This week’s EYE ON NPI (video) is a topical one – here at Adafruit we’ve been supplying essential services and goods for engineers, makers, doctors, and students all working on designing products and techniques to help folks with COVID-19. This is an amazing time to see so many talented and driven folks around the world all putting their talents to work!
Part of that design work is to have the device alarm a caretaker that something went wrong. For example, if you are designing a pulse oximeter or heart rate detector, you’ll want to sound an alarm when the BPM or SpO2 dip below a safety threshold. You’ll also need an alarm when power is lost, say if someone accidentally unplugged the power cord. When building DIY and IoT projects, a simple 3V buzzer or piezo might be enough – to let you know when the plants need watering, or if there might be rain tomorrow – but this is not enough for an industrial or safety device, especially one being used in a loud environment.
The new CPS series of sirens from CUI is a nice and easy way to add a very loud alarm, and comes in a few different shapes, styles and output effects. They’re all about 100 dB, as loud as a jackhammer or motorcycle. Inside, they’re buzzer/piezos – but really large ones, that are driven by 12V DC. What I like about these is that you don’t need to generate the audio waveform from a microcontroller: they start warbling or beeping the moment power is applied. Why is this good? Well you probably have a nice speaker output system in your design, whether its a DAC, PWM or I2S output, and that’s good for nice harmonic tones, verbal alerts or even sound clips – all of those kinds of alarm designs are covered by standards like ISO IEC 60601-1-8. But what happens when you have a power failure or a software interlock failure? You may not be able to depend on your software system. These can be controlled or powered by solid-state technologies that don’t have a clock or software, as a backup alarm.
CUI Devices’ CPS series sirens utilize piezo technology with a built-in driving circuit to offer designers a range of variable tones and sounds, including hi-lo, warble, and more. The CPS models feature sound pressure levels (SPLs) up to 120 dB as well as through-hole, panel mount, and wire lead mounting styles. These piezo sirens can carry operating temperatures from -30°C to +85°C, making them well-suited for security systems, medical devices, harsh environments, and industrial applications.
- Piezo technology with built-in driving circuit
- SPLs up to 120 dB
- Multiple mounting configurations
- Hi-lo, warble, sweeping, one tone, and six tone offerings
- Operating temperatures: -30°C to +85°C
There’s a few in this series, from one that looks like a little horn, to an enclosed box. If we had to pick one to try out, we’d say the CPS-7560 (a.k.a 102-CPS-7560-110L450-ND) is the cutest one, with a panel mount style that evokes an arcade button. This design looks super easy to mount – you just need a round hole in your panel, and is unobtrusive.