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The Mini-Mac Sound-Relay-Alarm instrument is a sound activated device that triggers two relays from sound. Instruments are factory set to trigger at approximately a 90dB sound level. This setting can be internally adjusted for greater or less sensitivity.
There are two independent alarm relay circuits that are activated from the special microphone within the instrument. Each relay circuit has their own LED-lamp-indicator. When a relay is activated, it’s circuit LED will also light. Relay-1 one has a yellow LED, relay-2 two has a red LED. The relay is a dry-contact relay, normally open until triggered. When triggered, the relay closes for a zero-ohm contact.
Two independent relay circuits allow the instrument to be more versatile. For many applications, relay-1 can be the warning relay and relay-2 can be the final relay, usually adjusted for a little louder than the warning relay trigger.
The Mini-Mac was built for outdoor use; however, it is recommended for a longer instrument life, not to have direct sunlight on the microphone. The microphone is an omni-directional microphone that can pick up sound from many source directions, even the possibility of reflected sound. The microphone is moisture resistant and can operate in a large range of outdoor temperatures. Mount the Mini-Mac so that the microphone will not be covered with water, bugs, or other debris.
The Mini-Mac can be powered from a wide voltage range: 12-24VDC.
Relays are capable of 240VAC, 5 Ampere maximum, load switching.
The steel chassis is powder coated for a durable long life.
Operational life of 10+ years is expected indoor. Outdoor life may be less.
Mini-Mac sensitivity can be adjusted two ways. The threshold, Alarm-1 Set, Alarm-2 set, single-turn potentiometers, and the 25-turn overall gain potentiometer, P1.
The Threshold potentiometer can raise or lower the threshold of trigger within the instrument. There is an approximate numbered scale for each circuit. Notice that “90” is the center point for each single turn threshold potentiometer.
The gain-potentiometer P1 is factory set typically at 50%. With this setting and with the threshold potentiometers set at 90, an approximate 90 dB sound source should trigger on the relay. Yelling into the microphone, as a quick test, should trigger the relays. Setting the threshold potentiometer for a “97” setting will cause a decrease in sensitivity. A threshold setting of “83” will cause an increase in sensitivity.
Distance from the sound source is also a factor for triggering the relays. Acoustically, for a location, if you increase the radial distance twice, you will receive an approximate 6dB loss. This generally applies for free space sound travel not including reflective surfaces. A good, general acoustical outdoor, free-space sound travel, distancing rule.
Outdoor use. Operation in a large range of temperatures.
Moisture resistant microphone.
Two adjustable, independent relay triggering circuits.
Yellow and Red relay LED lights to indicate relay-1 and relay-2 triggered.
Steel, powder-coated chassis for long life operation. Chassis has two pieces: Face plate and back plate. The back-plate is fastened to the face plate with four 6-32 stainless steel screws.
Small, portable size.
Convenient, easy mounting screw holes on chassis face plate flange.
Easy sensitivity adjustments. Threshold alarm-1 and alarm-2 settings, P1 gain potentiometer, and practical distancing from a sound source.
Instrument weight: 1.5 Lbs.
Dimensions: 2” depth, (LED Lenses included), 4.25” x 5” faceplate, not including the mounting flange (.625” x 4.25”).
Wiring terminal connectors are screw-tighten for gauges 24 – 16.
Operational supply voltage : 12 – 24VDC
Operational current draw:
11mA - (with relays not triggered)
50mA – (with both relays triggered on, and a 24VDC supply)
These sound alarms can be used in hundreds of applications. Configure them to detect a certain decibel level and it triggers a powerful 5 amp signal to a 240v AC relay. Powerful enough to drive a 400 amp switcher, the possible applications are endless.
Our sound alarms have been used to detect the sound caused by pressure build-up in gas well-heads.
Detect when helicopters are landing on the roof and automatically close air vents to prevent fumes entering the building.
Monitor the sound of pump motors for an early warning when the motors become clogged.