Making a PIR Sensor Less Sensitive

Sponsored by JLCPCB ($2 for 10 Boards): jlcpcb.com
This PIR sensor is too sensitive - it keeps turning on even when there's nobody about. A few resistors added to the circuit have reduced the sensitivity.

[@steveng5503]

Insulation tape on the facets of the fresnel lens to block off unwanted areas does the trick. Alarm Engineer trick.

[@marvintpandroid2213]

Exactly what I was going to say

[@bridgendesar]

Would have been a short video!

[@joinedupjon]

did that at my dads to prevent nuisance triggering of a lamp with built in PIR - worked but has reduced the amount of light entering the ambient LDR which is behind the same lens... just means it starts switching a bit earlier in the evening than it should.

[@Graham_Langley]

Polyester tape, AKA Scotch 'Invisible' tape or probably any write-on tape, works fine and is less obvious...

[@steveng5503]

Yeah, there’s gonna be lots of variables I guess. It’s down to the individual and the type of sensor. Trial and error comes to mind.

[@GoScada]

Please use the wonderful oscilloscope you have and probe the two amplifier stages while tinkering with the resistors

[@bokkenka]

Walk down completely black steps and then get a light in the face... "Job done. Perfect. Cheerio."

[@DavidKirwanirl]

Laughed. Great example of why its never ok to disable youtube comments.. you'd miss out on gems!

[@maicod]

love your comment.

[@pintokitkat]

Wouldn't putting black tape over the inside of most of the plastic lens have worked? Not an electronic fix, but perhaps an easier one.

[@airwavested]

Yes, but where's the fun in that!? :-)

[@FindLiberty]

@@airwavested true enough. Gud die mite!

[@jamhough22]

Was going to suggest this as i fit alarms for a living and often you get cards with the sensors to blank of areas on the lens you don’t want to pick up movement.

[@ZlayaCo6aka]

PIR sensor outputs are typically pulses, so those opamps are also acting as integrators. Think: you're affecting the high frequency rolloff by changing the feedback resistors without also changing the paralleled caps. "Sensitivity" is essentially a function of the RC time constants.

[@thomasvnl]

Random Friendly Spider @ 10:10 - 10:15 :')

[@AttitudeGames]

Yep, they popped over to inspect the work LOL

[@WaltonPete]

The lens is an integral part of the detector so testing without it is unlikely to yield reliable results. As such, it's possible to reduce the coverage of the detector by putting electrical tape on the lens (either inside or out) to reduce unwanted trigger events.

[@gelisob]

Hot glue is super easy to remove. Thats one reason why i use it almost in every project now. Just shoot a bit of alcohol between it and it comes clean off. You could even get it off paper without tearing it, give it a try. And then when modifications/work is done, it is again easy to reapply it. Isopropyl alcohol in a can, used for cleaning electronics, for example.

[@darkknight145]

If you are thinking of running thin wires to charge the battery: Why not get rid of the battery altogether and perhaps use a super cap bank to take the load when light is on, cheaper than a battery in the long run?

[@JulianIlett]

You read my mind :)

For the remote battery you could try to boost the voltage, so you reduce the voltage drop on the long cable. Of course, you will have losses in you DC-DC converters, but hopefully it will not be as high as the cable alone.

[@JulianIlett]

Ah but when very little current is flowing, there will be very little voltage drop.

[@locouk]

Could you put a semi IR transparent cover over the sensor, something like a bit of plastic cut from a takeaway food carton had this not worked?

[@chilllytube]

You said the pin numbers were wrong, but you still put the res between 1 & 3. Or did I get that wrong?

[@publicmail2]

That type of lens is made for indoor ceiling, you need to mask lens with tape.

[@FindLiberty]

Exactly

[@AdrianTechWizard]

Julian Ilett locks himself out while filming PIR light!

[@oldmanhuppiedos]

What also helps is masking surfaces with tape. Or tension a foil over the hood.

[@FindLiberty]

Yes oma. Reduce and/or block the IR optically. Make a map of the optical path by using flashlight and close-up video recording of a tiny white screen (at the sensor distance) while on bench. Use this to design a tube, curtin or partial shutter INSIDE the lense to mask the IR multiple *view(s)* _of the road_ from making *their* way to the PIR sensor! Select a clear tape or plastic that blocks the IR, or just use some aluminum foil and lots of hot snot glue.

[@sparkyprojects]

If you need more PIR's, take a look at security types (intruder alarms) they usually run on 12v, but also have sensitivity control Also they have blanking shields so you can reduce sensitivity of any area of the sensor (so your dog doesn't trigger it for instance)

[@tibib4029]

Hola ! Es posible modificar una lampara solar de 2 modos a 3 modos ( para que se quede medio encendida de noche) ???

[@jamhough22]

I too have found data-sheets wrong in the application guide, showing electrolytic caps the wrong way round!

[@Graham_Langley]

I get the impression the data sheet values in the amplifier chain were arrived at by random fiddling - the upper amp has less than a third the passband of the first for a start. I always used two identical stages.

[@ElmerFuddGun]

10:05 - Did you see it?!?! LOL... oh my!

[@piconano]

That spider photo-bombed real nicely!

[@ElmerFuddGun]

​@@piconano - Did you notice at the time or after my comment? I bet it is still wondering around in Julian's lab since he didn't notice it at the time. Those daddy long-legs move FAST!

[@salutoitoi]

Took me some time to see it (even in 0.25x speed) nice

[@JulianIlett]

Ah, Pholcidae - cellar spiders. The house is full of them (in the loft mainly) - they don't bother me at all. I think they keep the larger black spiders in check, because we get very few of them :)

[@massimookissed1023]

@@JulianIlett , yep. They have weak, spindly legs, short fangs, and weak venom, ~ and they easily defeat much bigger stronger spiders. They use their long front legs to wrap silk around their victims from a distance.

[@manuakasam]

I was watching calm and interested and then a spider walks across the board. As an arachnophobic dude I can't fathom how one couldn't even notice it. I'm scared, can't watch further!

[@hieroben]

That light is conveniently placed. It's shining any burglar directly in his face, making him blind immediately…

[@pleasecho2]

I see Product Placement for the TS-`100

[@Error42_]

For some strange reason, with that title I felt there should have been a wooden mallet in your thumbnail.

[@Anvilshock]

Leave it out for a couple more weeks in the British weather, it'll quiet down alright. Permanently.

[@Garry.Anderson]

interesting point regarding a remote battery...ive considered the same in the past as my solar/batteries is in my workshop some distance from my house where it would be nice to use some of the power generated however to to volt drop i've shied away from it.

[@JulianIlett]

Thanks Garry - I'm thinking the volt drop will be tiny when the current flow is tiny, so both batteries should reach the same voltage eventually.

[@jp040759]

Have you had good success with hot glue sealing out water on outdoor electronics. I was thinking of doing the same thing with Halloween decorations for outside use. Please advise. Thanx.

[@joinedupjon]

Halloween was 2 weeks ago did you see PWM autopsy kzbin.info/www/bejne/lYqqnYWhdtemr6M though that took a few years to get in. fwiw John Ward was showing a flexible sealant on his latest video - quite pricey tho. The Dri-box works well and it's what I'd want to use on mains powered xmas decorations outside

[@matthewmiller6068]

Wish I had that problem... can't get out PIR to turn on the light until you are tripping trying to find the sidewalk.

[@hamzaqadir9589]

what is the sensitivity of this sensor??? minimum and maximum...

[@benwinkel]

Job very well done! I liked that!

[@joinedupjon]

looks nice now but check that black sharpie in a week or two - TBH I think it'll degrade quite quickly under the sun, even the weak british sun in november.

[@MasterIvo]

I still want a pir sensor for stairway lights.

[@TheChipmunk2008]

Woodlice are not disgusting, they're just differently gustatory :)

[@lezbriddon]

touch sensor with greasy finger, bam, no more sensitivity.....

[@jonshouse1]

This is the wrong PIR for the application. You need a 180 or 120 degree beam rather than the omni sensor you are using.

[@james-5560]

Lucky you didn't get plastic lice. I saw you moonlighting on canal boat channels! (picture only). Yes some of us like electronics and canal boats :)

[@richardharries5551]

Glue a toilet roll onto the lens, legs passing would trigger but not cars/birds/leaves or if you're really rich a six inch length of plastic pipe being more waterproof....necessity is the mother of invention but an Engineer is usually the father....

[@ElmerFuddGun]

_Silvan Chip Electronics Tech Co. Ltd._ isn't exactly good at proof reading... *three* pin names are different on the pin description list at 5:49 vs. the example schematic at 5:49. LOL...

[@jonstorey3985]

Hi.i am sick of the energy companies charging far too much. I was wanting to go for pannals like you have. But I'm on a small budget due to been disabled. Could you please give some advice on a cheap but with some quality. Lol. Thanks jon

[@joinedupjon]

Hi jon, IMO you're looking at pretty high startup costs and long payback periods for enough solar electricity to make a difference to your bills. probably more effective to hold your nose and stay with grid electricity and concentrate on insulation and energy efficiency first (for which grants may be available) if you haven't already.

[@jonstorey3985]

@@joinedupjon I thought about more putting things together myself. As I do understand electronics. Iv had insulation done to my property and have a stove fitted. As the only gas I use is central heating. But the stove heats the house. A friend does my washing and I have a bath there. I cook on bottled camping gas. I only watch thing on my tablet, 2 energy saving light bulbs are on all the time in the dark park of the house and what ever room I'm in on a night and a fridge freezer. Not a lot of energy used. But my energy company are taking £111 from my account and they want more. I am disabled on a low income. I just can't afford there prices. Iv tried to leave them. I'm in a contract and can't afford there leaving fee. Plus I gave them meter readings. They said the readings are to for the computer to accept. They said the manager will be ringing me about the low readings. Nobody did. But I was sent a letter saying they was putting my direct debit payments up.

[@joinedupjon]

@@@jonstorey3985 I've completely stopped letting utilities charge me by direct debit because of the unpleasant and unexpected shocks from their billing computers - only for people who tell me up front what they're going to take and when now e.g. council tax. the privatised money grabbers can shove their direct debit discount - I woldn't be surprised if they're overestimating (i.e. overcharging) on demand to flatter the budget at accountant critical times of year in order to trigger the directors bonuses. Maybe brain surgeons and investment bankers can afford to give the French government an interest free loan of a few hundred quid everytime they decide to have a bit of trouble averaging out my usage... but I'm not in that category. Fairly obvious point is that unless you disconnect from the grid entirely you're still going to get gouged for the standing charge, but having a solar system reliable enough to let you live your normal lifestyle without worrying about running out is going to be IMO unrealistically pricey for someone on a low budget. julians reviewed chinese solar panels from banggood at around £1/watt in the 100s of watts range and new 12V 'leisure' batteries are £70-£100 / 100Ah If the lights you leave on the most are still CFL types I'd suggest swapping them out for poundland 3W LEDs even before they fail

[@MrBrymstond]

Put a shield up so the lights don't set it off.

[@davidhoekje7842]

lol I was thinking of a bit of translucent plastic over the lens

[@xbipins]

why dont you try a board that uses a EG4002 chip, works much better and lot less components required plus a lot easier to control sensitivity

[@xbipins]

i recently designed a PIR motion sensor board and during that time i tried the EG4002 but having bought a Panasonic digital output PIR sensor i went with a 74HC123 timer chip. Installed a few in a building and they work flawless

[@bridgendesar]

Use a second detector to create an "AND" circuit trigger

[@JulianIlett]

I like your thinking :)

[@bridgendesar]

@@JulianIlett I should have said an AND "GATE" ;)

[@electronic7979]

👍👍

[@johnf-no3kb]

With respect. Wouldn`t it have been a lot easier just to buy a pir with a sensitivity control ?? they`re about £8. 🙂

[@xanataph]

I'm going to reverse engineer the "mask the lens comments"...! lol At the historic railway station that I volunteer at there is an alarm PIR module wired as door announcer that I installed a couple of years ago. It is connected to a nasty shrill beeper that everyone complains about. Although I must admit I do enjoy the way it startles the uninitiated. ;) It was way too sensitive so I reduced the sensitivity by masking it off with a piece of card. But now having seen this I might do away with that and look at gain reduction. It's a fairly old PIR so it might use a different chip, but I assume it would be a similar circuit.

[@TheRealThisIsAlex]

!!! SPIDER AT 10:12 !!!

[@RabeaHussain]

Nice

[@dalenassar9152]

...a thin coat of white candle wax on lens...