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.
Some experiments with supply voltage showed the unit was more likely to latch up when initially powered with a lower voltage, but once it's running the unit will keep working until the AA cell gets down to less than 0.6V.
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:- www.bigclive.c...
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