Audible Piezo Buzzer Alarm

The BUZZER-85DB-0 is a compact piezo buzzer designed to connect to the alarm output of TSC pyrometer gauges, providing an audible alert when a programmed temperature threshold is exceeded.

At 4 grams and 22 mm diameter, it can be surface-mounted or recessed into a panel, dash, or bulkhead. It produces 85 dB at 12 VDC—sufficient to cut through engine and wind noise in most enclosed and many open-cockpit environments.

The buzzer operates from 3 to 28 VDC, making it compatible with both 12V and 24V electrical systems.

Why an Audible Alarm Matters

A visual alarm requires the operator to be looking at the display when a threshold is crossed. In many applications—racing, marine, or industrial—that moment often occurs when attention is elsewhere.

An audible alarm provides immediate notification without requiring visual attention. The buzzer’s 4500 Hz tone is aligned with the range of maximum human auditory sensitivity, making it effective in noisy environments.

Gauge Alarm Outputs: Relay vs Open-Collector

Different TSC gauges use different alarm output architectures. The wiring method for the buzzer depends on the gauge type.

Relay Contact Output (PMD-W SuperLite, DPG-SD, DPG-XR-2)

Gauges with relay outputs switch a dry contact that can complete a circuit directly.

• Connect one buzzer lead to the relay contact 
• Connect the other lead to supply voltage 

When the relay closes, the circuit completes and the buzzer sounds.

The buzzer draws ~8 mA at 12 VDC, well within relay contact ratings (1–2A depending on gauge).

Open-Collector NPN Output (MPG-4C, MPG-12C)

These gauges use an NPN transistor that switches to ground (sinks current).

• Connect buzzer positive to supply voltage 
• Connect buzzer negative to the alarm output terminal 

When the alarm triggers, the transistor pulls the circuit to ground and the buzzer sounds.

Maximum load: 0.25A
The buzzer draws far less than this limit.

Improper wiring may result in no output or improper operation.

Quick Wiring Reference

Sound Level in Practice

• 85 dB @ 30 cm (12") at 12 VDC 

Sound level decreases with distance:

• ~79 dB at 60 cm 
• ~73 dB at 1.2 m 

In enclosed vehicles, this is clearly audible above normal cabin noise.

In high-noise environments (open cockpit, racing conditions), positioning closer to the operator improves effectiveness.

Using two buzzers in parallel can increase perceived sound level. Total current remains well within gauge limits.

Frequency and Perception

• Resonant frequency: 4500 Hz ±500 Hz 

This frequency lies within the range of highest human hearing sensitivity, improving detectability relative to lower-frequency tones at the same measured sound level.

Mounting

• Mounting centers: 27.5 mm (1-3/32") 
• Diameter: 22 mm 
• Height: 11 mm 

The buzzer can be:

• Surface-mounted using screws 
• Recessed into a panel for a flush installation 

For best performance, the sound-emitting face should remain unobstructed and directed toward the operator.

Wiring

• Two bare leads 
• The buzzer itself is not polarity-sensitive, but wiring must follow the gauge output configuration 

Voltage Range

• Operating voltage: 3–28 VDC 

Sound output increases with supply voltage. At 24 VDC, the buzzer produces a slightly higher sound pressure level than at 12 VDC.

Technical Specifications

Compatible TSC Gauges

• PMD-W SuperLite 
• DPG-SD 
• DPG-XR-2 
• MPG-4C 
• MPG-12C 

Applications

• Motorsport temperature alarms 
• Marine engine monitoring 
• Industrial temperature warning systems 
• Equipment safety alerts 

Summary

The BUZZER-85DB-0 provides a simple and effective audible alert solution for temperature monitoring systems.

• Compact, low-current design 
• Wide voltage compatibility 
• Compatible with all TSC gauge alarm outputs 
• Effective audible warning in most operating environments