Racal-Guardall 1980s PIR Sensor Teardown - Compared with Modern Equivalent

[@wajopek2679]

I used to install these as part of external security perimeter lighting systems. There was a wall mounted controller they connected to that powered them and activated the external flood lights.

[@mikeselectricstuff]

the white blocks are capacitors, not resistors

[@clone_enolc]

Can you speculate on why they would use two different types of capacitors? Cheers!

[@stephenbell9257]

@@clone_enolc The white capacitors are plastic film types which provide good accuracy and stability but are used for lower values, typically < 1uF, due to excessive cost and size for larger values. The black cylindrical ones are electrolytic capacitors which are used for lower cost and smaller size in larger values, at the expense of poor accuracy and stability.

[@davidandrews8566]

The LM324 is a quad op-amp package configured as 2 gain stages and a window comparator.

[@Graham_Langley]

Standard cct for a simple PIR back then. I used it in umpteen designs. [Later] I've looked up my traced ccts from around then and Racal liked a single op-amp window comparator using steering diodes. That would leave an op-amp free to do something else - trigger time mono say.

[@Graham_Langley]

Nearly right John. A pyrosensor as used here will have two elements connected back-to-back (inverse series or parallel) and arranged side-by-side. As they are a very high impedance source there's a JFET buffer in the can along with a bias resistor. The back-to-back connection of the elements nulls out ambient temperature so there's only an output when one sensor receives a different amount of IR radiation (around 10u wavelength) and so has a different temperature to the other. The faceted mirror or HDPE Fresnel lens generates a set of detection zones. The image of an object with a different temperature or emissivity (see later) from the background moving across a zone will pass over one element then the other, resulting in a + - or - + signal at the output of the sensor. This signal is amplified followed by a threshold detector. Why different temperature or emissivity? The sensor elements respond to the amount of IR energy they are receiving and this is set by the temperature and size of something in its field of view, and also by its emissivity, i.e. how well it radiates heat - think black heatsink vs. shiny polished one. (And before anyone asks, the emissivity of human skin at 10u is 0.97 regardless of colour.) I suspect the 'early LED' package is a photodiode or phototransistor as used old-style mice. I did a similar multi-head design to this around the same time for another company. On installation one head was chosen to be the best one to sense day/night and its photosensor was connected back to the controller.

[@Graham_Langley]

Wow - three weeks on and no one's contradicted me!

[@FatNormanCoathanger]

@@Graham_Langley . Well, i suppose any contradiction would have a battle with your ego.

[@Graham_Langley]

@@FatNormanCoathanger There's always one...

[@zeno2712]

I posted this comment a few days ago, but it didn't appear! Trying again. I worked for Racal Guardall from 1979 (when I graduated) to 1998 (when I left to work for a competitor, Ademco Microtech (which was later taken over by Honeywell)) and the RCL1 was designed by a colleague of mine, Jon McLean. The factory was in Newbridge on the outskirts of Edinburgh, next to Edinburgh Airport. The factory carried out R&D, procurement, manufacturing, etc all under one roof. I think the writing was on the wall when I left as the company was taken over by those simply interested in the bottom line and run by those who didn't understand engineering - it's too easy for accountants to say manufacturing had to be done in China or elsewhere, but the advantage of being one minute away from the production line can never be overestimated. I'm not sure when it finally closed but I think the last owners were Chubb and then Kidde. I designed several other PIR detectors for security systems there and I later was the UK Principal Expert on PIRs for the British Standards Institute when I was working for Honeywell in Glasgow. In terms of how these detectors work, Graham Langley has it right (see below), which is why no one has contradicted him! :-) The company started out as a defence company designing microwave products (on the same site). As Chris Anderson says, the company was founded by RAmond Brown and George CALder (so Ray-Cal) but it split and expanded over the years. Racal Security itself was started by John Stradling and others after a prototype microwave doppler detector was demonstrated on Tomorrow's World - possibly in the early 70s: I worked on their production line tuning microwave cavities during my Easter holidays in 1975 - and in their R&D lab before my final year in 1978. I was offered a job in R&D if I graduated so had a free and easy final year knowing I already had a job to go to. It's fascinating to see John's teardown of it - I suspect the instructions would have been packaged with the controller that came with it so you don't have the complete unit.

[@blubbspinat9363]

the modern one appears to be a very common item sold under various brand names. I used to have two of these on a solar powered garden shed because it can be easily modified to work on low voltage DC as low as 5V= the sensor module just has three pins: Ground, VCC and Signal. Signal gets pulled up to about VCC when something is detected. Just replace the relais bord with a MOS-FET or bipolar transistor and a small voltage regulator to match the output voltage of the mains powered board(might be 5V or 12V depending on the exact version) and that's it. Also, thanks for the video, it shows how these things have evolved over time, was pretty useful info all over!

[@FastAsFunk]

We had several of these exact same units installed on a house when we had an alarm fitted back in 1988. Although not linked to the alarm, they were used to trigger outdoor security lights in combination with GJD lighting controller units. Eventually all but one of the Racal units failed and were replaced with GJD Opal PIR units. I expect it was no coincidence that the only one that didn't fail was also the only one not directly subjected to the weather. Thanks for the memories John...!

[@obd6HsN]

That's interesting - I'm surprised that the potting didn't protect the electronics. I thought it looked pretty effective.

[@FastAsFunk]

@@obd6HsN I can't be sure what caused them to fail. They were replaced by the alarm installers they originally fitted them (PAL Security). We lived at that house 17 years give or take a few months and within a few years the Racal units were dead and replaced with the GJD Opals apart from the one that was under cover in a car port that lasted our full 17 year tenure...

[@richardbourne7360]

I think 8806 on one of the components possibly refers to the year and week that component was manufactured. Week 6 of 1988, making the unit around 30 years old.

[@Graham_Langley]

The unit's batch number 939 makes it even younger - week 39 of '89.

[@bigjd2k]

Used to have that system at my parents house, running for 40 years no problem!

[@memecoinmafia2732]

cool ..great to see the comparison from old to new !

[@steamhammer2k]

One of first jobs was with RACAL in Bracknell. BTW You pronounce the company name as RAY - CAL from the founders names RAmond Brown and George CALder Cunningham

[@NOWThatsRichy]

Racal became Vodafone in the late 80's.

[@TheEmbeddedHobbyist]

​@@NOWThatsRichy No Vodafone was just an spin off from Racal; Racal finally bit the dust when it was sold to Thomson-CSF which went on to become Thales in 2000. Note Racal also was part of the start up of the National Lottery in the UK.

[@zeno2712]

Oh. The first job I had in 1979 was to design the beam pattern for the chrome-plated mirror used in the RLC1S - it was originally designed for the IR771 PIR detector.

[@kevinrayment457]

As you compared the two types, it would be interesting to know if the 3 wire version can be used in a specific configuration to replace the 4 wire version. 4 of the one you stripped down are fitted on the back of my house and the last recently failed. They connect to a Racal Guardall RLC1 Light Control Unit indoors to select for sensor/night-time/permanent-on with a sliding adjustor. The permanent-on setting still switches them on, but the sensors no longer trigger the lights. I imagine the missing yellow (faded to white) wire may possibly be the darkness output and wondered if it was removed from newer PIRs because it is instead controlled on the sensor itself with a dial? Also does the new one operate with the same voltage?

[@rumbarumba1]

I used to work at the one in Newbridge soldering and adding components in 1995

[@mauriceupton1474]

Racal Guardall had a manufacturing plant in New Zealand too, 1987. They manufactured alot of alarm panels and gear or maybe they just assembled it. They had security gear in a lot of houses and banks and supermarkets. That was in that was in the day where you couldn't import made-up equipment you had to assemble it in New Zealand otherwise you couldn't import it. Certain people held import licences and if you had one of those, they were like gold. All changed now.

[@uwepolifka4583]

Oh, interesting Information. I just found a package of 9 new Racal Gardall PCB with the mirror in my stock. It is Model IR745/2 from aprox. 1990.

[@chriholt]

Seeing the Racal logo reminded me of Racal Vadec modems from *many* years ago!

[@JoseighBlogs]

Not being an electrician I nevertheless found John's hands-on deconstruction and ongoing pleasant monotonal soporific patter unscrewing, prizing open, scraping "crud" from the device fascinating ~ as though he was a sci-fi archaeologist called in to examine a recently discovered 'otherworldly thing'. The stuff of potential scary sci-fi movies surely? Wonderful!

[@Brian_Of_Melbourne]

Thanks for showing us the part number of the pyrolitic sensor, and the date code on the earlier sensor - 8825 (late June) glimpsed at 20:45.

[@aquahits5674]

Hi John just wanted to ask you a question if you had reversed polarity on appliances would pat tester pick the the fault

[@jwflame]

Unlikely, and for most items it won't matter, they will still work as intended. It does matter where an appliance has a single pole power switch, as that should always be in the line - reversed polarity would put that in the neutral which would leave most of the appliance live even when switched off.

[@michaelrose5085]

Great videos. I have a question please. Inhave purchased a steinel sensor led light. But have been told you cant override it with the on off action of the light switch stienel have told me the following. You can put a 2 gang switch in, 3 way rocker switch or a IP rated outside switch, as long as the switch puts live in the live out terminal it will override the unit. How would i wire this i am confused..please help as need to have the option of sensor and permanently on when in the garden.

[@jwflame]

kzbin.info/www/bejne/qWGqY3ekfpumpqM

[@michaelrose5085]

Thanks. The light I bought has a sensor but pre wired so i connect wires from swtich and the unit clips in. Does this mean I have to wire a new sensor

[@trinityadam]

haha I Love it and your new word GUNK about 10:30 minutes in the video. You have a good Character. Never the less that would been a Good Motion Sensor back in the 70's era...

[@tonipeters-looks-at]

As some have said, it is a PIR, BUT it is for external lighting, NOT an intruder alarm. Black + Red were 12v the green was signal, the yellow was for the daylight sensor, so the lights would not come on during daylight. Racal were very good at making PIRs, so they ventured into this thing for external lighting, they were a good idea, but never lasted long, the first versions filled with rain. Its NOT a fair comparison, as the Racal unit was 12v and was wired in 4 core alarm cable back to its "control unit" the black one is mains and switches directly.

[@zeno2712]

Thanks! I designed several of their PIRs! 🙂

[@Abbadon2001]

Surprised the metalising was in such good nick, often it fails in less time on similar vintage items?

[@Mike_5]

They refused to provide instructions with these to prevent unauthorised people from installing them

[@KurtRichterCISSP]

Don't want too many people finding other uses for these! They'd buy them all up! (Company no longer exists)

[@MUHAMMADYAWARIFRAHEEM]

Very nice video

[@matthewbeddow3278]

Thank you John for the video & jolly interesting it was. Unusual for the newer, I'd imagine, a made in china product at least attempting some form of isolation between the high and low voltage sides. Interesting how similar the circuitry is between the new and old.

[@samuelfellows6923]

I assume - the first older sensor was for a burglar-alarm system, and the second more modern one for turning a outside light on

[@chrismaclellan7324]

I remember visiting the Racal factory just outside Edinburgh in the early 90’s where they made these sensors. The boards were set at an angle in their tray before being encapsulated in UV cured resin.

[@zeno2712]

I was working there at that time. What were you visiting for?

[@chrismaclellan7324]

@@zeno2712 We manufactured a uv light source with a light guide angled to get under the sensor.

[@epakai]

Unfortunate thumbnail. The red bar at the bottom makes the video look already watched in the subscription feed.

[@BM-jy6cb]

Wow. That's interesting the modern one is still using was essentially the same circuit with a simple opamp. I was expecting a dedicated PIR processing IC with very few external components. Even though the new one is a cheapie, the advances in design for manufacturing really stand out - and of course, taste in aesthetic design 🙂

[@karlosh9286]

yeah , me too. I was expecting a much higher level of integraton.

[@crazygeorgelincoln]

Been a while, hope all is ok.

[@nickhubbard3671]

Nat Semi quad op amp LM324N - 8806 - 1988 week 6 Not so old!

[@Graham_Langley]

The unit's batch number is even later. 939 = week 39 of '89.

[@markevans2294]

Also 8825 on the pyroelectric sensor and 2388 on the transistor.

[@randacnam7321]

@@markevans2294 It's a BC238B, so 238B not 2388. TO-92 package devices typically don't have date codes in the markings

[@burzheru]

well. no more warranty for you Mr. Ward :p

[@cjmillsnun]

The date code on the chip will be week 6 1988, not June 88

[@alunroberts1439]

The ceramic resistors are capacitors

[@zeno2712]

Yes, they are film capacitors.

[@lordmuntague]

I can't help being a bit baffled by that colour changing cable. At first I thought it was actually white and had yellowed at the end, since that was more exposed to the outside. Having seen the gel stuff however, I'm wondering if that has actually decayed and given off some substance that bleached the wire. Those filling compounds are usually far tougher than that, which suggests it had deteriorated considerably. Very odd...

[@tinytonymaloney7832]

Wasn't Racal part of the very early Vodafone company back in the 1980s

[@jwflame]

Yes, it was called Racal Vodafone originally.

[@tinytonymaloney7832]

@@jwflame I guess I'm showing my age a bit, the actual color and design of that PIR reminds me of them old View Master things, now that's going back 😉

[@andybarnard4575]

Wrong way round! Project Vodafone was a tiny part of RACAL..... started with a dozen or so employees. I believe they have grown since then and outlived their parent.

[@tinytonymaloney7832]

@@andybarnard4575 Cor, I wish I had a grand to invest in some shares then, I think my bank balance would be somewhat substantial now 😋

[@Graham_Langley]

@nick Ellingham My mother was a freelance comptometer operator and used to do work for them.

[@mrsecurity]

I’ve got the controller for this system

[@zeno2712]

It's not still in use, is it?

[@mrsecurity]

@@zeno2712 no it’s brand new in box never fitted

[@barrieshepherd7694]

The Racal unit looks like it was intended for use with intruder alarms so would be powered from the alarm control unit. Hence the lack of light sensor and no adjustments. The LED would be for 'walk testing'. The output would probably have been looped for tamper protection or one wire for tamper and one for alarm.

[@tonipeters-looks-at]

Sorry it was for external lighting system made by Racal.

[@Graham_Langley]

@@tonipeters-looks-at And its got a light sensor by the look of it.

[@Azkar701]

Hi J W, this is Az and I'm you're KZbin follower. I'm really sorry to contact you here because I couldn't contact you on KZbin, my Apologies. If I may ask you to please do a video on outdoor flood lights with photocell and timer switche. I have seen your all video and all your videos highly informative, if you could do the video drawing a diagram. Much appreciated. Regards Az

[@tonysheerness2427]

In 35 years they never improved on the design, which says a lot for the original.

[@DjResR]

There are some quite compact PIR's available also like the ones attached to the LED floodlights, the one in the video looks like from 2000's._

[@Xclub40X]

A rascal guardall PIR Yeah, don't be a rascal, keep watching JW.....