Help with an alarm obsessed boy's project please!

My son aged 11 has been given an unwanted (probably broken) Texecom Exodus (4 wire) sensor and an Apollo integrated base sounder. He is alarm obsessed and spends hours watching Youtube videos of alarm tests! He spent the entire day yesterday fiddling with bits of wire and a 12v transformer and to everyone's amazement, he got the Exodus to show two red LEDs when he pressed the test button.

He wants to try to get the integrated base sounder to sound its alarm and deafen us all. Can anybody please help?

Is it possible to get the Exodus to talk to the base unit and make it sound, using only a 12v transformer and some bits of cable?

The Exodus has: 12v, latch, negative/common, common, 0v and these are labelled A to F.

The base sounder has: earth, loop 1, loop 2, R-, R+. Also, what is the purpose of the removable tab with little breakout bobbles on it?

Why, when we test for voltage with a standard voltmeter set at 12v, can we not get any reading off the transformer, yet it still powers the Christmas lights?

Please tell us if you think there's any hope of getting this thing to work, he will not believe us because we are not electricians (as I'm sure you can tell) and this obsession is killing us!

I dont do fire, but, i dont think those are compatable.

I'm sure someone will confirm this soon

Not sure what type of transformer you are using. If it's just a bare wire wound transformer from an alarm panel, then it will probably be outputting AC voltage. The panel rectifies the AC voltage to DC with a bridge rectifier circuit (4 power diodes). Make sure you have your meter set to Volts AC when reading the transformer output and DC when reading any panel outputs.

If it's a power supply you are using and not just a simple transformer, then it may be that it requires a load on the output in order to supply a voltage.

I've never used Texecom panels, so can't help you with that. Sure someone else will step in though!

Be sure to keep him supervised if he's working near exposed mains voltages at the primary side of the transformer. As a youngster, I remember getting mains shocks from the age of 6 while tinkering with electrical and electronic circuits. Ouch! Memories of trying to hide my burnt fingers...

Cheers.

It sounds like they are using a plug in tranformer. You would need to make sure it can output 12v DC.

The sounder you describe is more than likely 24v DC, the bobbles you descirbe being the address settings for the detector associated with the base. It sounds like a a loop powered sounder too which will not simply sound when you apply a voltage, it needs to communicate with a fire alarm panel.

Thanks! Yes, it's a plug-in 12v transformer for some Christmas lights and yes, I've told him I think the sounder will need to communicate with a panel.

He is also very well educated on the dangers of mains voltage.

Have to agree with the above, probs an addressable base.

Also if you fire 24vdc ascross pos and neg but reversed it will probably sound. If you get my drift pos to neg neg to pos.

Good work from the little chap, but please please please have anything he "plays" with proteced by a RcD and if possible supervise him.
Too many die from not taking the correct precautions.

Thanks all!

Want to give him a job?

Well he seems more clued up than most muppets on here.
Wait till he is a bit older, employment laws for minors are complicated.

A soldering iron and something like

http://www.maplin.co.uk/Module.aspx?ModuleNo=219998

might be welcomed for Xmas.

Or give him a pressure mat, a loud bell. A latching relay. And of course a PSU.
Frighten the life out on my Mum when she opened the wardrobe in my room!
I was 11 when I did that

RigidRaider,
I can't tell you about the Texecom Exodus 4 wire sensor, but .......I can tell you about the Apollo integrated base sounder, as I've just started to read up on Apollo stuff for an alarm installation.

Although you don't say which range the Apollo sensor is from, it IS one of the networked ones by the connections you name and the tag with the 'bobbles' on. L1 & L2 would connect this to the alarm network which carries both data and power over the same pair of wires. The tag with the bobbles on determines which address the sensor is present at on the network. The missing bobbles determining the specific address, and it lives on the back plate so the address is associated with a physical position not a particular sensor, which maybe swapped for another in the future.

As this sounder responds to network data from a fire panel, and the data is probably (i would hope!) check-summed, and its electrical/electronic design would (should!) in theory make it highly resistant to electrical disturbances, I would of thought it's highly unlikely that you'd be able to gets its sounder to trigger by 'mistake'. If you can I would question its design.

-clears throat- What your son REALLY needs....... but you might dispute this for fear of loosing your sanity, is a conventional alarm sounder which, when it's powered up, or triggered by seperate wires, will sound for him. I can't make any recommendations of make/model as I'm new to alarms and only interested in the networkable stuff, but hopefully this forum should be full of folks who will.

On the subject of christmas tree power supplies.....

Whilst these power supplies often carry various approval markings, in reality they are often poor quality inside. Sometimes dry soldered joints, full of hot melt glue like adhesives etc etc. It goes with the territory I'm afraid, cheap tat made down to a price. And it also runs the risk of being one of the many dodgy far eastern built electrical goods which escapes the UK's inspection bodies.

Can I make a recommendation here, as your son is so enthusiastic about experimenting, of a way to go with this?

Get him something called a bench power supply. These plug into the mains and then provide a variable voltage/s out, usually upto about 30v and currents commonly upto about 2 Amps. The important thing is though that if you stick to a good make (eg Hewlett Packard or Thurlby Thandar + others) then the safety will be much better and they're also built to take the abuse, especially being shorted out on a regular basis. Ebay is a good source for them and at a guess maybe about £50-£80 2nd hand. Just the same kind of thing they have on the lab bench in schools. Often they have analogue or digital meters on the front for voltage & current and this will help educate him as to the relationship between the two. But limit him to about 30 volts.

They also produce a DC (for that read: stable and non varying with time) voltage which is much more use to him for experimenting than AC is.

I don't know if £50-£80 ish is too much but I do feel that there's something much more than money at stake here; There's a little lad who's enthusiastic about stuff which might so easily lead to a future career. Too many kids these days are sat in front of computers and are not being creative with hands on things. If interest wanes you could always resell it. If you need it inspecting and checking out before the little fella gets it I'd be willing to do that for you.

It takes more componentry to produce a DC voltage from AC mains than to produce a lower AC voltage which simply requires a transformer. So I'm guessing your xmas tree light transformer is outputting 12v AC (for that read: varying - sinusoidally and at a frequency of 50Hz) and hence the reason why it won't read anything on a DC voltmeter.

@Alarm,

I roared laughing at your post when you said about you with the pressure mat and your mum when you were aged 11. And my mum thought it was just me at that age! Poor girl was a nervous wreck at one point. Most of the doors in my room had reed contacts on them too wired to bells.

But ....Jeeeez you must of been posh to of had a REAL pressure mat... lol...I had to make my own from foam and tin foil.

I bet loads of careers start in that way. God bless bells and pressure mats.

Wow! Thanks Peet, what a useful and enthusiastic post. I will certainly look around for a bench power supply. Not sure at this stage whether we want to encourage his interest in alarms because it's well into the realms of obsession rather than just interest! A couple of weeks ago he had a safety demo at school and came home demanding that we buy new smoke alarms for the house, which he now tests regularly, to the dismay of the rest of his family!

I have just installed an evacuated tube solar panel on the roof but he's barely interested in that at all.

Whereabouts in Lancs are you?

Hi Raider

How good is your son's knowledge of electrics. While "specialising" in alarms is interesting ( although the noise might annoy his nearest and dearest ) does he have a good understanding of basic electrics that make things work.

My career in electronics started at aged 6 ( well the seeds were planted ) when my parent bought me a Junior Electricians kit to keep me occupied when in bed with measles or something. Prior to that I had been dis-mantling and re-assembling various items like the two way bayonet adaptor that plugged in the lamp holder to allow the electric iron to be plugged in as well as having the lamp without properly understanding the flow of electrons etc etc.

The Junior Electricians kit had batteries, lamps, switches and other things from which I learnt the basics of an electrical circuit. Later I "progressed" to more complex things like telephones built using parts from the local army surplus shop.

I agree with Peet about a bench power supply. It is a sound investment when considering the price of batteries.

http://www.jprelec.co.uk/store.asp/c=1551/LCD-30V-Dual-meter-PSU

They also do bench meters and other experimental items.

http://www.jprelec.co.uk/store.asp/c=1059/Educational-Bench-Meters

I too built my own pressure pad.

Memories come back.

My first through beam detector was home made using a glass encapsulated transistor with the light proof paint removed to make it a photo sensitive device. With paint it was an OC71 transistor, without paint it was an OCP71 and cost four times as much. Later the OC71 was manufactured with opaque gell inside the glass.

Peet, not posh.
Father worked for a brief while for Banham Alarms.
I was given bits and pieces to "keep me quiet" being told "Work that out".
Loved it

@RigidRaider
"I have just installed an evacuated tube solar panel on the roof but he's barely interested in that at all."
A lot of people still dismiss solar energy in the UK but its well worth looking at. The PV stuff is coming along but using solar to heat water has been very viable for a long time now. Heatpipes lend themselves to this very well. I have a friend who has designed and made his own system largely out of materials deemed scrap by others and now doesn't pay much to heat his water 7 months out of the year.

@BenardGreen
"How good is your son's knowledge of electrics. While "specialising" in alarms is interesting ( although the noise might annoy his nearest and dearest ) does he have a good understanding of basic electrics that make things work."

I quite agree, how wide is it? It's about seeing where that natural interest & sparkle lies, and then nuturing it.

Ah yes..(anorak on)..the 0C71. A transistor old enough for it to pull its nomenclature from valves. 0 = no heater, & C = triode configuration.
Fascinating isn't it, that there's common ground in the early days of our messings about with pressure pads and scrap kit. In a way, a child apprenticeship, and how important it was.

@Alarm
"Father worked for a brief while for Banham Alarms. I was given bits and pieces to "keep me quiet" being told "Work that out"."

lol yes, I remember 'work that out' or something similar and my father worked for the Norweb leccy board before it was gobbled up and then finally became part of UU. I used to get scrap light switches and torch bulbs and batteries.