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.

Key Specifications

	— Acquisition —
Bandwidth	100 MHz (20 MHz selectable limit)
Sample rate	2 channels @ 100 MS/s each (two digitizers)
Resolution	8 bit
Record length	500 to 5000 samples per channel
Modes	sample, envelope, average (16 samples), high-resolution, and peak-detect
	— Inputs —
Deflection	2 mV/div - 99.5 mV/div (±1 V offset), 100 mV/div - 995 mV/div (±10 V offset), 1 V/div - 10 V/div (±100 V offset)
Max. input	±400 V (DC + peak AC) up to 100 kHz, derate −20 dB/decade up to 3 MHz, 13 Vp-p above 3 MHz
Input impedance	1 MΩ
	— Trigger —
Trigger modes	edge, error, external and video (NTSC, SECAM, PAL, Sync negative or positive)
Trigger Source	CH1, CH2, External
Trigger coupling	AC, noise reject, high frequency reject, low frequency reject
Trigger levels	±12 divisions (CH1, CH2) or up to ±15 V (External)
Trigger holdoff	500 ns to 10 s
	— Misc —
Interfaces	Ultra SCSI II (50-pin high density SCSI connector) for host connection RS-232 interface (DE-9) Parallel printer interface (DB-25)
Calibrator output	5 V @ 1 kHz (1 MΩ load)
Power	12−24 VDC, 30 W 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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