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I bought a few of these devices many decades ago and ended up wrecking them during my experiments.

It seemed like a good idea to source a NOS (New Old Stock) unit to reverse engineer.

It turns out to be quite sophisticated, although it does have a slight latch-up issue on some power-ups.

https://www.youtube.com/watch?v=spd7ZhZgumY

Files

1.5V powered Glade Wisp ultrasonic oil atomizer

A look at a surprisingly sophisticated air freshener that emits tiny puffs of aromatic oil to mask smells or add an aroma to your environment. This unit is notable for using a single AA cell to power a tiny ultrasonic disk that pulses every 8 seconds to atomise oil that is supplied via a wick. It does this 24/7, but still gives very good battery life. The blob IC seems to be an ASIC (Application Specific Integrated Circuit that may have three separate RC oscillators for programmable timing, plus some logic for allowing time delays to be set. There's a MOSFET and transformer based piezo drive circuit for boosting the voltage up, but also a separate trickle charged reservoir capacitor to allow high current pulses without affecting the rest of the circuitry or risking component damage if the circuit latches up. Interestingly I did manage to latch it up with the MOSFET jammed on during power cycling. Normally the circuit just draws a few milliamps to recharge after each pulse, but when locked up it drew about 16mA. Maybe that's why the product was discontinued. That and the relatively high manufacturing cost versus simpler mains powered aroma units. Subsequent tests hint that the two separate resistors may set the time-base and the aroma burst duration, with the chain of four resistors probably allowing fine tuning of the piezo drive frequency. The three capacitors will probably be the matching ones for each of those three timing circuits. If that is the case then it possibly makes this circuit hackable for driving alternative atomiser disks. It's interesting to note that there does seem to be a collectors market for air freshener units, in the same way people collect lights, fans, vacuums and many other electrical items. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random air fresheners for disassembly at:- https://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators

Comments

Anonymous

I'm starting to understand your interest in air "fresheners".

Mike Page

Great teardown, thanks Clive. The 560R guarantees no more than 6mA draw on the 3.3V rail, so it doesn't wobble about when the high power stuff happens (and upset timing). And the bandwidth of draw is smaller than the bandwidth of 3.3V regulation so happy days. It's interesting they've gone for a transformer plus another choke. I guess they couldn't figure a way to do both in the one component as is done with welding transformers.

Jason Greene

Clive, if you feature an item that is available online would it be possible to post the link here on Patreon? It would be a nice extra perk for us. We all know how it would go if you posted it publicly.

bigclive

If it's a very good item I usually add a link here as well as in the YouTube description.

Jason Greene

Good or not we still may want to experiment. Muahahaaaa