View Full Version : Electronics project

8th Nov 2011, 06:10
Morning all.

My middle boy is 7 this weekend, and he's got four friends coming round to do boy stuff for a few hours to help him celebrate.

I thought it would be good if I could come up with a small electronics project they could do and all have something to take away with them. Build a basic circuit with a switch and some bulbs or perhaps a buzzer/siren.

Can anyone recommend something that I could do failry easily with these guys, or a site where I could get some ideas?

It'll keep me from fretting about my lack of progress in the Volvo Ocean Race Game!!

Many thanks,


Arm out the window
8th Nov 2011, 07:07
What about one of these?

Redirect Notice (

8th Nov 2011, 07:14
When I was seven I got to build a crystal radio. Which, when attached to my metal bedframe as an aerial, enabled me to listen to Radio Luxemburg under the blankets at night. Magic. :ok:

Loose rivets
8th Nov 2011, 07:52
One of my favorites. The youngest, planning to take over the world.

Loose rivets
8th Nov 2011, 08:09
Oh, my...this has got me going again.

I had one of these when I was about 12. Only difference was it was sparkling new - straight out of military surplus that is.
Middle-right is best picture.

Receiver Type 87 R1132A Receiver-C MILITARY U.K. different m (

It looked so grand then. Rather modest bit of kit now. Had to make a full PSU for it - and rewind the coils. The dial mechanism was supremely made.

30/= 1.50 to you youngsters.

I've recently sold dozens of meter movements for the old AVO valve tester VCM 163. I used to buy things like that just cos they were there. 30 years later someone recognized them, and they're going around the world. The point? Oh, yes. While I was testing them, I drifted back into a fluffy warm state of being interested in these things. I miss having a hobby shop in the UK. One is just born like this - turned all the lights off in a Colchester library when I was about 4. Just thought I'd found heaven when I crawled to the fuse panel.

8th Nov 2011, 09:31
One of the best toys I ever had was a electronics construction set
Lots of components and diagrams to make things . You could even make a low power morse transmitter . Briiliant , dont know whether such things still exist

8th Nov 2011, 09:46
I've just been looking at Meccano sets, might be something there. ;)

Just a spotter
8th Nov 2011, 10:52
That brings back memories!

At the risk of falling foul of the board rules on posting links to 'commercial' sites; Maplin's have a range of electronics kits of varing complexity and 'coolness', also listed on their site.

A quick puruse of interwebs via your favourite seach engine for "electronics kits" will yeild plenty of results.


8th Nov 2011, 11:47
Lots of good ideas on THIS ( web site, made one or two myself and pinched some of the ideas for other projects.


8th Nov 2011, 12:06
Maplin used to sell lots of inexpensive kits. They're on-line if you don't have a store near you.

Amazing Advanced Connect N Learn Electronics Kit : Beginners Projects : Maplin (

I plan to do the same thing will my eldest soon; he'll be 6 next Birthday.

8th Nov 2011, 12:36
Maplin won't sell you one of the lovely AVO meters though. I hope Mr Rivets has taught has boy to treat it with respect.

8th Nov 2011, 12:38
OK thread drift (a bit) but I have a cyristal radio that my Dad built when he was I am guessing it is now about 70 or 80 years old...he used to tell me he could listen to planes landing at Sydney Airport with it...I got it out of his "shed" when he died a few years ago..the thing is I dont know how to use it or how it even works, all I can remember is him telling me something about the "Cats Whiskers..or at least thats what I think I can remember...before he died I had last seem the thing probably 30 years earlier, so over to you fellow Pprunners:ok:

8th Nov 2011, 12:56
One of my favourites was making simple electric motors out of household bits and pieces, like wine bottle corks, paper clips, bits of card board and magnets reclaimed from old fridge magnets, door catches or hard drives. The magnets from old hard drives are brilliant!!

8th Nov 2011, 13:34
You will probably need headphones to hear the output from your crystal set.
I'm not certain whether modern headphones will have the correct impedance.

Crystal radio - Wikipedia, the free encyclopedia (

Crystal Sets (

DIY crystal set radio instructions (

8th Nov 2011, 13:38
My dad's crystal set built in the early-,mid-1920s to hear the first broadcasting stations in US.

I progressed from this to regenerative sets and burning out tubes (valves). They were old at the time and would be rare today.

These headphones were 2000-ohm impedance. I suspect that all/most modern ones are low impedance and wouldn't be suitable for a crystal set.

The slider is an adjustable tap on the coil, which is "tuned" in conjunction with the capacitance of the long-wire antenna. In the mid-1950s we lived across the field from a 50 kW AM broadcasting station. This set gave loudspeaker volume with a very high efficiency high-impedance speaker.

I have spares for the active compnent, the crystal mounted in the bottom of the glass tube. The catswisker is on the end of the rod with the knob.

John Marsh
8th Nov 2011, 14:21
A crystal earphone will work fine instead of 'phones. They're quite cheap. Or, build your own headphones: Making High Impedance Headphones - Jose Pino's Projects and Tidbits. (

Caution to all experimenters, young & mature: remove earphone/headphones from ears before connecting or disconnecting them, or powering up (or down) a circuit. A sharp 'crack' in the ear can permanently damage hearing.:ouch:

Junk... I recommend a healthy junk box, pile or shed to any budding electronics experimenter. It encourages experimentation. If you throw the 'junk' out, you're guaranteed to need some of it shortly thereafter!

8th Nov 2011, 14:49
OK got some good ideas thanks. I've got a load of motors and switches hanging about also bought a packet of plastic propellers and fans today so I think they can go away with something good.

I saw a great one where you get a polystyrene food tray, cut a circle out of the base, turn it upside down and then fit a PC cooling fan on the top. Powered by two 9v batteries its an instant hovercraft.

8th Nov 2011, 14:56
Another idea would be to construct a circuit with some sound device (a buzzer?) and variable controls to create a sort of 'Stylophone' . . .

8th Nov 2011, 15:41
Of course you could have them make marshmallow shooters:

How Toons (

8th Nov 2011, 15:54
I was thinking of getting them to make a coke bottle rocket until I watched a few clips on u tube. They look a bit dangerous, given there's no real launch mechanism other than throwing them on the ground at your feet, at which point they become a bit unpredictable.....

8th Nov 2011, 16:01
This will keep them busy.


May lose one in the process though.

8th Nov 2011, 16:50
Not quite as lethal, but just as much fun:


8th Nov 2011, 18:55
I was thinking of getting them to make a coke bottle rocket until I watched a few clips on u tube. They look a bit dangerous

What could possibly be dangerous about this?


8th Nov 2011, 21:34
Reminds me of "Endurance" used to be on Friday nights when I got back from the pub, or was it "Banzai" (senior moment)

8th Nov 2011, 21:36
What about one of these?

great stuff, how much fun could you demonstrating basic circuits?

A bit of old wire, a pair of wire strippers, a bulb. home made switch (paper clip and drawing pins), power source (mains tends to over-excite things), a buzzer.

Thnk of the fun you could have with building a basic torch, a "trip wire" (clothes peg, buzzer, 2 drawing pins, battery), and one of those "passing a loop round a bent piece of coathanger."

Start with making and breaking a circuit, gate theories and all that will just follow. :)

Solid Rust Twotter
8th Nov 2011, 21:46
Burglar alarm using a basic relay.

8th Nov 2011, 21:51
Yep, great fun. Showed him the basic circuit tonight, and how the motor made the prop turn. When we put the switch in his face lit up, and he ran off to show mum.

Doing a door alarm circuits is great for kids given their siblings are always busting into their rooms and messing up their stuff. Easy to do with a bit of paper between the arms of a spring clip or peg.

Loose rivets
8th Nov 2011, 23:37
Maplin won't sell you one of the lovely AVO meters though. I hope Mr Rivets has taught has boy to treat it with respect.

Yep, this one cost me 14 quid, and the older one I have here in the UK cost much the same years before.

They have stopped production because they cost nearly a grand now. My new in the box one when I was a telly man was offered to me for 18 quid when I left my job. Didn't take it.:{

Oh, my Goodness!!!!!!!!!!!!!!!!

The meters on this tube tester are the things that give out. I had 72 of them and understood the price of these machines was c 1500 quid. Just look at this. Funny thing is, I'd had the movements for over 25 years before I knew what there were from. New in the packets, but nothing like the above AVO 8 in quality. That moving coil movement was supreme.

AVO VCM 163 Tube Tester / AVO VCM 163 Valve Tester Mint Condition !!! | eBay (

9th Nov 2011, 04:41

9th Nov 2011, 09:42
Might want to start with showing them how to take things apart, thereby beginning the long trek involved in learning how to use tools (properly), and a first installment on the manly pursuit of collecting precious bits of seemingly useless stuff -- eventualy leading to the demonstrably increasing need for a shed of one's own.

The ubiquitous manna of today is surplus electronic and electromechanical goods - much of it still operational, that people have cast aside in favour of the latest newer & cute-er model. Such discards are inevitably free or nearly so, and should be easy enough to find. Old VCRs or tape players might be a good way to begin, seeing as how they're simple enough.

For the early rounds it were best to shy away from TV's and Copiers and bug-zappers, or anything that ties very directly to the mains power --- to buy you some time to work up your talk on High-voltages and electrical safety in general, plus VERY high voltages in particular...

Computers are a bit complicated - on the electrical side - for the very young. A kid-oriented project for some simple programming might begin to light their lights on the inherent complexity of such things. But the enclosures and power supplies and fans and such in discard pc's might be good prizes that could be easily scavenged -- to become a part of the youngsters' armamentarium for future projects.

Some adult supervision is necessary for teaching about the sharp aspects of tools and electricity, but short and pointy explanations can keep it brief. Charging up a SMALL VALUE capacitor** to a hundred volts or so & then touching the leads with two adjacent fingers, one on each lead, is a rough but moderately safe way for 'em to get the tricky point across, one reckons. If they persist in repeating the experiment a great many times, that might be a sign that a high degree of supervision will be necessary. Similar with tools, eh?

Don't leave the girls out, if there be some in your crew. It's a new age, the Mrs. says.

The best single investment might be a fairly inexpensive Volts-Amps-Ohms meter. Not very expensive these days, and moderately durable -- especially if 'tis the kind with a digital display (that knows how to protect itself some). Having the use of one of these will let the sprouts measure and explore some aspects of the parts and things they rip out of other stuff, and so eventually will help lead them through curiosity toward a vision of the immense possibilities for learning that are waiting patiently within their easy reach.

**0.01 to 0.05 mf, maybe

9th Nov 2011, 10:38
I once hired a beginner engineer who turned out to be useless. We built one-of-kind lab apparatus and even beginners had to be somewhat self-reliant.

This fellow had good grades, but didn't dare "do anything". He was afraid of breaking things. I learned that his father had been "Insurance Commissioner" of a major US state.

I am convinced that he was never allowed to take things apart or break anything in his youth. Having some grasp of how mechanical or low-power electrical things work is valuable no matter what sort of work one eventually does.

My experience was that the best beginner engineers (incl. young women) were children of engineers, of high-level technicians or of farmers. They already understood the concepts of analyzing a problem and then designing and putting something together that worked.

A retired friend (BS in Physics, MS in Math, PhD in computer science) has been taking "art" courses at the local junior college.His recent projects have involved recreational welding. He told of a fellow student - retired partner in a significant law firm -whose projects tended to fall over or otherwise break. The lawyer had no grasp of center-of-gravity or the forces in structures.

Seven sounds pretty young to expect much technical understanding. Maybe I had a Mechano (or equiv) set at 8 or so. I started building regenerative one-tube radios at age about 12 and built a superhet at about age 14/15. I now conclude its IF oscillated, but ... These were all done from scratch, I never had any kits. My dad's ancient junk box helped. His expertise was mechanical engineering / patent law and he didn't have much RF knowledge.

Now-days, with "wall wart" power supplies and solid-state electronics, electrical safety is much easier.

spInY nORmAn
9th Nov 2011, 16:15
I got one of these in the late 60's when I was about 13 years old - sparked a lifetime interest in electronics. I loved being able to hook up a bunch of parts the likes of which I was totally unfamiliar with up until I got this kit, and actually being able to make a radio/"burglar alarm"/moisture detector etc. This was the Philips "Electronic Engineer" kit - EE-20 complete with fiddly spring connectors that required bending the wires on the components until they inevitably broke off. The kits I see around today are much more modular - don't seem to give today's youth too much credit to be able to actually connect actual components thereby gaining at least a rudimentary understanding of what they do and how they work. I actually read the manual that came with this and actually learned something! Nowadays, it's all "black box" technology. Oh well, I guess nostalgia ain't what it used to be!

Here's a piccie of the Philips kit:

Been Accounting
9th Nov 2011, 17:32
Lots of ideas on Instructables - Make, How To, and DIY (

9th Nov 2011, 21:12
What more does a boy want than Spiny Norman's kit?

Take the point about kids just not getting it today- it's all too disposable.

Went to the 'eld fella's today, he was showing me some old "Meccano" magazines-full of adverts for air guns, remote control planes and Mammod steam engines. Almost makes me wish I was born in the 40's.

Bought this at a car boot sale when I was down country this spring.It cost 3 quid, and I was able to make a decent antenna with a bit of hoover cable, four cable ties, and a chock block (must admit, had to get gingerette to "google" instructions on her Blackberry:}-for anyone who's interested, the crucial length is 105 inches) Wired up to the Vauxhall with a few crocodile clips, and bob's ya'uncle, aunt's ya fanny.....

Kids were absolutely fascinated, and still enjoy the thrill of talking to a swearing scouser with a "burner" even now.

Windy Militant
9th Nov 2011, 21:27
I was thinking of getting them to make a coke bottle rocket until I watched a few clips on u tube. They look a bit dangerous
Not electronic. but how about a "Stomp Rocket" Dead simple, plastic pop bottle length of hose and a paper rocket made from an A4 sheet. Plenty of instructions as to making them ont interweb there's even one on the NASA web site.

Or how about a simple electro magnet? Years ago I had a book from the school library which had a number of projects using solenoids. I built a buzzer from an old tin can, a length of wire a battery and a six inch nail.
How about a bomber game, like the one at Hendon?

9th Nov 2011, 21:46
Nice to see an old AVO 7(looks like a 7). Was standard issue in the Army though must admit the meter movement took quite a hammering.
Basic training was after DC and AC generation and motors, then valve circuits and these new fangled things called transistors.Problem was no one could make up their minds whether things flowed from -ve to +ve or the other way round, "hole flow" got me confused and was quite happy with "electron flow" at the end of the course you built a superheterodyne, you cetainly learnt that 400v DC was not a voltage to be touched and sat on stools the instructor had a "shock chart" on the blackboard to register who got "belted" the most times.
"Winner" had at the end of the course to buy a pint for the rest of the course. I learnt very quickly!!

10th Nov 2011, 04:45
Why not get him to build a warp engine? Would keep him
busy the whole week.

He would need -

One (1) Bussard Collector and intake housing
One (1) Matter Collection Bottle
Four (4) x 1kg Dilithium crystals (refined)
Twenty two (22) kg antimatter (anti Helium)
Twenty two (22) kg matter (Helium)
One (1) Helium container
Two (2) space matrix restoration coils
One (1) Dilithium crystal chamber
One (1) antimatter magnetic bottle
One (1) matter-antimatter mixing chamber
One (1) warp engine nacelle
One (1) spanner
One (1) glove

1. Fit the matter-antimatter mixing chamber halfway down
the warp engine nacelle, then attach both antimatter and
Helium matter bottles to either side of the chamber.

2. Insert the Dilithium crystal chamber in its alloted port
on the mixing chamber, then place the crystals inside it.

3. Bolt each restoration coil to the fore and aft positions of
the warp nacelle. Attach Bussard collector and housing to
the most forward section of nacelle, and attach its hose to
the matter collection bottle.

4. Turn on antimatter bottle and adjust using the spanner.
Use the glove if magnetic flux is above the users tolerable
Tesla limit.

4. Fill the antimatter bottle with anti-Helium (don't spill
any!) and the Helium container with Helium respectively.

5. Check the mixing chamber is set to 1:1 ratio to ensure
smooth operation.

6. Check crystals are tuned to the harmonic of the matter-
antimatter core frequency

7. Ensure that each space restoration coil is correctly set
to either FWD or AFT - otherwise the miscompression and
misexpansion of Space will result.

Engine now ready to go! :)

Solid Rust Twotter
10th Nov 2011, 07:02
Requires a thronomister with polarity reversed flange cranulator for precise linear vector control too, Mr Slash.

spInY nORmAn
10th Nov 2011, 07:09
Don't forget the turbo-encabulator!

10th Nov 2011, 09:56
I started with a present from an uncle - a shoebox with wire, batteries, lampholders, terminal block, a buzzer and an old morse key. That kept me amused and then I went on to the aforementioned Philips Electronics Engineer kit. I ended up building infrared astronomical cameras and spectrographs, designing embedded parallel computers and managing large telescope construction, although the boxes of bits were rather larger, as was the toolkit. Decades of fun.

I hope the lad enjoys his project.

10th Nov 2011, 10:22
One (1) Bussard Collector and intake housing
One (1) Matter Collection Bottle
Four (4) x 1kg Dilithium crystals (refined)
Twenty two (22) kg antimatter (anti Helium)
Twenty two (22) kg matter (Helium)
One (1) Helium container
Two (2) space matrix restoration coils
One (1) Dilithium crystal chamber
One (1) antimatter magnetic bottle
One (1) matter-antimatter mixing chamber
One (1) warp engine nacelle
One (1) spanner
One (1) glove

no duct tape ?

Solid Rust Twotter
10th Nov 2011, 11:33
As an aside, can one still get good quality water propelled rockets? Had a great one as a kid but all I see on Amazon now is some low budget Chinese made dodgy number which, judging by the fan mail attached to the page, doesn't work. I remember seeing one in a catalogue back then that came with a pop open nose cone and a parachute. How one lusted for that.

11th Nov 2011, 01:58
Here's a few sites that I use for various projects around the home, model railway, scaring the cats, etc. :ooh:

Good site for beginners: Site Map for the Electronics Club (
Lots of good projects here: RED Free Circuit Designs - Audio (
And also here: Electronic Circuits - Free Electronic Circuits (
Mainly model railway-orientated, but a very interesting selection of projects: Model Railroad and Misc. Electronics (

If I find any more, I'll add them to the list.



Oh, Slasher - You have (5) and (6) transposed. :}

11th Nov 2011, 02:57
A very simple demonstration of "lift" aka the Bernoulli effect, is to hold a 8.5 x 11 inch sheet of paper crosswise just under your mouth and blow over the top. It will rise.

This may be too boring to last long as entertainment.

Another fun experiment, if you want to teach them about density, is to take a bucket (or something wider) full of water and see what happens if you put in 12 ounce cans of diet soda and soda with sugar and see which floats or sinks.

Hint, or a giveaway, the sugar makes it denser than water, so it sinks. The artificial sweeteners are present in such low concentration that their presence doesn't matter, and the air in the soda can makes it float.

They can bob for apples, but perhaps that's too much for age seven.
Apple bobbing - Wikipedia, the free encyclopedia (

The ACS is into science education, so check out:
Science for Kids (

Electricity Article (

11th Nov 2011, 04:23
Growing up in the '60's I had an assorted and very second-hand collection of dog-eared Phantom/Superman style comics. On the very back page of many of them was a black & white photo and an advertisement for a real fair dinkum submarine you could sit in that roolly floats. Of course it came from America and as a kid I often wondered if I wrote away to them would they actually send me one. Today, I now wonder if such a thing actually existed. Do any US readers remember them?

Solid Rust Twotter
11th Nov 2011, 05:38
Lusted for one of those mini subs too, Mr Osmosis. HSE would probably ban them today.

12th Nov 2011, 19:07
Well, it seemed to go Ok. Since the weather was OK today we first did some orienteering in the field behind the house. following compass bearings to find chocolate I had secreted earlier.

Then I got them to build a very basic circuit, battery to switch to motor and back again, we stuck some plastic propellers on the end of the motors which were most satisfactory, they all seemed to enjoy it.

Pizza and ice cream rounded it off. Thanks all for your suggestions, I found myself going back to things I haven't done since I was a kid, and was reminded how much fun just mucking about with stuff (and being outside) is.

As an aside thinking about this over the last couple of weeks meant I rewired the number plate lights on my motor so that they worked and would pass the MOT (it did) rather than paying the garage to do it (austerity measures and all).

Cheers, GB

12th Nov 2011, 21:17
Spiny, I was given one of those kits at about the same time as yourself. Those connectors were quite fiddly. Never managed the warp drive option.


12th Nov 2011, 22:27
no duct tape ?

Any warp engine doesn't require a thronomister with polarity
reversed flange cranulator for precise linear vector control, so
no duct tape is therefore necessary.

You have (5) and (6) transposed.

Nope. My 3yo bloke's UFP Memory Alpha Archive Warp Engine
Construction Manual says clearly that crystal tuning is to be
done AFTER the mixing chamber is set 1:1. You're forgetting
a warp theory basic which says positronic flow of the inducer
coils to both flux ports cannot continue after achieving Warp
One (positrons are matter) thus trapping you just below the
speed of light and taking all bloody day to get anywhere. At
0.2c the Bussard Collector intakes are automatically opened.

12th Nov 2011, 22:35
I remember seeing one in a catalogue back then that came with a pop open nose cone and a parachute. How one lusted for that. We had one of those. Unfortunately one of the fins broke off on a trial launch and despite gluing it back on, it could never hold the pressure to get a decent launch. The small white rocket with the translucent red nosecone went well until the pump seal went.

Our big rocket was the one in the left of this picture. I seem to recall the red Mercury type capsule and the white one on the second from left rocket.

My brother and I were incredibly fortunate to have aunts and uncles in both Canada and the USA, and the list of toys that flew eastwards across the Atlantic on birthdays and Christmases was endless. Even so we drooled over the stuff in the Sears catalogue (must have been about 1969 vintage).

Names I remember include:

Tinka Toys - orange plastic assembly toy with wooden wheels and axles
Hot Wheels (long before it arrived here) including the rechargable Sizzlers cars
GI Joe - mine was a talking astronaut - there was no military stuff as the Vietnam War was on
Mattel's Man in Space - An astronaut about 7" high which had loads of pneumatic accessories usually actuated by a small bellows
Strange Change - a cooker the 'elf 'n safety people would have a fit at. It turned small plastic squares into dinosaurs and a built in vice turned them back again. It burned small fingers equally well.
Cox PT-19 - despite being rubber banded together it seemed to break regularly, when trying the wingover shown on the box. Taught us to fly control line though
Smash Up Derby - A couple of stock cars with flywheels spun up with a plastic toothed belt. When the cars hit the panels flew off.
A huge tinplate B-47 with a nosecone that was lit with sparks. My brother had that. I'm sure it was around before I was.

I remember those ads in the American comics 'build your own pulse jet to drive a scooter'. Did any of those things really exist?

13th Nov 2011, 19:46
Toys for boys and their dads

Quasar Electronic Kit Module Project UK: Industrial Educational Hobby (

Windy Militant
14th Nov 2011, 08:21
I remember those ads in the American comics 'build your own pulse jet to drive a scooter'. Did any of those things really exist?

I don't know if it was for driving a scooter but I once welded up a stainless steel exhaust duct for one of these for one of our apprentices.
I never saw it run as the lad was seconded to our section from a certain secret atomic research establishment and returned to work with the transort section there before the device was completed.
Apprently when he did get the thing running, by attaching it to a bench and using a compressed airline to start it, it dragged the bench with him and three mates trying to hold it back across the workshop.
It also got the AEA plods in a bit of a tizzy as the noise it made was reported as an explosion on site! :O

14th Nov 2011, 10:59
Slasher, you appear to have neglected some other 'ingredients'.

"Take the juice from one bottle of that Ol' Janx Spirit.
Pour into it one measure of water from the seas of Santraginus V
Allow three cubes of Arcturan Mega-gin to melt into the mixture
(it must be properly iced or the benzene is lost). Allow four litres of Fallian marsh gas to bubble through it (in memory of all those happy Hikers who have died of pleasure in the Marshes of Fallia).

Over the back of a silver spoon float a measure of Qualactin

Hypermint extract, redolent of all the heady odours of the dark Qualactin Zones.

Drop in the tooth of an Algolian Suntiger. Watch it dissolve, spreading the fires of the Algolian suns deep into the heart of the drink.

Sprinkle Zamphour.

Add an olive.

Drink...but very carefully."