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Forum Index : Electronics : Why is there a diode in thsi air pump?
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5106 |
I picked up a little air pump the other day. I didn't really need it, but it was cheap. Yes, I horde. Powered it up, and it went for about 5 seconds, then my inverter shut down with a fault. I'm off grid, everything runs of a Latronics 5kw inverter. I had a suspicion. I had my inverter shutdown like this once before, about 10 years ago when I was using a heat gun to strip paint. The heat gun was on a low setting, and it does this by putting a single diode in series with the heater element, effectively cutting the power in half. My inverter doesn't like to see a big load on one phase only, so goes into fault mode. A technician at Latronics confirmed to me this was a know problem with an older firmware version. Back to the air pump. I pulled it apart, and bingo, there's a diode in there. But why? I'm tempted to short it out and see how the pump runs. I guess it will be twice as fast, maybe overheat, not sure, so thought I would ask if anyone knew any more about these air pumps.   Glenn. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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phil99 Guru  Joined: 11/02/2018 Location: AustraliaPosts: 2407 |
My guess it is really a 110V model modified for 240V. If you have a variac or suitable transformer you could try it without the diode. |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1114 |
I have 1 of those, they don't run at all without the diode, had to repair it and it had aluminium wire that got damp and rotted. I think it is half speed with diode and one direction? cant confirm as its in bits somewhere Pretty sure there was a spring at the other end, The HF inverter ran one of these pumps for years no problems, but the inverter didn't run the heat gun on low.  Edited 2025-03-16 19:24 by Revlac Cheers Aaron Off The Grid |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5106 |
I'll do some experiments. Try shorting the diods, but I suspect as you said Revlac it wont run properly. I might also try a full wave bridge rectifier, so it will get 100 pulses a second instead of 50. That may be to fast, the armature is to heavy and it wont pump properly, but at least the inverter will be happy. Let you know how I go. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2407 |
Perhaps tape a temp. sensor on a field coil (assuming there is a way to get the wire out) before trying a full wave bridge rectifier. If it gets too hot some voltage reduction may be needed. |
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