Electronic geekery
sarajoy
Posts: 1,675
Opened up my rear cateye the other day to check batteries - and noticed there are two holes left for a couple more LEDs.
Now it looks like the only difference between mine and the one up is the number of said LEDs.
I work somewhere ideal for finding and adding a couple of new ones - but I'm wondering if anyone's tried it? I did gently try to prise the tiny wee circuit board out with my fingers but it seems fairly firmly fixed.
The only problem I can see is if they program the little chip in there differently for the two models, and so the two new LEDs might never light.
Worth a go, right?
Now it looks like the only difference between mine and the one up is the number of said LEDs.
I work somewhere ideal for finding and adding a couple of new ones - but I'm wondering if anyone's tried it? I did gently try to prise the tiny wee circuit board out with my fingers but it seems fairly firmly fixed.
The only problem I can see is if they program the little chip in there differently for the two models, and so the two new LEDs might never light.
Worth a go, right?
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I really, really know nothing about this but don't you need to solder in the right resistors as well as the LED?0
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Nevermind, found that someone has indeed done it!
http://www.instructables.com/id/Cateye_ ... t_Upgrade/0 -
Not really, as two batteries provide 3V which is what many LEDs happily run at anyway. If we needed to pull down the supply voltage to something lower, then you probably would need them, aye.biondino wrote:I really, really know nothing about this but don't you need to solder in the right resistors as well as the LED?0 -
Hmm, it's possible the supply current is limited though - so I may have to change a resistor anyway... Ack, will find out once I get it in the lab and have a play
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sarajoy wrote:
Not really, as two batteries provide 3V which is what many LEDs happily run at anyway. If we needed to pull down the supply voltage to something lower, then you probably would need them, aye.biondino wrote:I really, really know nothing about this but don't you need to solder in the right resistors as well as the LED?
But you need the resistor in line otherwise there's a a dead short across the battery. LEDs have no resistance, unlike a bulb. That said I 'd expect the existing circuitry to include resistors - cots wise it's cheaper to build the same circuit for all permutations of LEDs.0 -
This might be a good thread for someone to explain to me how LEDs light up
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That's true, so there should be some resistors in there, then. I'm suppsedly an electronic engineer?!
It does mean that putting in 5 LEDs when the circuit expects 3 might mean that all five are independently dimmer than each of the 3 would have been. So might mean a resistor swap-out or addition if there's one per LED... Should be possible though 0 -
An LED is a diode - it passes currently freely in one direction. You'd need to calculate the volt drop for two additional LEDs but in reality I'd expect that the existing 3 run a little too brightly and might blow after 5 years instead of 20 [which works in favour of the manufacturer anyway as you buy more lights], so adding 2 more brings the current across all 5 down closer to the centre of the usable range. What have you got to lose?0
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Just a few mA it seemsChrisInBicester wrote:What have you got to lose?
Certainly the bloke in the tutorial I linked to makes no mention of lessened brightness.
Cool
Sadly I don't think my headlight has room for upgrade (HL-EL135 - three holes, three LEDs)! Is there anything else I can attack with the works' soldering iron, muahahah...0 -
you should be fine adding in extra LEDs. It looks like the LEDs are wired in series so the same current will flow through all of them so you're ok on that front. the only thing to worry about is the voltage drop which will increase to roughly +1.2v (0.6 for each LED) so the batteries might not have enough power to drive the circuit. but luckily there is a small chip that should boost the voltage and perform the various different blinking modes. this chip is most likely the same chip in the model up (so manufacturer can save costs) so is more than capable of driving all 5 leds.
so to summarize you'll be fine!
sorry if i've sent you all to sleep you can wake up now.
(ps according to a piece of paper I have I am a Master of Electronics so I hope im not talking rubbish)0 -
Sounds good, jairaj.
I'm an electronics batchelorette if you like - I ought to know better what I'm on about!
Yeah I was hoping the same for the chip. Seeing as it worked on that bloke's tutorial it should be OK - I daresay shining it into my face afterwards will happily tell me if it's bright enough or not!
I expect a bit of battery-life shortening but I don't mind that so much 0 -
Go on, explain it to me, please? Between you you have the knowledge to form an exciting electronics start up with a small injection of venture capital so I'm sure you can explain how an LED works!0
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biondino wrote:Go on, explain it to me, please? Between you you have the knowledge to form an exciting electronics start up with a small injection of venture capital so I'm sure you can explain how an LED works!
lol in how much detail would you like to know? I can give you a basic understanding so you can make pretty lighty up things of your own or I can give you proper in depth knowledge of the processes that happen at the atomic level? 0 -
Well, in a massively simplistic mind (i.e. mine) it feels easier to humanise objects! This might sound REALLY patronising now if you read on - but I honestly go through my working life explaining how bits and pieces want to do this, that or t'other and what makes them 'happy' and how the program crashing is due to some variable going "Erp! Don't like this!"
So anyway, you have your common or garden diode where during manufacture, one side is charged positively, and the other side negatively. Free electrons (themselves negatively charged) are drawn towards the positive side as they'd like to cancel out the imbalance and keep everyone neutral and happy, man.
As they escape their negativity and fly into their 'hole' on the positive side, they let out a happy squeal of energy, which comes out as a photon, or a 'wave/particle' of light (but which it is? Another kettle of fish, that one).
I tend to think of positive/negative levels or voltage drops as differences in height... We get a load of kinetic energy jumping off a wall, often with a squeal as well - but don't feel much tireder for having done so - essentially free energy... But batteries/food give us the energy to get to the top of that wall in the first place.
So, the more electrons fly through, the brighter the LED. Until too many go through at once and the poor thing burns itself out... which is why we'd need the limiting resistor, otherwise it'll just pull and pull at the battery until either it pops or the battery goes flat.
(typo corrected, cheers jairaj!)0 -
4/5 you dropped a mark for stating that a proton is emitted should be a photon
other than that pretty good. As you said its essentially just electrons going from a high energy state to a lower one and the energy they loose gets converted into light!0 -
Oh bum, did I? What a typo.
You said 'loose' instead of 'lose' though so I guess we're even
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That's possibly the best layman's explanation of LEDs I've ever seen... Well done.sarajoy wrote:So anyway, you have your common or garden diode where during manufacture, one side is charged positively, and the other side negatively. Free electrons (themselves negatively charged) are drawn towards the positive side as they'd like to cancel out the imbalance and keep everyone neutral and happy, man.
As they escape their negativity and fly into their 'hole' on the positive side, they let out a happy squeal of energy, which comes out as a photon, or a 'wave/particle' of light (but which it is? Another kettle of fish, that one).
I tend to think of positive/negative levels or voltage drops as differences in height... We get a load of kinetic energy jumping off a wall, often with a squeal as well - but don't feel much tireder for having done so - essentially free energy... But batteries/food give us the energy to get to the top of that wall in the first place.
So, the more electrons fly through, the brighter the LED. Until too many go through at once and the poor thing burns itself out... which is why we'd need the limiting resistor, otherwise it'll just pull and pull at the battery until either it pops or the battery goes flat.
(typo corrected, cheers jairaj!)0 -
It's excellent, thank you very much! I did an Open University short course on astrophysics that spent an age talking about the various energy levels of particles and how they emitted photons but it never actually occurred to me to make the connection, oops.0
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Very kind of youwhyamihere wrote:That's possibly the best layman's explanation of LEDs I've ever seen... Well done. Doesn't seem to make me any better an engineer though!
I remember once explaining the principles of voltage and current to a friend by equating it all to rivers and paddle-wheels. The voltage varied with the height of a waterfall, the current varied with, uh, current - and power was how well that stream could turn a paddle-wheel... The higher the waterfall, the bigger a wheel (or a larger number of wheels) you could fit under it to get more power out. Resistance I guess then became the inertia of the wheel, so that you'd lose a little power due to things being imperfect and the wheel's axel maybe being a little rusty...
... I'll get my coat
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lol thats exactly how I think of it too!!
I find it works very well in most situations.0 -
If you don't mind I'll be plagiarising those if/when I do some work experience teaching physics next year.0
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Of coursewhyamihere wrote:If you don't mind I'll be plagiarising those if/when I do some work experience teaching physics next year.
Gets a bit messy when you start trying to talk about capacitors (dams?), inductors (errr...) and anything else that goes towards the higher frequencies... I guess it kinda works, and then the vapour from the water flying out due to being pushed and pulled all the time could be power leakage... Got me started now. I like this kindof stuff, I sort of fancy myself as a physics teacher when I get older...0 -
sarajoy wrote:
Very kind of youwhyamihere wrote:That's possibly the best layman's explanation of LEDs I've ever seen... Well done. Doesn't seem to make me any better an engineer though!
I remember once explaining the principles of voltage and current to a friend by equating it all to rivers and paddle-wheels. The voltage varied with the height of a waterfall, the current varied with, uh, current - and power was how well that stream could turn a paddle-wheel... The higher the waterfall, the bigger a wheel (or a larger number of wheels) you could fit under it to get more power out. Resistance I guess then became the inertia of the wheel, so that you'd lose a little power due to things being imperfect and the wheel's axel maybe being a little rusty...
... I'll get my coat
You want the "Hydraulic analogy (wiki)"
the water wheel is actually more like an inductor*, takes tim for "flow" to get it up to speed, when it has "no" resistance, and then tries to keep the flow going when it changes. (The friction in the wheel could also be resistance).
A narrow pipe is a resistor.
*any curve of metal, or coil, so very important in filament bulbs or motors/dynamos, amongst other things.0
