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Playdough For Fun and Profit

timothy posted more than 2 years ago | from the not-the-trademarked-version dept.

Hardware Hacking 70

morgan_greywolf writes with this snippet from Wired:"You're never too young (or too old) to start learning the joys of electronics. You don't need to know how to solder, or even how to plug circuit components into a breadboard. As long as you're past the 'I'm going to stick this up my nose' phase, this homemade playdough circuit project is a great way to introduce kiddos and adults alike to basic circuits and electricity."

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70 comments

yeah (2, Interesting)

buanzo (542591) | more than 2 years ago | (#36707828)

useful, cool, geeky and pro-learning and DIY. great.

Re:yeah (3)

davester666 (731373) | more than 2 years ago | (#36708322)

We MUST put a halt to this immediately. We can't have children messing about with this kind of thing.

Hell, terrorists might even try to build the electronics for a bomb using this in the middle of a flight, because the TSA still lets you have playdough. Combining this with the C4 they have stuffed inside body cavities, it's like manna from heaven.

Re:yeah (3, Interesting)

mcgrew (92797) | more than 2 years ago | (#36710398)

I'm surprised they let you have paydough on planes.

What would be better than powering the circuit with batteries would be to make the batteries, too. You can make a battery from a lemon, a galvanized roofing nail, and a piece of thick copper wire. Not sure if it would power an LED (Although I'm pretty sure it would) but I suppose you could have a six (or more) lemon battery. A single lemon will power an LCD calculator, I did that with my kids when they were little. You can get around a volt from a lemon, not sure how many milliamps. And I don't remember if the copper side or the zinc side was positive; the kids are grown now and it was a long time ago.

The LED is good for demonstrating the workings of a diode, since it is a diode and lights up. A red/green diode is great for that, one of the ones that light red with one polarity, green with the opposite polarity, and yellow with AC.

Seems you could make a playdough capacitor, too. You could conceivably make playdough resistors by mixing the conductive and nonconductive doughs. I wish I'd known the conductive properties of playdough when my kids were little. Maybe if one of them makes me a grandpa...

Re:yeah (1)

Hadlock (143607) | more than 2 years ago | (#36710770)

I'm imagining a 3 year old filling the holes on an electric socket with the blue (conductive) playdoh. ZAP.

Re:yeah (1)

Abstrackt (609015) | more than 2 years ago | (#36714484)

That, and learning how hard playdough is to remove from carpet, is why you always make your kids play with it at the table.

Re:yeah (1)

hairyfeet (841228) | more than 2 years ago | (#36709480)

Uhhhh...while it is a cool little thing, although how many things you'll be able to make with a playdough circuit is debatable....don't they still make those little cheap "X in One" kids hobby kits anymore?

When I was a kid all the little geeky kids (like me) had these little "X in One" like 24 in One, 40 in One, etc little electronic kits that let you make really cool stuff, like a radio, a little LED counter, I think the bigger ones even let you make a walkie talkie. And just about any kid 7 and up could use those which if they are below 7 I doubt they are gonna understand much with the playdough circuit either.

So why would you want to do this rather than sit with your kid and one of those X in One kits? Are those just not cool anymore?

Re:yeah (1)

artor3 (1344997) | more than 2 years ago | (#36709644)

I think the idea here is to use it with very young kids, maybe down to three years old. Save the breadboarding until they're old enough to use wirecutters without removing an earlobe. It's like training wheels or tee ball. Obviously inferior to the real thing, but an accessible start. Little kids are used to playing with playdough. If you can sneak in some learning, all the better.

Re:yeah (1)

Hognoxious (631665) | more than 2 years ago | (#36711946)

Who said anything about breadboarding? If the things GP's referring to are like the one I had, the components are on little mounts that bolt into place on a precut predrilled PCB.

oh yeah! (1)

blackbeak (1227080) | more than 2 years ago | (#36707890)

My son (7) has been playing around all day with parts from a gutted (hacked) Hess truck. Play dough electrical connectors are just perfect for him now! Thanks, OP.

ban playdoh (0)

Anonymous Coward | more than 2 years ago | (#36707918)

Obviously Playdoh is dangerous to our children. I heard about Playdoh electrocutions, and this is now proof.

looks like a bomb better send in the FBI (2, Insightful)

Joe_Dragon (2206452) | more than 2 years ago | (#36707948)

Now this is some that if left in the open will look alot more bomb / C4 like then the Aqua Teen Hunger Force ad's.

Re:looks like a bomb better send in the FBI (-1)

Anonymous Coward | more than 2 years ago | (#36708076)

Fuck you cunt. We're sick of your shit.

Re:looks like a booger better send in the Tissue (3, Funny)

Anonymous Coward | more than 2 years ago | (#36708412)

As long as you're past the 'I'm going to stick this up my nose' phase

It's narrow minded people like you that hold back scientific progress, the smelloscope is a fantastic invention.

Re:looks like a booger better send in the Tissue (0)

Anonymous Coward | more than 2 years ago | (#36713578)

If I stick the conductive playdough in each nostril and use it as a circuit, would my nose be conductive or insulating? I guess it would depend on how much conductivity the playdough has or how much power I'm using. If I use AC, would my nose's capacitance be a factor? I'll let you all know.

Re:looks like a bomb better send in the FBI (1)

mcgrew (92797) | more than 2 years ago | (#36710416)

Mix in a little saltpeter and you do have an incendiary device. Saltpeter mixed with sugar will burn through a concrete block once lit.

Power it with enough lemons and it won't even look like a bomb, although a saltpeter bomb has to be under pressure (pipe bomb).

Re:looks like a bomb better send in the FBI (0)

Anonymous Coward | more than 2 years ago | (#36711644)

TSA Agent: "He just has a lot of colored playdough and a potato. Let him on the plane."

I should've known this when I was young (1)

Anonymous Coward | more than 2 years ago | (#36707980)

I used to rip apart all toys and wire up motors, blinken lights and stuff using clay. (I used clay to keep the connections in place)

Potato battery (0)

Anonymous Coward | more than 2 years ago | (#36708052)

Beware of birds !

See also AnnMarie Thomas' TED talk (2)

rgm3 (530335) | more than 2 years ago | (#36708112)

If you like this, you may enjoy the TED talk video about it: http://www.ted.com/talks/annmarie_thomas_squishy_circuits.html [ted.com]

Re:See also AnnMarie Thomas' TED talk (1)

iamhassi (659463) | more than 2 years ago | (#36708878)

Yeah but AnnMarie Thomas [hulu.com] isn't nearly as attractive as the Christina Bonnington [facebook.com]

not that I choose videos based on the attractiveness of the woman in the video...

Christina has 68 likes, wonder how many she'll have after /. is done with her?

Semiconductor playdough (1)

Anonymous Coward | more than 2 years ago | (#36708190)

Needs P and N type dough!

Alligator Clips (1)

chazchaz101 (871891) | more than 2 years ago | (#36708212)

They're cheap, don't make a mess, don't dry out, and probably conduct better too.

Re:Alligator Clips (2, Funny)

Anonymous Coward | more than 2 years ago | (#36708280)

yeah, but because of the decline in alligator population, the clips are becoming rare. plus PETA kept picketing Radio Shacks

Re:Alligator Clips (2)

mcgrew (92797) | more than 2 years ago | (#36710428)

Also they make great roach clips. Playing with kids and simple electronics is even more fun when you're stoned!

Alligator clips have a multitude of uses, most of which have nothing to do with electronics.

4 year old? (1)

keith_nt4 (612247) | more than 2 years ago | (#36708222)

My niece is turning four soon, anybody think that is too young for this? She does love play dough.

Re:4 year old? (4, Interesting)

carlzum (832868) | more than 2 years ago | (#36708298)

Not at all. I started doing kitchen experiments with my daughter when she was 3. Once she gets how one conducts and the other doesn't, she'll be able to try different combinations and see how the current moves, degrades, etc. She may not learn the technology, but a four year old's ability to learn through experience is incredible. Don't forget, she learned English in less than two years using observation alone.

Re:4 year old? (1)

carlzum (832868) | more than 2 years ago | (#36708364)

Not at all. I started doing kitchen experiments with my daughter when she was 3. Once she gets how one conducts and the other doesn't, she'll be able to try different combinations and see how the current moves, degrades, etc. She may not learn the technology, but a four year old's ability to learn through experience is incredible. Don't forget, she learned English in less than two years using observation alone.

oops... I meant to say, she may not learn the terminology

Re:4 year old? (1)

drolli (522659) | more than 2 years ago | (#36709656)

I think my father made me some LEGO bricks with LEDs and lamps when i was four and i remember that i was very fascinated by the fact that some devices which have a polarity, and some don't. I for sure expressed that in another way, but testing how to attach the red/black wires to batteries to make the LEDs shine kept me busy and quiet for some time. And my development was completely average.

My theory is: give children many kinds of toys. You will figure out if its to early if they don't play with it.

Re:4 year old? (1)

mcgrew (92797) | more than 2 years ago | (#36710434)

It depends on the kid. My oldest would have been five before she would grasp it (she's learning disabled), my youngest could have handled it at two (she's gifted).

Re:4 year old? (1)

Abstrackt (609015) | more than 2 years ago | (#36714508)

Kids are all so different that it's hard for anyone but you (and her parents of course!) to answer that question. I say just give it a shot under extra-close supervision and see what happens, you can always put it away if you think she's not ready.

woot (-1, Flamebait)

Osgeld (1900440) | more than 2 years ago | (#36708262)

way to post a recycle of a recycle of a recycled 6 month old article

http://courseweb.stthomas.edu/apthomas/SquishyCircuits/ [stthomas.edu]

would it kill you fucks to use google?

Re:woot (1)

Anonymous Coward | more than 2 years ago | (#36708316)

would it kill you fucks to use google?

I'll make you a deal: I'll start using Google to filter submissions if you start using even a token amount of civility.

Re:woot (1)

mcgrew (92797) | more than 2 years ago | (#36710446)

I found it interesting. Just because you've seen a similar article doen't mean everybody has. I see you were modded flamebait, if I were moderating today your comment would be at a -1.

Bad comment! Bad bad bad! *swats comment on nose with rolled up newspaper*

Re:woot (1)

Osgeld (1900440) | more than 2 years ago | (#36712466)

it already is -1 dink, and I thought this was a news site, not the same old shit everyone else it reposting site

Re:woot (1)

mcgrew (92797) | more than 2 years ago | (#36719034)

If you haven't seen it before it's news. And, are book reviews news? Nope. Yes, this is news for nerds, but not all stuff that matters is news. If you don't like a topic, ignore it, there are lots more where they came from.

If you'd worded you comment like below you would have been modded up:

This isn't new, I saw it six months ago

http://courseweb.stthomas.edu/apthomas/SquishyCircuits/ [stthomas.edu]

+3 informative.

It makes no sense to word a comment is such a way that it's sure to be at a -1. If nobody is going to see it, why comment at all?

Now get off my lawn, kid. Sheesh.

It is almost like.... (2)

Tehrasha (624164) | more than 2 years ago | (#36708276)

..breadboarding, with bread dough. When I first saw the pics, I thought they had found a way to simulate semi-conductor doping with the different colored dough.

Re:It is almost like.... (2)

RobertLTux (260313) | more than 2 years ago | (#36708324)

actually given the way a diode is made you MIGHT be able to actually do a diode by making dough with a varied mix of salt/tartar
along the length of your dough

Re:It is almost like.... (1)

artor3 (1344997) | more than 2 years ago | (#36709572)

I don't see how. There are only three ways I know of to make a diode. You can use semiconductors, quantum tunneling, or the old vacuum tube method. I can't see how varying the resistivity of the dough could replicate any of those.

What you could do is make a moderately resistive dough, and create a potentiometer. Battery+ -> wire -> dough -> LED -> Battery-. Roll the dough into a thin strand, and the light gets dim. Clump it into a big ball, and the light gets bright. Bonus points if you explain pulse width modulation to your kid and get them to control the brightness the right way.

Re:It is almost like.... (1)

Tehrasha (624164) | more than 2 years ago | (#36714470)

There are only three ways I know of to make a diode. You can use semiconductors, quantum tunneling, or the old vacuum tube method.

Which of these three do Selenium rectifiers [wikipedia.org] fall under?

Re:It is almost like.... (1)

artor3 (1344997) | more than 2 years ago | (#36715094)

Under the "ways I do not know of" heading. However, wikipedia says they're an early type of semiconductor diode, so I'll go with that.

Re:It is almost like.... (1)

RobertLTux (260313) | more than 2 years ago | (#36715712)

lemme correct things before my semi conductor teacher whacks me upside the head

you would actually make a nonconductive dough and then mix in gallium or antimony depending on which type you need (i think those are the least toxic of the possible options) so a "proper" diode would have gallium on one end and antimony on the other end

you could maybe get a sort of bipolar junction transistor by making a blob with Npn sections but this would just about be stone knifes and bearskins level of operation.

p-type & n-type playdough ? (0)

Anonymous Coward | more than 2 years ago | (#36708420)

Ah but is it possible to make semi-conductor playdough?
That would really be useful in learning basic semiconductor theory.

Yet inconceivable... (1, Interesting)

retroworks (652802) | more than 2 years ago | (#36708442)

That an Egyptian can fix a bad joint on a laptop. Americans are going to be banned from selling laptops with loose power adapters (the number one cause of failure of several Dell and Lenovo and other models) under legislation introduced by Green-Thompson "ewaste". Only "tested working" electronics can be resold. Vermont now bans sale between Vermonters without a hazardous waste permit. We know the issue is the adapter plug (people carry the laptop around with the plug inserted, and it breaks the solder). But it is about to be made illegal to sell laptops etc. for repair, even if the Egyptian/Indonesian/Peruvian knows schematic diagrams AND is also more than 4 years old(!). Maybe if we make laptops out of play-dough, they will be considered less "hazardous", though currently even play-dough laptops are covered by Vermont E-waste law. Imagine this applied to cars - if it doesn't pass inspection, it's haz waste, moon suit tow trucks.

Kirkchoff's law fail (4, Informative)

Zinho (17895) | more than 2 years ago | (#36708970)

It makes me sad to read the following snippet from the article:

Chain multiple LEDs through the conductive dough, and you’ll notice the ones at the end are far dimmer than the first few. That’s because less current is making its way down the series; the current only has one path, and that’s through each LED.

Now a bunch of kids are going to go through life thinking that current gets used up as it goes through the circuit. The same current will be flowing through every component of the circuit; it's only got one path, after all.

Don't get me wrong, I love this article and I'm probably going to try this with my kids, too. It's just that I'm going to teach them Kirchoff's laws [wikipedia.org] while I'm at it.

Re:Kirkchoff's law fail (1)

artor3 (1344997) | more than 2 years ago | (#36709624)

The article is a wiki, so you can fix it. I'd do it myself, but I haven't actually made the playdough (yet!) and I want to see for myself if the LEDs further along in the circuit don't shine as bright. My gut says that the current author didn't actually try it and was just writing what he expected to happen, since I can't think of any reason for it to be true, but it wouldn't be the first time a circuit has surprised me.

Re:Kirkchoff's law fail (0)

Anonymous Coward | more than 2 years ago | (#36710246)

No, they tried it but the text in the wiki is not very clear.
As they explained in the video clips on the page the "conductive" dough is actually resistive dough. (80ohm/cm when rolled to a cylinder with a diameter of 1cm.)
Because of the way the text was written you assumed that the "chain" was a chain of multiple LED connected in series. In the video clips on the homepage the chain they speak of is a parallell circuit and since the LED furthest away has most dough in it's path it will also have a higher series resistance.

Re:Kirkchoff's law fail (0)

mcgrew (92797) | more than 2 years ago | (#36710500)

No, LEDs are only full brightness or off. To make an LED dim you pulse the current through it. It isn't actually dimmer, it just looks dimmer because it's turning on and off faster than you can see.

Re:Kirkchoff's law fail (3, Insightful)

Clueless Moron (548336) | more than 2 years ago | (#36711124)

No, LEDs are only full brightness or off. To make an LED dim you pulse the current through it. It isn't actually dimmer, it just looks dimmer because it's turning on and off faster than you can see.

Nonsense. You can make an LED anything from barely lit to full tilt by nothing more than controlling the current via the loading resistor. Try it yourself.

Re:Kirkchoff's law fail (0)

Anonymous Coward | more than 2 years ago | (#36717558)

And all you would need to try it are an LED, a few resistors with values between 100 and 3000 ohms or so, two AA batteries, and that conductive dough.

Re:Kirkchoff's law fail (1)

Hognoxious (631665) | more than 2 years ago | (#36745628)

When I unplug the power supply for my netbook, the LED decays quickly, but not instantaneously.

Which is more likely?

a) A capacitor that's there for some other reason (smoothing?) is discharging. I know they are they, I've been zapped by one.

b) The manufacturer went to the time, effort and expense to add pulsing circuitry that 99.99% of people won't even notice the effect of.

Re:Kirkchoff's law fail (1)

mcgrew (92797) | more than 2 years ago | (#36747416)

I'd say a). Big caps can hold a charge for a while. Most people don't realize you can be fatally electrocuted by a CRT TV that isn't even plugged it if you put your fingers in the wrong place.

Re:Kirkchoff's law fail (1)

BobJacobsen (536197) | more than 2 years ago | (#36711818)

It's part of a Wiki, but you can't edit it (though it says you can). If you try, you get "The action you have requested is limited to users in one of the groups trusted, Sysops." You even get that on the discussion page for that article.

Re:Kirkchoff's law fail (1)

ipwndk (1898300) | more than 2 years ago | (#36710160)

But the dough probably have some resistance?

Re:Kirkchoff's law fail (1)

BobJacobsen (536197) | more than 2 years ago | (#36711846)

Yes, it does. And that will determine how bright _all_ the LEDs are. But the LEDs are all getting the same current because they're in series: All of the current goes through one, then the next, then the next. Each gets no more or less current than the others. So, if they're all the same type of LED, they'll all be the same brightness. The Wired article even got this partly right: "Chain multiple LEDs through the conductive dough, and you’ll notice the ones at the end are far dimmer than the first few. That’s because less current is making its way down the series; the current only has one path, and that’s through each LED." I think they were trying to say "as you add more and more LEDs, they get dimmer", not that the LEDs in any particular setup are different from each other.

Re:Kirkchoff's law fail (1)

O('_')O_Bush (1162487) | more than 2 years ago | (#36712196)

Well, current could be "used up" as it goes through the circuit... Given that the playdough has a large surface area to the table (making the table an imperfect ground), it would probably be making a ladder circuit between the diodes, causing partial shorts which would explain the fading brightness of the LED's down the chain.

Re:Kirkchoff's law fail (0)

Anonymous Coward | more than 2 years ago | (#36717598)

No, diodes (including LEDs) have a forward voltage drop of about 0.7 volts from the anode to the cathode. So if you place them in series, each one drops the voltage a little, and lower voltage means dimmer LEDs.

Re:Kirkchoff's law fail (1)

Zinho (17895) | more than 2 years ago | (#36721218)

You are correct that the voltage (as referenced from the negative battery terminal) drops by 0.7V across each LED, but that doesn't make the next one in the series dimmer. Kirchoff comes to the rescue again: his voltage law states that the sum of voltage around a closed circuit is zero.

For our case, that means that the sum of forward voltage across your LEDs plus the voltage drop across your current-limiting resistor will equal the battery voltage. Each LED will have the same voltage drop across it (put a multimeter on the LED's leads and each LED will register 0.7V, +/- manufacturing tolerances). If you have 4 LEDs and a 3V battery pack then the four LEDs will take you a total of 2.8V down from your initial 3V potential, and your circuit current will be determined by Ohm's law and the value of your current-limiting resistor (I=0.2V/R, the current will increase until the potential drop across your resistor is 0.2V). Kirchoff's current law says that the sum of current out of the battery must equal the sum coming back in, and since there is only one circuit path each LED will have the same current across it.

Each LED will experience the same electrical conditions as all of the others: each has a voltage drop of 0.7V per LED, and each sees the same current. Since LED brightness is determined by the current across it, and each LED has the same current because they're in series, then they should all have the same brightness (again, manufacturing tolerances may apply here). Each LED should also have the same brightness as it would if it were alone in a circuit with a 0.9V power supply and the same size resistor. The fact that there are four of them stepping the voltage down from 3V as opposed to just one stepping down from 0.9V doesn't make a difference; at the same current they'll have the same brightness.

Cool idea, but seems rather limited (1)

Just Brew It! (636086) | more than 2 years ago | (#36709042)

Can't make a zero-resistance connection; this is going to constrain things quite a bit. But as a stepping stone to get kids interested, it's great!

My introduction to electronics back in the day was a Radio Shack "65-In-One" electronics project kit. Bunch of discrete components, meter, speaker, photocell, electromagnetic relay, etc. with spring clips that allowed for easy interconnection. It's sad that this sort of thing is no longer widely available.

Re:Cool idea, but seems rather limited (0)

Anonymous Coward | more than 2 years ago | (#36713148)

Just bought a 50 in one from Fry's. Not exactly hard to find.

Potato (0)

Anonymous Coward | more than 2 years ago | (#36709132)

Instead of making dough, you could use potato pieces. Easier and less messy.

Better than breadboard? (1)

sourcerror (1718066) | more than 2 years ago | (#36709626)

How is it better/easier to use/more educational than a breadboard?

Re:Better than breadboard? (1)

camperdave (969942) | more than 2 years ago | (#36711428)

Because it's a lot easier for a kid to stick a wire into a lump of dough than to stick it into the right hole in a breadboard.

What? No semiconducting PlayDough? (1)

Ramin_HAL9001 (1677134) | more than 2 years ago | (#36809434)

This is USELESS!!!
They don't explain how to make positive/negative doped PlayDough. How the hell do they expect us to create PN-junctions? No amplifiers, no digital logic, this is totally, totally useless.
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