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I too am a fan of the squirrel cage fan, and have collected a lot over the years. One excellent location to source them for 'reuse' are photocopiers. Old anal

I too am a fan of the squirrel cage fan, and have collected a lot over the years. One excellent location to source them for 'reuse' are photocopiers. Old analog copiers can have as many as 4 fans while newer digital ones seem to have 2-3 depending on size/capacity. Mostly DC too, but I have also come across some big A/C fans. They almost always are designed for higher voltages (i.e. 20+VDC) so when combined with a common 12VDC power source it's already been stepped down. (source: used to work for a photocopier company, and when people bought newer units, we would pickup the old units and usually junk them.)

Kadin 4y ago
Old furnaces nearly always have big-ish squirrel cage blowers in them, and many are replaced before the fan motors fail for various reasons. In my area they are a reasonably frequent sight by the side of the road on bulk garbage day. If you get there before the scrap metal guys do, you could easily nab a blower. They're typically 120V single-speed devices, although some newer ones may have variable-speed fans. Not 100% sure how most of them vary the speed; my bet is that they just have some capacitors switched inline with the fan motor to add reactance to the circuit and slow it down. (That would probably be how I would slow down a single-speed one to make it quieter, at any rate.) There are a lot of projects online that you can find, showing how to build fairly big workshop air cleaners with a furnace blower and some cheap plywood/MDF/whatever. Basically you just build a 5-sided box around the blower with a hole for the outgoing air, and then mount a furnace filter on the open face of the box.