1657
The General Radio 1657 Digibridge is a digital RLC meter, introduced in 1976 1.
Specifications
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Manuals
Links
- Henry P. Hall
- US Patent 4342089, Henry P Hall, Method of and apparatus for automatic measurement of circuit parameters with microprocessor calculation techniques. Filed Dec 12, 1979; Granted July 27, 1982
- How to measure R, C, L using vintage LCR meter @ YouTube
Internals
The 1657 applies a sine wave to the measured device and a precision resistor in series. The average voltage across each is measured using four different phases relative to the input sine wave, for a total of eight measurements. From these, the resistive and reactive components of the tested device can be calculated and displayed.
The 1657 uses a 6503 CPU, which is a 28-pin version of the 6502 with the same instruction set, but fewer address lines. The 1657's firmware is contained in a 2Kx8 ROM, in later versions a 2716 EPROM. A 128-byte SRAM holds scratchpad and the stack.