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11A34: Difference between revisions
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a switch selecting the calibrator or signal input, and an [[M474]] buffer amplifier. The calibrator signal is turned off inside the plugin when not in use. | a switch selecting the calibrator or signal input, and an [[M474]] buffer amplifier. The calibrator signal is turned off inside the plugin when not in use. | ||
The attenuator module output feeds the | The attenuator module output feeds the non-inverting input of the [[M377]] amplifier IC through a (blue) 50 Ω transmission line, one per input channel. The cable lengths set a standard delay per plugin. | ||
The M377's | The M377's inverting input is connected to the [[ACVS]] (Analog Control Voltage System) output. | ||
The (differential) display outputs of the four amplifiers are hard-wired in parallel and drive the mainframe’s 50 Ω per side input impedance. The same is true of the trigger outputs of the four amplifiers. | The (differential) display outputs of the four amplifiers are hard-wired in parallel and drive the mainframe’s 50 Ω per side input impedance. The same is true of the trigger outputs of the four amplifiers. | ||
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The AUX signals emerge from each M377 amplifier as differential signal with a 200 Ω source impedance per side. | The AUX signals emerge from each M377 amplifier as differential signal with a 200 Ω source impedance per side. | ||
External (on the circuit board) 66.5 Ω shunt resistors on each AUX output bring this down to the 50 Ω source | External (on the circuit board) 66.5 Ω shunt resistors on each AUX output bring this down to the 50 Ω source impedance specified by the 11k plug-in interface. | ||
impedance specified by the 11k plug-in interface. | |||
See also the block diagram below. | See also the block diagram below. | ||
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The [[11A32]] and 11A34 were originally intended to use [[Intel 8052]] microcontrollers. | The [[11A32]] and 11A34 were originally intended to use [[Intel 8052]] microcontrollers. | ||
However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip | However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip | ||
ROM size. [[Doug Haines]] found an alternate supplier of 8051-compatible chips (OKI Semiconductor) | ROM size. [[Doug Haines]] found an alternate supplier of 8051-compatible chips (OKI Semiconductor) that offered a 16 KByte on-chip ROM, and that's what the plug-ins wound up with. The finished code size is about 14 KB. | ||
that offered a | |||
The 11A34 also contains a Dallas Semiconductor DS1220Y NVRAM storing last settings, calibration constants, and instrument serial number. | The 11A34 also contains a Dallas Semiconductor DS1220Y NVRAM storing last settings, calibration constants, and instrument serial number. | ||
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==Links== | ==Links== | ||
* [[11A-series plug-in NVRAM replacement]] | * [[11A-series plug-in NVRAM replacement]] | ||
{{Documents|Link=11A34}} | {{Documents|Link=11A34}} | ||
{{PatentLinks|11A34}} | |||
==Pictures== | ==Pictures== | ||