Delay relay: Difference between revisions
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Several tube-era Tektronix oscilloscopes such as the [[549]], [[581]] and [[585]] contain a circuit that delays turn-on of the main supply voltages until the tubes are warmed up. | Several later tube-era Tektronix oscilloscopes such as the [[549]], [[581]] and [[585]] that already use semiconductor rectifiers for the anode voltages contain 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 soft-start behavior. | ||
A main relay that switches the anode voltages is controlled by a '''thermal delay relay''' such as the 6N045 or 6N030 which is housed in a miniature 9-pin glass tube enclosure. | A main relay that switches the anode voltages is controlled by a '''thermal delay relay''' such as the 6N045 or 6N030 which is housed in a miniature 9-pin glass tube enclosure. | ||
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[[Category: | [[Category:Relays]] |
Revision as of 13:26, 19 June 2019
Several later tube-era Tektronix oscilloscopes such as the 549, 581 and 585 that already use semiconductor rectifiers for the anode voltages contain 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 soft-start behavior.
A main relay that switches the anode voltages is controlled by a thermal delay relay such as the 6N045 or 6N030 which is housed in a miniature 9-pin glass tube enclosure.
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. One of the main relay's contacts is used to make it self-holding while at the same time cutting out the delay relay, which is beginning to cool so it will be ready to provide delaying turn-on again in the event of a power outage.
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6N045 delay relay (from 585)
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6N045
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6N045
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6N045