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The 4218 Piezo Alarm Buzzer is a continuous‑duty electronic alarm designed to deliver a 2800 Hz penetrating tone for safety‑critical and industrial warning applications. Housed in a 42 mm diameter ABS body, it accepts a wide 3–24 V DC supply, making it compatible with 12 V battery banks, 24 V fire panels and rectified mains sources without external regulation. The alarm is rated for extended operation, with thermal characteristics that allow it to remain active throughout a prolonged emergency event without performance drift.
A 2800 Hz fundamental tone cuts through 85–90 dB industrial background noise, providing clear hazard notification even at distance.
Continuous duty rating ensures that the coil and drive circuit remain within safe thermal limits during extended alarm events, including 24‑hour burn‑in scenarios.
The 3–24 V operating window supports direct connection to 12 V and 24 V control panels as well as battery‑backed systems, removing the need for separate voltage adapters.
Through‑hole solder pins and an optional threaded base allow rapid panel or surface installation, with the rugged ABS enclosure suitable for both indoor and protected outdoor use.
The frequency sits between common 2 kHz status indicators and 4 kHz piezoelectric buzzers, giving it a distinctive alert character that is easily distinguished from other machine sounds.
| Parameter | Value | Notes |
| Product Type | Electronic Alarm / Siren | — |
| Sound Pressure Level | Min 90 dB | At 10 cm, per test protocol |
| Resonant Frequency | 2800 ± 500 Hz | Fundamental tone |
| Operating Voltage | 3–24 VDC | Continuous range |
| Rated Voltage | 12 VDC | Nominal |
| Current Consumption | ≤ 8 mA | At rated voltage |
| Duty Cycle | Continuous | Extended alarm events |
| Operating Temperature | -20 ℃ ~ +80 ℃ | Continuous |
| Storage Temperature | -30 ℃ ~ +85 ℃ | Non‑operating |
| Housing Material | Black ABS | — |
| Mounting Type | Through‑Hole | Wave / Manual solder; optional threaded base |
| Dimensions (Dia × H) | 42 × 18 mm | Body only |
| Weight | 12 g | — |
| Cable / Terminal | Pin leads | Through‑hole solder connection |
Fire alarm and evacuation systems that require a continuous, attention‑commanding tone in commercial buildings, warehouses and industrial facilities.
Industrial process hazard warnings such as chemical leak alerts, pressure relief alarms and machine over‑run signals where a 2800 Hz tone remains distinct from lower‑frequency machinery noise.
Security and perimeter protection installations that benefit from a high‑intensity siren for intrusion detection and unauthorised access notification.
Outdoor construction and mining sites where the alarm is used for heavy equipment proximity warnings and blast alerts, protected by an optional weather‑resistant enclosure.
Emergency vehicle auxiliary warning on utility trucks and mobile command centres, powered directly from 12 V or 24 V vehicle supplies.
| Safety System Requirement | HND‑4218 Advantage |
| Long‑range audibility | 2800 Hz output penetrates 85 dB+ ambient noise for effective alerting across large floor areas |
| Extended event duration | Continuous duty rating allows hours of uninterrupted operation without thermal shutdown |
| Power supply flexibility | 3–24 V DC input covers battery, panel and rectified mains supplies without external adapters |
| Rapid installation | Through‑hole pins and optional threaded base reduce mounting time on control panels and machinery |
| Alert differentiation | The 2800 Hz tone is clearly distinguishable from 2 kHz and 4 kHz status indicators |
MEIDI dedicates a separate assembly line to the 4218 Piezo Alarm Buzzer, where each unit is checked for acoustic output, tone frequency and current draw before shipment. The ABS housing is moulded in‑house, and the internal oscillator circuit is calibrated to maintain the 2800 Hz fundamental across the full voltage range. Batch traceability is maintained through a lot code on the housing, linking back to production date and test records.
Reliability testing follows a standard protocol that includes thermal endurance runs at both high and low temperature extremes, vibration exposure simulating transport and installation stress, and continuous operation at rated voltage for 24 hours to confirm thermal stability. The detailed test report is available on request and documents SPL, frequency and current measurements taken under controlled laboratory conditions.
The 4218 Piezo Alarm Buzzer is characterised using a 12 Vp‑p square wave at 2800 Hz, measured at 10 cm in an anechoic chamber. Typical production samples deliver a sound pressure level well above the 90 dB minimum, with current draw consistently at or below 8 mA. The table below summarises the guaranteed performance envelope.
| Item | Guaranteed Value |
| Sound Pressure Level | ≥ 90 dB |
| Frequency | 2800 ± 500 Hz |
| Current | ≤ 8 mA |
| Dimensions | 42 × 18 mm |
For the complete production test protocol and statistical process data, contact MEIDI applications engineering.
1. Can the 4218 Piezo Alarm Buzzer be used outdoors in wet conditions?
The standard ABS housing is designed for indoor and protected outdoor environments. If the alarm will be exposed to direct rain, dust or washdown, MEIDI can supply a version with an IP‑rated enclosure and gasketed construction. Discuss your environmental requirements with the engineering team to select the appropriate configuration.
2. What is the effective range in a noisy factory with 85 dB background level?
With a minimum output of 90 dB at 10 cm, the HND‑4218 provides a noticeable signal‑to‑noise ratio in most industrial settings. The actual coverage distance depends on the acoustic properties of the space; for large areas, multiple alarms can be installed at regular intervals to ensure audibility throughout the facility. Acoustic modelling support is available from MEIDI.
3. Is it safe to run the alarm continuously for a full day or longer?
Yes. The alarm is rated for continuous duty, and its thermal design keeps the coil and electronics within safe limits even during prolonged activation. This makes it suitable for emergency signalling applications where the alarm may need to sound until manually reset.
4. Can the tone frequency be changed from 2800 Hz?
The standard model operates at 2800 Hz. For OEM projects with a specific frequency requirement, MEIDI can review the feasibility of a customised oscillator circuit. Minimum order quantities apply.
5. How do I integrate the alarm into a 48 V or 110 V system?
The standard input range is 3–24 V DC. For higher voltages, a simple step‑down converter or resistor divider can be used. Alternatively, MEIDI can provide a variant with a custom coil winding for 48 V DC operation. Contact the applications team with your system voltage and current availability.
6. Is there a 12 V DC drive option that doesn’t require an external square wave?
The HND‑4218 includes an internal oscillator, so a steady DC voltage within the specified range is all that is needed to activate the alarm. The 12 Vp‑p square wave reference in the test report refers to the measurement set‑up used to characterise acoustic performance in the lab, not a required drive signal for end users.
For acoustic coverage calculations, environmental protection options, sample requests or volume pricing, send your requirements through the contact form. MEIDI’s alarm product team provides technical recommendations, CAD files and installation guidance, typically within one business day.
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