observation · Voltage Intensifier Circuit · computed
Scotchn series-opposing bifilar + C0G (no diode) rings at ~1.27 MHz, not the ~430/136 kHz the meter's 137 µH predicts. Real differential/leakage L is single-digit to ~15 µH (pending C0G value). Ring holds ~17 µs at constant envelope, then stops abruptly,
- Bench — Scotchn, Discord #neuralstan20-testing 2026-10-05 (two Rigol photos).
- Setup — Af joined to Bf (series-opposing). C0G test cap between As and Bs; value not yet stated. No diode. CH2 across the C0G, CH3 gate, CH4 MOSFET drain (probe ratio unconfirmed). Drive: 2930 Hz single pulse per gate, gate time 14322 µs, PSU 4 V / 0.006 A.
- Readings — Freq(C4) 1.2738 MHz; Vpp(C2) 24.6 V; Vpp(C3) 2.20 V (gate, 2 µs/div capture); Vpp(C4) 3.41 V. Drain and gate spikes are locked to the CH2 cycle.
- Read off the photos (rough) — the ring starts at the drain trigger edge and keeps a near-constant envelope for ~17 µs (~22 cycles), then stops within a cycle or two. At 2 µs/div the period appears to stretch from ~0.75 µs to ~0.95 µs (≈1.33 → ~1.05 MHz down-chirp).
- Derived (lumped, L = 1/((2πf)²C)) — 1 nF → 15.6 µH; 1 nF + 1.122 nF interwinding → 7.4 µH; 10 nF → 1.56 µH. The meter's 0.137 mH would need 114 pF total to ring at 1.27 MHz, so that reading (0.14 Ω of reactance against 7.8 Ω DCR at 160 Hz) is overstated by roughly an order of magnitude.
- Consequence — the #3488 hypothesis (leakage + interwinding C ≈ 406 kHz as the source of the ~300→200 kHz packets in #3477) is WEAKENED. With µH-scale leakage, 300 kHz would need tens of nF.
- The ring is not a free exponential decay. Something feeds it for ~17 µs: candidates are the primary dump through the MOSFET (avalanche/flyback window) or gate pickup re-biasing a logic-level FET (2.2 Vpp hash on the gate). The down-chirp fits Coss rising as Vds falls, but that is unverified.
Basis
- Recorded
- Published
- 6 Oct 2026
- Stanbot
- v3
- Source Ref
- Scotchn Rigol captures (Freq C4 1.2738 MHz, Vpp C2 24.604 V), Discord #neuralstan20-testing 2026-10-05; vic_calc expression; amends #3488
- Notebook Id
- 3490
scotchn bifilar leakage-inductance series-opposing ringing gate-pickup