observation · Voltage Intensifier Circuit · computed
No C_t, loop closed through 1 kΩ, 10.3 Ω moved 150 mm away on twisted pair: CH1 tail unchanged (1.92 Vpp, >1 ms decay). The loop time constant (~0.14 ms) and the voltage needed across 1 kΩ both rule out real current; resistor pickup also unlikely. Next: p
- Scotchn, Discord #neuralstan20-testing 2026-09-30. Setup — As–A–AF–[150 mm twisted pair]–10.3 Ω–diode–Bs–B–BF–1 kΩ–As; C_t removed; CH2 removed; trigger CH3 (MOSFET) 9.96 mV, Normal. CH1 100X diff across the 10.3 Ω, + on the cathode side.
- Capture (160 µs/div, CH1 500 mV/div) — CH1 Vpp 1.92 V. Pulse-synchronous swings grow over the 10-pulse burst to ~1.7 V, then a step to ~1.6 V decays slowly to ~1.0 V at ~1.1 ms. CH3 49.4 mV. Same shape and size as with C_t in and with the resistor on the card.
- Reasons it is not real loop current — (1) the loop L/R ≈ 140 mH / 1 kΩ ≈ 0.14 ms, but the tail lasts >1 ms; (2) 1.6 V / 10.3 Ω ≈ 155 mA through 1 kΩ would need ~155 V across the pot, more than the windings produce (tens of volts per winding at 4 V drive); (3) the 60 mW supply budget (#3464). Moving the resistor 150 mm from the core on twisted leads did not change the signal, so pickup in the resistor coil or the lead loop is unlikely. Shorted-lead CM test was flat earlier.
- Remaining suspect — the differential probe or channel's response to real fast differential spikes (LF compensation or overload recovery), or channel crosstalk. Invariance to C_t, resistor position and loop closure fits a measurement effect.
- NEXT — (a) pot lifted (fully open loop): real current must be zero; (b) swap the two differential probes, or use the other probe on CH1. If the tail follows the probe, it is the probe.
Basis
- Recorded
- Published
- 1 Oct 2026
- Stanbot
- v3
- Source Ref
- Scotchn Rigol capture, Discord #neuralstan20-testing 2026-09-30; extends #3464
- Notebook Id
- 3465
scotchn diode-shunt probe-artifact time-constant