TWD120

Manuals – Specifications – Links – Pictures

The Tektronix TWD 120 Digitizer allows a Windows PC to be used as a digital storage oscilloscope. It is rated at 100 MHz, has two input channels and an external trigger input. It connects to the host PC via a SCSI bus.

The TWD 120 is about the size of a laptop, and was supplied with a soft case. It was intended to be used in conjunction with a laptop running Windows 3.1, and was apparently manufactured for GE for use by medical device field technicians.

The Adaptec ASPI SCSI driver is required for the software to communicate with the digitizer. SCSI configuration can be tricky.

Specifications

Acquisition

• Sample rate: 2 channels @ 100MS/s each (two digitizers)
• Analog bandwidth: 100MHz on both channels (20MHz selectable limit)
• Resolution: 8 bit
• Record lengths: 500 to 5000 samples per channel
• Modes: sample, envelope, average (16 samples), high-resolution, and peak-detect

Analog inputs

• Voltage:
  • ±400V (DC + peak AC) up to 100kHz
  • -20dB/decade up to 3MHz
  • 13Vpk above 3MHz
• Impedance: 1MΩ
• Coupling: DC, AC, GND
• Ranges:
  • 2mV/div - 99.5mV/div (±1V offset)
  • 100mV/div - 995mV/div (±10V offset)
  • 1V/div - 10V/div (±100V offset)

Trigger

• Modes: edge, error, external and video (NTSC, SECAM, PAL, Sync negative or positive)
• Source: CH1, CH2, External
• Coupling: AC, noise reject, high frequency reject, low frequency reject
• Levels: ±12 divisions (CH1, CH2) or up to ±15V (External)
• Holdoff: 500ns to 10s

Misc

• Display: N/A on the unit. Depends on the host PC.
• Ports:
  • Ultra SCSI II (50-pin high density)
  • RS-232 (DE-9)
  • Centronics-A (DB-25)
• Probe compensation output: 5V @ 1kHz (1MΩ load)
• Power:
  • 12-24VDC
  • 30W max

Links

• More info, including good information on SCSI configuration and work arounds for using later versions of Windows
• EEVblog teardown comments and pictures

Photos

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