Naked Science Forum
Non Life Sciences => Technology => Topic started by: Onlyinterestednotdevoted on 17/11/2008 23:39:30
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I need an electronic device to create a pulse. I will provide a source of electricity and I need something to make it pulsate in a sequence. For example, 4 lightbulbs that shine in sequential order. But one can not shine until the other has died out. I want to arrange the machine in a circle pattern, with 4 points. Can someone please give me some ideas? Thanks.
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I need an electronic device to create a pulse. I will provide a source of electricity and I need something to make it pulsate in a sequence. For example, 4 lightbulbs that shine in sequential order. But one can not shine until the other has died out. I want to arrange the machine in a circle pattern, with 4 points. Can someone please give me some ideas? Thanks.
I suggest a home made single post generator with a governor to time out the pulse.
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This circuit (http://www.kpsec.freeuk.com/projects/heart.htm) uses 8 (not 4) LED lights which light in sequence to create a heart shaped display, (it could be a circle)...
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The circuit could be modified for only 4 lights by changing the reset link on the 4017 chip (http://www.kpsec.freeuk.com/components/cmos.htm#4017) to reset on the 5th count,
by connecting pins 15 and 10.
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If you're starting with no previous knowledge then you need to buy an experimenter's kit. In the UK, Maplin sell these things. Radio Shack do it in the US, I believe.
You'd get a circuit board, components and construction information. That way you'd have a good chance of actually getting a result.
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I think the cmos chip 4017 (CD 4017) produces outputs in sequence. You might need driver transistors to switch high power LEDSs etc.
You could combine two outputs via diodes to give you 5 instead of ten.
http://www.talkingelectronics.com/ChipDataEbook-1d/html/4017.html
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I thought, from reading the original question that a simple kit would be more likely to produce a working device. First time round this sort of exercise is full of problems.
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The link I gave does offer a kit of parts for the "heart shaped badge" (£5.50). (http://www.rshelectronics.co.uk/electronicsclubkits.htm)
It looks like the pcb included is veroboard (http://www.verotl.com/node/7): rather too easy to put components/wires into the wrong holes, or cut the wrong track.
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Use a 4022 instead of a 4017 as using the reset pins on the 4017 does not give a smooth changeover on reset. The 4017 is a 10 decade counter whereas the 4022 is an 8 decade counter so for 4 counts just use every other output.
These will drive leds directly and as suggested you could use transistor drivers to boost the output current. Or use a 4016 quad bi-lateral switch followed by relays for even higher power.
Here is a prototype 8 step sequencer I made 3 months ago using a 4022. Please pm me if you would like the schematic and PC diagram.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi262.photobucket.com%2Falbums%2Fii83%2Fbeefake%2Fseq.jpg&hash=c4cf4cb5d7d7fcc3652dcb9858ad6710)
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Would I be able to use a similar device to power electro-magnets, in sequential order? I want to have 4 electo-magnets aranged in a circular pattern on a board. And I want a wheel in the center, with a peice of iron. So eventually, I am trying to build a motor. This may be inefficient, but it is for my little sister's science fair.
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I am trying to build a motor. This may be inefficient, but it is for my little sister's science fair.
A very simple electric motor... http://uk.youtube.com/watch?v=iYlTcOqUnsY&NR=1
The sliver disk the battery is sitting on is a very powerful magnet. (http://www.powermagnetstore.com/)
Warning: Swallowing more than one of these magnets could be fatal (http://edition.cnn.com/2007/US/08/14/toy.victim/index.html).
Even simpler electric motor ... http://uk.youtube.com/watch?v=w2f6RD1hT6Q&feature=related
(How electric motors work (http://uk.youtube.com/watch?v=it_Z7NdKgmY&feature=related))
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This "bristlebot" robot looks like an excellent science-fair project (using motors)...
http://uk.youtube.com/watch?v=rUSTXUis_ys&feature=channel
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@ Onlyinterestednotdevoted.
Yes you could use it but for your application the link that RD gave for the badge would do. It would need a knowledge of electronics to change the reset and add transistor drivers. Also you would have to protect the circuit from back emf by using diodes otherwise the electro magnets will destroy the IC's. Its not such an easy or simple project for a beginner.
What you describe would be inefficient but it would create a rotating magnetic field which you want. 3 electro magnets would do it as it should then act like a 3 phase motor and spin the rotor(wheel).
If its a simple show for younger children (little sister) then this is worth a look at. Not a motor but electronic, visual and fun. You can download the instructions and build your own or buy a kit.
http://www.blinkybug.com/
I like the youtube videos as well RD. [:)]
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Despite being billed as "electro-mechanical" I was disappointed to read that the BlinkyBug (http://www.blinkybug.com/)gers do not move.
The kinetic (and audible) Bristlebots (http://uk.youtube.com/watch?v=rUSTXUis_ys&feature=channel) would get more attention at a science-fair.
The pager/cellphone motor (http://www.73.com/a/0185.shtml) used in the BristleBot costs about $4 or $5.
Could use a sweeping brush instead of a toothbrush for the BristleBot, but a bigger motor will be required ... http://uk.youtube.com/watch?v=XmLn6icXy3Q&NR=1
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"Phase lock loop (PLL)" and "cycle" in DC(AND/OR RECTIFIER for AC) are the lookup you need.
Piezoelectric effect:
http://en.wikipedia.org/wiki/Piezoelectric
when voltage cannot break the NPN or PNP input transfre to the next switch point.
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Is that relevant, nicephotog?
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electronic device to create a pulse.....4 lightbulbs that shine in sequential order.
Phase Lock Loops are the standard way of holding timing for a pulse to occur conjunct with a crystal oscillator.
Crystal oscillators are reliable for their disgnated frequency, that why they are used.
As you well would know, these oscillations are a cycle of rise and fall of amperage lagging to voltage in charge of a capacitor of which the PLL system is standard the world round for holding accuracy of voltage for both the capacitor and the crystals' rating to step up or down all the way to human observable charging actions on light bulbs lasting secons or minutes.
Its inside every peice of computer hardwre as the principle.
So are you designing an electronic circuit or did your fan or heater or toaster have a problem
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PLL? Whatever for?
This is a simple beginner's project. The clock chip can be virtually anything for it to work. The original post was for something what would WORK, not something that would need detailed design. That would be for project number four, perhaps.
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I was still suggesting something simple, e.g. a slow charge non polar capacitor with the pins hooked to a resistor that controls the break down voltage of the base of a transistor so that when the capacitor charges no more because it is finally full it will be enough to do the crude push past the resistor and open the base, of one end of the transistor(the end into the transistor past the base (neg for current direction flow sake)) is hooked to the capacitor side(you need to design that around a PNP or NPN).
Its pretty simple just the same old math hassle to get right and not a PLL.
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What's wrong with a '555 timer'? Every School Project uses one and the application sheet tells you what component values to use.
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Oh!? i see, you just want to use one, but you still have the switching,so you'll need a sequencer.
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I just want to reccommend a device which will work easily as a clock. The 'sequencer' of course, is necessary. I don't think I implied otherwise.