AndyGadget
Senior Member
I've just bought a couple of small air pumps to use as part of my solar powered, Picaxe controlled, filter, top-up, aeration and circulation system for a small (2000 Litres - 440 Gallons) wildlife pond.
These are the ones - https://www.skycraftsurplus.com/12vdcdiaphragmairpump.aspx - Less than 3 quid apiece on eBay. Primarily used for blood pressure monitors and drinks dispensers.
Brushed motors so limited lifetime, but they feel solidly built and won't be running continuously and at 3 quid a throw, I'll keep a few spares.
All the specs I've seen say power consumption is 300mA, but mine both measure (checked on 2 meters) 60mA off-load, rising to 75mA when pushing a large quantity of air through an airstone (diffuser) in 2'6" of water.
The pump (only using one) will be driven from 12V via a ULN2803A and at full whack is pushing too much air. Rather than throttle the air-line I want to run this with PWM from the Picaxe.
I haven't tried this yet (need to make a couple of hardware mods on the board first) but what sort of frequency should I be looking at to get maximum efficiency?
Andy.
These are the ones - https://www.skycraftsurplus.com/12vdcdiaphragmairpump.aspx - Less than 3 quid apiece on eBay. Primarily used for blood pressure monitors and drinks dispensers.
Brushed motors so limited lifetime, but they feel solidly built and won't be running continuously and at 3 quid a throw, I'll keep a few spares.
All the specs I've seen say power consumption is 300mA, but mine both measure (checked on 2 meters) 60mA off-load, rising to 75mA when pushing a large quantity of air through an airstone (diffuser) in 2'6" of water.
The pump (only using one) will be driven from 12V via a ULN2803A and at full whack is pushing too much air. Rather than throttle the air-line I want to run this with PWM from the Picaxe.
I haven't tried this yet (need to make a couple of hardware mods on the board first) but what sort of frequency should I be looking at to get maximum efficiency?
Andy.
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