* Giux-Lab CalcLab Demo Collection * Demo 02 - NE555 transistor-level discrete timer * Test: astable multivibrator, transient analysis * * This is a flattened transistor-level 555 topology adapted for ngspice * from the classic LM/NE555 internal transistor schematic and published * educational transistor-level implementations. * * Important CalcLab compatibility choices: * - no generic '+' continuation after .measure * - no .measure PARAM='expression' * - no BJT AREA multiplier after model name * - three-terminal BJT syntax only * * SPDX-License-Identifier: GPL-3.0-or-later * GNU GPL v3 * ============================================================ * FUTURE CALCLAB VIEWER PRESET METADATA * Currently harmless comments. Intended for the planned feature. * ============================================================ * CALCLAB_PANE 1 V(NE555_OUT) V(NE555_TIMING) * CALCLAB_PANE 2 V(NE555_CONTROL) V(NE555_REF_1_3) * CALCLAB_PANE 3 V(NE555_CMP_THRESHOLD) V(NE555_CMP_TRIGGER) * CALCLAB_PANE 4 V(NE555_LATCH_A) V(NE555_LATCH_B) V(NE555_DISCHARGE) * ============================================================ * SUPPLY * * Power-up is deliberately simulated rather than starting at 12 V. * UIC is used so the transient starts from the physical power-up event. * ============================================================ VCCSUP VCC 0 PULSE(0 12 1m 100u 100u 10 20) * ============================================================ * EXTERNAL ASTABLE CONNECTIONS * * Standard 555 astable: * * RA = 10 kOhm * RB = 100 kOhm * CT = 1 uF * * Ideal first-order estimate: * * T ~= 0.693 * (RA + 2*RB) * CT * ~= 145.5 ms * * f ~= 6.87 Hz * * The transistor-level model will not be perfectly ideal. * ============================================================ RA VCC NE555_DISCHARGE 10k RB NE555_DISCHARGE NE555_TIMING 100k CT NE555_TIMING 0 1u * Trigger and threshold are tied together in astable operation. RTRIG NE555_TIMING NE555_TRIGGER 1m RTHRESH NE555_TIMING NE555_THRESHOLD 1m * Reset held high. RRESET VCC NE555_RESET 10 * Control-voltage bypass capacitor. CCONTROL NE555_CONTROL 0 10n * Output load. RLOAD NE555_OUT 0 10k CLOAD NE555_OUT 0 100p * ============================================================ * INTERNAL 555 REFERENCE DIVIDER * * Three nominal 5 kOhm resistors establish: * * NE555_REF_1_3 ~= 1/3 VCC * NE555_CONTROL ~= 2/3 VCC * * The CONTROL node is the actual control-voltage pin. * ============================================================ R555_R3 VCC NE555_CONTROL 5k R555_R4 NE555_CONTROL NE555_REF_1_3 5k R555_R5 NE555_REF_1_3 0 5k * ============================================================ * THRESHOLD COMPARATOR SECTION * ============================================================ Q555_Q1 NE555_CMP_THRESHOLD NE555_THRESH_E1 NE555_CMP_COMMON QN Q555_Q2 NE555_CMP_THRESHOLD NE555_THRESHOLD NE555_THRESH_E1 QN Q555_Q7 NE555_CMP_THRESHOLD NE555_CMP_THRESHOLD NE555_BIAS_THRESHOLD QP Q555_Q8 NE555_LATCH_A NE555_CMP_THRESHOLD NE555_BIAS_LATCH QP R555_R1 NE555_CMP_COMMON 0 10k R555_R13 VCC NE555_BIAS_THRESHOLD 4.7k * ============================================================ * TRIGGER COMPARATOR SECTION * ============================================================ Q555_Q3 NE555_CMP_TRIGGER NE555_TRIG_E1 NE555_CMP_COMMON QN Q555_Q4 NE555_CMP_TRIGGER NE555_CONTROL NE555_TRIG_E1 QN Q555_Q5 NE555_CMP_TRIGGER NE555_CMP_TRIGGER NE555_BIAS_TRIGGER QP Q555_Q6 0 NE555_CMP_TRIGGER NE555_BIAS_LATCH QP R555_R14 VCC NE555_BIAS_TRIGGER 4.7k R555_R15 VCC NE555_BIAS_LATCH 830 * ============================================================ * LATCH / INTERNAL LOGIC * ============================================================ Q555_Q9 NE555_LOGIC_1 NE555_BIAS_MASTER NE555_BIAS_RESET QP R555_R2 VCC NE555_BIAS_RESET 1k Q555_Q10 NE555_RESET_COL NE555_RESET_BASE NE555_LOGIC_1 QP Q555_Q11 0 NE555_REF_1_3 NE555_RESET_BASE QP Q555_Q12 NE555_LATCH_B NE555_TRIG_BASE NE555_LOGIC_1 QP Q555_Q13 0 NE555_TRIGGER NE555_TRIG_BASE QP R555_R16 NE555_LATCH_B 0 100k R555_R17 NE555_RESET_COL 0 100k Q555_Q17 NE555_LATCH_SET NE555_LATCH_A 0 QN Q555_Q18 NE555_LATCH_A NE555_LATCH_B 0 QN Q555_Q19 NE555_OUTPUT_CONTROL NE555_LATCH_SET 0 QN Q555_Q23 NE555_BIAS_MASTER NE555_BIAS_MASTER VCC QP Q555_Q25 NE555_OUTPUT_CONTROL NE555_BIAS_MASTER VCC QP R555_R7 NE555_OUTPUT_CONTROL NE555_LATCH_A 4.7k * ============================================================ * RESET AND DISCHARGE SECTION * ============================================================ Q555_Q26 NE555_DISCH_BASE NE555_RESET NE555_RESET_DIODE QP Q555_Q27 NE555_DISCHARGE NE555_DISCH_BASE 0 QN D555_D1 NE555_RESET_DIODE NE555_LATCH_SET D555 R555_R18 NE555_BIAS_MASTER NE555_RESET_DIODE 5k * ============================================================ * OUTPUT DRIVER * ============================================================ Q555_Q28 NE555_OUTPUT_PRE NE555_OUTPUT_CONTROL NE555_OUTPUT_EMITTER QN R555_R8 VCC NE555_OUTPUT_PRE 6.8k R555_R9 NE555_OUTPUT_EMITTER NE555_DISCH_BASE 100 R555_R10 NE555_OUTPUT_EMITTER 0 4.7k R555_R11 NE555_OUTPUT_BASE NE555_OUTPUT_EMITTER 220 Q555_Q29 NE555_OUT NE555_OUTPUT_BASE 0 QN Q555_Q30 VCC NE555_OUTPUT_TOP NE555_OUT QN Q555_Q31 VCC NE555_OUTPUT_PRE NE555_OUTPUT_TOP QN R555_R12 NE555_OUTPUT_TOP NE555_OUT 3.9k D555_D2 NE555_OUT NE555_OUTPUT_PRE D555 * ============================================================ * DEVICE MODELS * * Deliberately simple integrated-BJT style models. * ============================================================ .model QN NPN(BF=125 VAF=100 CJE=0.5p CJC=0.5p RB=500) .model QP PNP(BF=25 VAF=50 CJE=0.3p CJC=1.5p RB=250) .model D555 D(IS=1e-12 CJO=1p RS=5) * ============================================================ * TRANSIENT ANALYSIS * * Simulation begins at t=0. * Supply rises at t=1 ms. * * Data retained: * 20 ms -> 2.020 s * exactly 2.000 s of useful waveform * * Requested output spacing = 20 us * Maximum internal timestep = 100 us * ============================================================ .tran 20u 2.020 20m 100u uic * ============================================================ * DEMO 02 V2 CORRECTION NOTE * * File that exposed the issue: * demo_02_ne555_discrete_astable_tran_v1.cir * * HIGH_TIME_2 and LOW_TIME_2 in v1 used mismatched independent * RISE/FALL edge counts while the output starts HIGH. ngspice * therefore correctly returned a negative HIGH_TIME_2. * This is a demo-netlist measurement-indexing error, not a CalcLab bug. * v2 pairs RISE=2 with FALL=3, then FALL=3 with RISE=3. * ============================================================ * ============================================================ * MEASUREMENTS * * No PARAM expressions are used: CalcLab currently rejects them. * TRIG/TARG measurements are kept on one physical line because * generic '+' continuations after .measure are currently misparsed. * ============================================================ .measure TRAN OUT_MAX MAX V(NE555_OUT) FROM=20m TO=2.020 .measure TRAN OUT_MIN MIN V(NE555_OUT) FROM=20m TO=2.020 .measure TRAN OUT_PP PP V(NE555_OUT) FROM=20m TO=2.020 .measure TRAN OUT_AVG AVG V(NE555_OUT) FROM=20m TO=2.020 .measure TRAN OUT_RMS RMS V(NE555_OUT) FROM=20m TO=2.020 .measure TRAN TIMING_MAX MAX V(NE555_TIMING) FROM=20m TO=2.020 .measure TRAN TIMING_MIN MIN V(NE555_TIMING) FROM=20m TO=2.020 .measure TRAN TIMING_PP PP V(NE555_TIMING) FROM=20m TO=2.020 .measure TRAN TIMING_MAX_SS MAX V(NE555_TIMING) FROM=300m TO=2.020 .measure TRAN TIMING_MIN_SS MIN V(NE555_TIMING) FROM=300m TO=2.020 .measure TRAN CONTROL_AVG AVG V(NE555_CONTROL) FROM=20m TO=2.020 .measure TRAN REF_1_3_AVG AVG V(NE555_REF_1_3) FROM=20m TO=2.020 .measure TRAN OUT_AT_100M FIND V(NE555_OUT) AT=100m .measure TRAN TIMING_AT_100M FIND V(NE555_TIMING) AT=100m * Period between the second and third rising edges. .measure TRAN PERIOD_2_3 TRIG V(NE555_OUT) VAL=6 RISE=2 TARG V(NE555_OUT) VAL=6 RISE=3 * High and low times around the second complete cycle. .measure TRAN HIGH_TIME_2 TRIG V(NE555_OUT) VAL=6 RISE=2 TARG V(NE555_OUT) VAL=6 FALL=3 .measure TRAN LOW_TIME_2 TRIG V(NE555_OUT) VAL=6 FALL=3 TARG V(NE555_OUT) VAL=6 RISE=3 * Supply current. SPICE source-current sign may be negative. .measure TRAN ICC_AVG AVG I(VCCSUP) FROM=20m TO=2.020 * ============================================================ * RECOMMENDED WAVEFORM VIEWER TRACES * * Primary pane: * NE555_OUT * NE555_TIMING * * Reference pane: * NE555_CONTROL * NE555_REF_1_3 * * Comparator pane: * NE555_CMP_THRESHOLD * NE555_CMP_TRIGGER * * Logic / discharge pane: * NE555_LATCH_A * NE555_LATCH_B * NE555_DISCHARGE * * Output-driver pane: * NE555_OUTPUT_CONTROL * NE555_OUTPUT_PRE * NE555_OUTPUT_TOP * NE555_OUT * ============================================================ .end