is turned on, a bi-metal strip in the delay relay is beginning to heat up. After the delay time (30 to 60 seconds depending on the instrument), the bi-metal strip closes a contact that energizes the main relay, thereby turning the anode voltages on. One of the main relay's contacts is used to make it self-holding, while at the same time cutting out the delay relay. At this time, the bi-metal strip is beginning to cool so it will be ready to provide delaying turn-on again in the event of a power outage.

The part number is decoded as: 6 − Heater Voltage, NO − Normally Open / C − Normally Closed, XX − delay time, T − B9A (Noval) miniature 9-pin base / no suffix − octal base). For example, a 6NO30T is a 6 Volt filament/heating element with a normally open contact and a delay time of 30 seconds, with a miniature 9-pin base. (The original literature used NO and N0 prefixes interchangeably.)

Part # reference
Tek Part MFR Part Used in
148-0002-00 6NO45 535,545,585,555
148-0006-00 26NO45T ?
148-0009-00 6NO15T ?
148-0021-00 6NO30T 547,549
148-0023-00 18NO30 585A