661: Difference between revisions

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=== Delayed Pulse Generator ===
=== Delayed Pulse Generator ===
The delayed pulse generator is a [[tunnel diodes|tunnel diode]] circuit that produces a negative-going 250 mV pulse with a risetime of about 150 ps and a pulse width of about 400 ns. The output is a 50 Ω [[GR-874 connector]].
The delayed pulse generator is a [[tunnel diodes|tunnel diode]] circuit that produces a negative-going 250 mV pulse
with a risetime of about 150 ps and a pulse width of about 400 ns.
The output is a 50 Ω [[GR-874 connector]].
When a timing unit (e.g., a 5T1) triggers, it sends a pulse through pin 10 of the J4 interconnect to the delayed pulse generator, which regenerates the pulse.
When a timing unit (e.g., a 5T1) triggers, it sends a pulse through pin 10 of the J4 interconnect to the delayed pulse generator, which regenerates the pulse.
There are three versions of the 661 delayed pulse generator (serial numbers 101 through 2829,  2830 through 3459, 3460 and up).
There are three versions of the 661 delayed pulse generator (serial numbers 101 through 2829,  2830 through 3459, 3460 and up).
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Based on the available schematics, the 661 appears to have been designed in 1961.   
Based on the available schematics, the 661 appears to have been designed in 1961.   
:''During what years was it manufactured?''
:''During what years was it manufactured?''
:''Why is it that the 661 has a dedicated high-speed coaxial interface between the sampling unit the timing unit while later 560-series sampling systems ([[3S2]], [[3T77A]], etc.) simply use the regular plug-in connector and mainframe wiring harness for routing trigger and timing signals between the two units?''
:''Why is it that the 661 has a dedicated high-speed coaxial interface between the sampling unit the timing unit
while later 560-series sampling systems ([[3S2]], [[3T77A]], etc.) simply use the regular plug-in connector
and mainframe wiring harness for routing trigger and timing signals between the two units?''


Some 661s have a 41 pin [[Bendix connector]] on the rear panel, perhaps to allow the 661 to be interfaced to low speed data acquisition equipment or a computer. This is essentially a pass-through from J2 & J3, the secondary multi-pin connectors on the vertical & horizontal plug-ins. These connectors carry switch position information (number, magnitude & units) and clock & gate pulses. Not all plug-ins had this 2nd connector; the [[5T1A]] does, while the [[5T3]] does not.   
Some 661s have a 41 pin [[Bendix connector]], J5, on the rear panel, perhaps to allow the 661 to be interfaced to low speed data acquisition equipment or a computer.
This is essentially a pass-through from J2 & J3, the secondary multi-pin connectors on the vertical & horizontal plug-ins.
These connectors carry switch position information (number, magnitude & units) and clock & gate pulses.
Not all plug-ins had this 2nd connector; the [[5T1A]] does, while the [[5T3]] does not.   


The 661 has a 137°F/58 °C [[thermal cutoff]].  In practice, it doesn't run hot.
The 661 has a 137°F/58 °C [[thermal cutoff]].  In practice, it doesn't run hot.