I would like to hook up a PIR motion sensor like the one found here with a standard electric air mattress pump like the one found here. I'm pretty sure this is basic electronics stuff but I have zero experience. Any ideas on how to do it and what materials I might need? Any help would be greatly appreciated!
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2 Answers
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Many ways to do this BUT easiest for a beginner is probably a relay.
Complexity can be added as required :-).
You can also put airpump where relay coils is on diagram and drive it directly. See below for a good FET to use.
Output voltage from PIR is not known - you will need to advise this BUT this will almost certainly work.
MOSFET (shown as a IRF511 but see below) is an electronic switch that converts the PIR voltage output to a higher power level.
This is shown as 12V but relay can be any DC voltage that suits. Usually 5V or 6V or 12V are common.
The relay contacts act as a switch - connect them across where the switch is at present.
The STP62NS04Z MODFET is available at Digikey for 43 cents in 1's in stock.
If used in the circuit below it could be used to switch the airpump directly.
It is rated at 60Aand 33V so should probably be OK. That is a FAR higer current than the pump takes when running but fun things can occur at startup. MOSFET datasheet here
For a less painful ride you should advise
Airpump Voltage and power or current.
PIR output voltage and whether high on detect a(as assumed here) or low on detect or ...
Data sheet links for above would be a REALLY good idea.
Relay contact ratings have to match air-pump requirement.
If PIR output goes low on detect circuit would need to be very slightly more complex.
1N4001 diode MAY need uprating depending on pump current drain - which you are going to find out and tell us :-).
As above - pump motor COULD go where relay coils is and no relay is then needed. This does mean that PIR may be destroyed if things go wrong. Discuss.
answered Feb 1, 2012 at 12:26
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\$\begingroup\$ The Amazon page in the OP's link says that the PIR's output is open-collector! \$\endgroup\$– MikeJ-UKCommented Feb 1, 2012 at 12:36
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\$\begingroup\$ @MikeJ-UK - Thanks. So if a relay is used a NC contact will work. If motor is driven directly it needs a jellybean transistor inverter. \$\endgroup\$– Russell McMahon ♦Commented Feb 1, 2012 at 13:07
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\$\begingroup\$ Okay thanks Russell and MikeJ for the input so far! Just to clarify, I'd need the PIR sensor, a relay and the pump device? I also wanted to note that I could possibly use a battery-powered air pump. Not sure if that would help or hinder. Any links to relay devices or anything else would be terrific! \$\endgroup\$ Commented Feb 1, 2012 at 13:35
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\$\begingroup\$ @Peter Barnett - The details on the pump don't mention it's current requirements but I have a similar (HiGear) model which comes with a 1A mains adaptor so Russell's solution is more than adequate without the relay (with a PNP inverter as he mentions). You might need a pulse-stretcher if you need the pump to stay on for any length of time though. \$\endgroup\$– MikeJ-UKCommented Feb 1, 2012 at 13:53
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\$\begingroup\$ Okay - so if I'm understanding correctly, I will not need a relay because the air pump will have enough power through the mains adaptor? I'm not quite sure where the PNP inverter comes into play. How exactly is the inverter to be used? Basically I want the motion sensor to switch the air pump on whenever activated. There is no specific time length - I would just like it to switch on while there is movement and switch right off when it is still. Thanks again for the help! \$\endgroup\$ Commented Feb 1, 2012 at 17:08
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You could use a ready made device if you just need the one. It may be faster to order and less work than making your own. There are numerous devices to do the job.
Below is one example picked at random from a Google picture search.
Remember to add in a reliable oneway valve if you do not want the air to rush out when the pump stops turning.
http://www.amazon.com/SensorPlug-Motion-Activated-Electrical-Outlet/dp/B000A3CIUW
