Info, spice model parameters for DEC pulse transformers?

Joseph Oswald josephoswald at
Wed Jul 18 02:15:56 CDT 2018

I'm trying to model the PDP-1 DEC system models, first with SPICE
(ngspice on Linux), then with VHDL.

I'm struggling to understand the properties of various transformers in
the system module circuits, most importantly (at least, the ones I see
in schematics I want to model)

2 winding T2003 (used in the 1304 delay, 1410 pulse generator, 1540
sense amp, 1607 pulse amplifier)
2 winding T2026 (used in the 1410)
4 winding T2029 (used in the 1201 flip-flop)
3 winding T2033 (used in 1204 flip-flop)
2 winding T2048 (used in the 1607 pulse amplifier, but the maintenance
manual suggests this might be substituted with a T2010?)

The maintenance manual also suggests uses for T2006, T2012, T2017,
T2018, T2019, T2020, T2021, T2023, T2024 are used in modules I don't
have schematics for yet.

Is there any source for information about these? Basic specs? I don't
even know what the turns ratios are for these parts, much less
plausible inductances, so my spice models misbehave pretty badly.

I've also posted a question on Reddit about this


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