BNC connector with readout ring: Difference between revisions

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* In most [[7000-series plug-ins]], the ring interfaces with the [[7000 series readout system|readout system]]. The [[Media:Tek-plugin-readout.jpg|plug-in circuit]] uses the shift instructions in time slot 1 to implement the change of range. <br />If the probe includes an Identify switch at the tip, this connects the readout pin directly to ground, encoding the special IDENTIFY instruction in time slot 1.
* In most [[7000-series plug-ins]], the ring interfaces with the [[7000 series readout system|readout system]]. The [[Media:Tek-plugin-readout.jpg|plug-in circuit]] uses the shift instructions in time slot 1 to implement the change of range. <br />If the probe includes an Identify switch at the tip, this connects the readout pin directly to ground, encoding the special IDENTIFY instruction in time slot 1.
* [[7000-series scopes]] only display ×1, ×10 and ×100 factors.  [[11000-series_scopes|11K]], [[TDS series scopes|TDS]], [[:Category:2400 series scopes|2400]] and later recognize [[P6015A|×1000]], ×2, ×5, ×200 and possibly other factors.
* [[7000-series scopes]] only display ×1, ×10 and ×100 factors.  [[11000-series_scopes|11K]], [[TDS series scopes|TDS]], [[:Category:2400 series scopes|2400]] and later recognize [[P6015A|×1000]], ×2, ×5, ×200 and possibly other factors.
* Readout-less [[5000-series plug-ins]] and a number of standalone scopes of the same era, e.g. many of the [[400-series scopes]] such as [[464]], use the ring to detect a ×10 (but not a ×100) probe, and indicate the correct scale factor using front-panel lamps or LEDs. The [[485]] also uses the probe ring and utilizes a TEK custom IC [[155-0076-00]] and three LEDs to indicate ×1, ×10, and ×100 probes.
* Readout-less [[5000-series plug-ins]] and a number of standalone scopes of the same era, e.g. many of the [[400-series scopes]] such as [[464]]/[[465]]/[[475]], use the ring to detect a ×10 (but not a ×100) probe, and indicate the correct scale factor [[Patent US 3725724A|using front-panel lamps or LEDs]]. The [[485]] also uses the probe ring but utilizes a TEK custom IC [[155-0076-00]] and three LEDs to indicate ×1, ×10, and ×100 probes.
* The [[7A14]] plugin uses the same BNC connector with a ring but the ring serves a different purpose, which is to detect the difference between the [[P6021]] and [[P6022]] probes, and switching in appropriate gain and frequency compensation.  The P6021 (or a [[131-0750-00]] adapter for the [[P6019]]) shorts this ring to ground, directly switching three relays connected to −15 V internally.
* The [[7A14]] plug-in uses the same BNC connector with a ring but the ring serves a different purpose, which is to detect the difference between the [[P6021]] and [[P6022]] probes, and switching in appropriate gain and frequency compensation.  The P6021 (or a [[131-0750-00]] adapter for the [[P6019]]) shorts this ring to ground, directly switching three relays connected to −15 V internally.


==Resistor values==
==Resistor values==

Latest revision as of 02:08, 8 June 2024

BNC connector with readout ring
Typical readout spring contact
Different readout contact configurations of P6009 probe: spring loaded pin (left) vs. spring metal clip with two contact points (right)

Many 1970s/1980s Tektronix scopes and plugins have rings around the BNC input sockets that allow the attenuation factor of attached probes to be detected by the scope.

The connector of compatible probes, e.g. P6056, includes a contact pin connecting this ring. A resistor connected to ground encodes the probe attenuation (s.b).

  • In most 7000-series plug-ins, the ring interfaces with the readout system. The plug-in circuit uses the shift instructions in time slot 1 to implement the change of range.
    If the probe includes an Identify switch at the tip, this connects the readout pin directly to ground, encoding the special IDENTIFY instruction in time slot 1.
  • 7000-series scopes only display ×1, ×10 and ×100 factors. 11K, TDS, 2400 and later recognize ×1000, ×2, ×5, ×200 and possibly other factors.
  • Readout-less 5000-series plug-ins and a number of standalone scopes of the same era, e.g. many of the 400-series scopes such as 464/465/475, use the ring to detect a ×10 (but not a ×100) probe, and indicate the correct scale factor using front-panel lamps or LEDs. The 485 also uses the probe ring but utilizes a TEK custom IC 155-0076-00 and three LEDs to indicate ×1, ×10, and ×100 probes.
  • The 7A14 plug-in uses the same BNC connector with a ring but the ring serves a different purpose, which is to detect the difference between the P6021 and P6022 probes, and switching in appropriate gain and frequency compensation. The P6021 (or a 131-0750-00 adapter for the P6019) shorts this ring to ground, directly switching three relays connected to −15 V internally.

Resistor values

please add known nominal values where noted '(?)'

Display Resistance
×1 open
×2 2.2 kΩ (?) [1]
×5 1.8 kΩ (?) [1]
×10 11 kΩ [2]
×20 1.6 kΩ (?) [1]
×50 1.14 kΩ [3]
×100 6.8 kΩ [2]
×200 910 Ω (?) [1]
×500 690 Ω [3]
×1000 470 Ω [1]
Identify short

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 sci.electronics.design thread (2009) about probe readout details
  2. ↑ 2.0 2.1 Tektronix P6056/P6057 Manual
  3. ↑ 3.0 3.1 Tek P5205 HV differential probe teardown @ EEVBLOG (with internal photos)

See also

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