Old 1.5V fan based aroma unit teardown with schematic

I bought one of these a VERY long time ago, but recently saw a used one on eBay and bought it so we could explore it further. They still sell these on eBay, but they command a high price due to seemingly being obsolete stock.

The unit is powered by a single 1.5V D-cell, which makes me think the control chip is a dedicated unit for this application. It appears to have a simple RC oscillator and binary counter, with a bit of logic to provide a fixed 1 in 4 fan cycle. Lowering the value of the resistor did result in a change in the cycle speed.

There's a possibility that this chip was originally intended for the aroma units in public restrooms, but modern ones vary the fan duration according to the age of the aroma cartridge. (Short bursts initially, getting longer over time as the scent weakens.)

Interesting circuitry though. I may refill the scent bottle with a standard heated wick refill to see how well it disperses.


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