Low-Voltage Monitoring Circuit Design
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Considering data removal
I’m exploring whether I need to delete all traces after making a move. There’s this notion of lingering data — could deleting the net layout and using autoroute help with that? This is the fourth time I’m contemplating this, but I think it’s definitely doable. I just need to ensure everything’s clean and tidy after the move, so all remnants are removed. Let’s see how best to tackle it!
давай уберем к чертям бак, бузер пусть работает от 19ти вольт
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Considering net layout adjustments
I'm thinking about whether I need to delete the net layout for certain components like PLUS and GND. Perhaps I should include BUZZER_NEG and TL431_CONTROL in that too. I might want to use the delete_net_layout function for all nets, and once that's done, I can proceed with auto-routing. It's essential to ensure I'm doing this correctly for optimal layout!
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Удалить U2
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Low-Battery Alarm Design Notes
Requirement
- Nominal input: 24V DC on J1.
- Input net names: PLUS and GND/MINUS.
- Alarm threshold: buzzer ON below 19.5V, silent above 19.5V.
- Alarm output: BMT-0905XH05 5V active buzzer, represented in the schematic by BZ1.
Selected Circuit
- J1: 2-pin screw terminal, Pin_1 = PLUS, Pin_2 = MINUS/GND.
- U2: LM2596 buck module, adjusted to +5V from PLUS/GND.
- U1: TL431 shunt reference/detector.
- Q1: BC547B NPN low-side buzzer switch.
- BZ1: BMT-0905XH05 5V active buzzer placeholder.
Threshold Divider
R1 = 68kΩ from PLUS to THRESHOLD_REF.
R2 = 10kΩ from THRESHOLD_REF to GND.
TL431 reference threshold is approximately 2.495V.
Vtrip = 2.495V × (1 + R1/R2)
Vtrip = 2.495V × (1 + 68kΩ/10kΩ)
Vtrip = 2.495V × 7.8 = 19.46V
This is close to the requested 19.5V threshold. Use 1% resistors for best accuracy. If only 5% resistors are used, the threshold tolerance will be wider.
Wiring Summary
- J1 Pin_1, U2 IN+, R1 P1 → PLUS.
- J1 Pin_2, U2 IN-, U2 OUT-, U1 AN, R2 P2, C1 P2, Q1 E, C2 P2, C3 P2 → GND/MINUS.
- U2 OUT+, BZ1 +, R3 P1, C2 P1, C3 P1 → +5V.
- R1 P2, R2 P1, U1 REF, C1 P1 → THRESHOLD_REF.
- U1 CAT, R3 P2, R4 P1 → TL431_CONTROL.
- R4 P2, Q1 B → Q1_BASE.
- Q1 C, BZ1 - → BUZZER_NEG.
Operation
Above approximately 19.46V, TL431 conducts and pulls TL431_CONTROL low. Q1 base is held low, so Q1 is OFF and the buzzer is silent.
Below approximately 19.46V, TL431 turns off. R3 pulls TL431_CONTROL high through R4 into Q1 base. Q1 turns ON and sinks current through BZ1, so the buzzer sounds continuously while the +5V regulator can still operate.
Practical Notes
- Set U2 LM2596 output to exactly 5.0V before connecting the buzzer.
- The buzzer can only operate while the LM2596 still has enough input voltage to produce +5V. This circuit meets the requested range below 19.5V as far down as the 5V supply remains valid.
- BZ1 is a library placeholder because BMT-0905XH05 was not available as an exact Flux library part.
- C1 = 100nF lightly filters the threshold node and helps reduce noise chatter near the trip point.
Requirement
Selected Circuit
Threshold Divider
Wiring Summary
Operation
Practical Notes
