Friends,
There is no frustration section so it has to be here!!!
This is the scenario, please read all the way through before offering any replies!
Please do not inform me that you have NEVER had any problems, I need answers!
(1) The manufacturer of my Point Position Indicators recommend that 12 volts DC is the best supply. (Purchased plug in to mains transformer that has an output of 12 volt DC @ 1 Amp)
(2) Purchased 65 pre-wired 3 mm Blue LED's. (Need 34: extras for spares)
(3) Tested each LED BEFORE fitting to console with a blob of hot melt glue (Suggested by other members)
(4) Retained the 20 Cm cable length that came with the LED's and soldered the (C1 negative and the C2 Positive) together as suggested by our mutual friend Malc. (Obviously not in the same loom!)
((ADDENDUM) Following one reply: The LED's were purchased C/W Resistors and 20 CM of wire)
(5) Tested the arrangement using the same method as previous pre-mounting test. (5) LED's didn't light?
(6) Removed wiring to those LED's affected, re-tested, dead as Dodo's!
(7) Replaced faulty LED's after testing, this time others failed, not the original failures!
(Eight) Removed all the soldered joints and tested ALL the LED's, 99% failure!
(9) Replaced ALL the LED's after testing that they ALL worked individually! RE-TESTED!
(10) Failure on (Eight) LED's.
(11) Gave up in utter frustration!!!
Is this a normal situation or am I doing something I shouldn't be doing, like getting involved in the first place, feel like giving up the whole idea of model railways!
Constructive answers only PLEASE! Peter.
Peter try swapping the wires over to the LED. Might work!
Hi
You do have a resistor in series with the LEDs dont you?
Cheers
Paul
Quote from: Bealman on July 03, 2015, 11:41:36 AM
Peter try swapping the wires over to the LED. Might work!
Thank you George, tried that didn't change anything. Forgot to include that information! (as usual)
Quote from: PaulCheffus on July 03, 2015, 11:43:01 AM
Hi
You do have a resistor in series with the LEDs dont you?
Cheers
Paul
Paul, yes the pre-wired LED's come complete with resistors. Peter
More info needed, I am afraid - without that we are running blind.
Which PPI manufacturer and which specific product? Same for the LEDs (a link to the webpage if an Ebay supplier?) A photo of how you have wired it?
Mate I was trying to avoid a convoluted answer which I know you don't want or need. :thumbsup:
Sounds like there is some polarity getting changed in your wiring somewhere.
George
A couple of questions Peter.
When you tested the LEDs, did you use the 12v supply you were using for the PPI?
Does the PPI have its own LEDs on and do they light?
As Malc askes, have you tried powering the LEDs directly from either the 12V supply or a 9V battery?
What is the make and model of the Point Position Indicator?
If they work then I'd guess that the point position indicator you have has current limiting resistors built into the circuit already. By adding the extra ones already connected to the LEDs you've ended up limiting the current so much that there's not enough power getting to the LEDS to light them. The chances are the point position indicator board is actually running at 5V (via a built in regulator) which will make matters worse.
Happy modelling.
Steven B.
Quote from: Steven B on July 03, 2015, 12:40:38 PM
As Malc askes, have you tried powering the LEDs directly from either the 12V supply or a 9V battery?
What is the make and model of the Point Position Indicator?
If they work then I'd guess that the point position indicator you have has current limiting resistors built into the circuit already. By adding the extra ones already connected to the LEDs you've ended up limiting the current so much that there's not enough power getting to the LEDS to light them. The chances are the point position indicator board is actually running at 5V (via a built in regulator) which will make matters worse.
Happy modelling.
Steven B.
The problem is that the LEDs are blowing, even with the built in resistor, not that they aren't illuminating.
Quote from: Malc on July 03, 2015, 01:47:57 PM
Quote from: Steven B on July 03, 2015, 12:40:38 PM
As Malc askes, have you tried powering the LEDs directly from either the 12V supply or a 9V battery?
What is the make and model of the Point Position Indicator?
If they work then I'd guess that the point position indicator you have has current limiting resistors built into the circuit already. By adding the extra ones already connected to the LEDs you've ended up limiting the current so much that there's not enough power getting to the LEDS to light them. The chances are the point position indicator board is actually running at 5V (via a built in regulator) which will make matters worse.
Happy modelling.
Steven B.
The problem is that the LEDs are blowing, even with the built in resistor, not that they aren't illuminating.
Could it be that Peter is connecting the led's the wrong way round and there is sufficient reverse voltage/current to blow them? Just a thought.
:beers:
Quote from: Jonny on July 03, 2015, 01:54:50 PM
This may sound silly but the pre wired resistors haven't been put on the wrong leg (ie neg) and are getting straight 12v thus when checking with 12v supply popping them straight off brfore you fit them Peter.
Hi
Doesn't matter which leg you put the resistor in the effect will be the same.
Cheers
Paul
Peter,
Sorry but I have struggled to follow exactly what you have done.
However, generally LEDs are fairly bullet proof and the only thing that really destroys them is too much current. Reversing the wires should not blow them.
I would initially test the leds on something safe, such as a 9v battery. This should be safe if the led has a correct led in series for 12v. The leds should still light albeit slightly dim but should be well bright enough to see it is lit.
If you can verify you have some working leds using a 9v battery then could you do a bit of a sketch how you are connecting them to the point position indicators. Also what make are the point position indicators?
Steve
Quote from: Jonny on July 03, 2015, 02:46:02 PM
In all theory connection the wrong way round should not harm them as leds will only work one way round unlike conventional bulbs.
(Peter ignore this)..Jonny, just for your info led's, just like other diodes, have a maximum allowed reverse voltage. This is normally specified at around 4 or 5V. If exceeded the led will blow. Do a google on led reverse breakdown to find out more.
:beers:
Most of the ebay sold leds sold with pre soldered resistors are covered in opaque heatshrink so you have to rely on the seller getting the correct value of resistor.
If it is the block signalling indicator then the wiring diagram suggests using only one resistor for a pair of leds, and suggests the cathodes of each led are connected together then to a 1K resistor. The other side of the 1K resistor then goes to the supply common (or negative).
http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi1 (http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi1)
However the leds with pre soldered resistors can still be used. Just wire the anode (+ lead) to the ouptut from the board and all the cathodes (- lead) to the common terminal.
Steve
Quote from: Steve.T on July 03, 2015, 04:34:36 PM
Most of the ebay sold leds sold with pre soldered resistors are covered in opaque heatshrink so you have to rely on the seller getting the correct value of resistor.
If it is the block signalling indicator then the wiring diagram suggests using only one resistor for a pair of leds, and suggests the cathodes of each led are connected together then to a 1K resistor. The other side of the 1K resistor then goes to the supply common (or negative).
http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi1 (http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi1)
However the leds with pre soldered resistors can still be used. Just wire the anode (+ lead) to the ouptut from the board and all the cathodes (- lead) to the common terminal.
Steve
Steve - I think we established in a previous thread that Peter has th PPI 4 which, from memory, has a different arrangement.
:beers:
Oh, okay, sorry.
Then ignore my last post then.
Would I be right in then thinking the PPI 4 does not require any series resistor.
Steve
Peter,
Hope you get there in the end.
If you want to try some regular green and red leds then pm me your address and I can post a few for you to try, then if that works you are confident to order the rest.
If you need them with wires soldering onto them let me know.
Steve
Friends,
Thank you for all your replies, as usual, it appears that I have omitted tons of information!
(1) I am NOT fitting the PPI's, ONLY the LED's into the top panel of my console. The PPI's will not be installed until ALL the connections to switches, LED's etc are up and running following the PPI manufacturer instructions. (Block Signalling PPI4 DC)
(2) The PPI manufacturer only recommended the use of a 12 volt DC supply instead of my own 16 volt AC supply.
(3) I have to assume from the advertisers information that the resistors are suitable for use with 12 volts DC. (I purchased the LED's from several suppliers on Ebay so perhaps I have done a doodoo in my own nest, as usual I was trying to spend the least amount of money?)
(4) Question: If I test the LED's at 9 volts DC and then raise the voltage to 12 in situ, am I not likely to have the same result but with even more hassle involved in removing them again?
(5) According to an email from Steve Heaton @ Block Signalling, having resistors already fitted to the LED's will make no difference at all!
I apologise and hope that this clarifies SOME of the unmentioned problems.
Peter.
Peter, just to confirm. You are not connecting the PPI yet. You are connecting the short leg (cathode or side with the flat) together on one set of LEDs. This common connection will go to C1-. You do the same with the other set of LEDs and this will eventually go to C2-. If you connect your 12v- to the common wires and the touch the other legs of the LEDs to the 12v+ in turn, they should light.
[smg id=22373 type=preview align=center width=400]
You need one of these, Peter! One of the best bits of test gear I ever bought. It's especially useful if you have a bunch of clear leds and want to find out what colour they light up before you hard wire them into a circuit.
Quote from: Malc on July 03, 2015, 10:31:00 PM
Peter, just to confirm. You are not connecting the PPI yet. You are connecting the short leg (cathode or side with the flat) together on one set of LEDs. This common connection will go to C1-. You do the same with the other set of LEDs and this will eventually go to C2-. If you connect your 12v- to the common wires and the touch the other legs of the LEDs to the 12v+ in turn, they should light.
Malcolm, thank you.
There is no short leg and no long leg (Pre-wired LED's) just a Red wire (With resistor) and a Black wire, if I offer one of the wires from the feed to the wrong wire the LED does not light but the other way round it does!
My total knowledge!I have been doing some digging on the 'net before our crappy laptop seized solid!
240 volt AC transformers that merely plug into the mains and give out 12 volts DC are, as I understand it, uncontrolled (
Meaning that the output varies???), if that is the case then the one I have bought is likely to give a surge, Yes/No??, which could be blowing the LED's? (The transformer in question cost me £4.99 on Ebay, Made in China)
Should I therefore bite yet another bullet and consider a more expensive transformer from one of the model railway suppliers?
Warmest regards, Peter.
If your answer is Yes, which one should I be considering?
Hi Peter, you mean unregulated rather than uncontrolled. I use something like this.
https://www.amazon.co.uk/dp/B00ENZUQO8/ref=cm_sw_r_awd_UB6LvbES0T9BP (https://www.amazon.co.uk/dp/B00ENZUQO8/ref=cm_sw_r_awd_UB6LvbES0T9BP)
I don't know how much current your PPI will draw, but it shouldn't be much.
I use several like this for lights, arc welders etc
Quote from: Malc on July 04, 2015, 10:31:25 AM
Hi Peter, you mean unregulated rather than uncontrolled. I use something like this.
https://www.amazon.co.uk/dp/B00ENZUQO8/ref=cm_sw_r_awd_UB6LvbES0T9BP (https://www.amazon.co.uk/dp/B00ENZUQO8/ref=cm_sw_r_awd_UB6LvbES0T9BP)
I don't know how much current your PPI will draw, but it shouldn't be much.
I use several like this for lights, arc welders etc
Thank you I will keep that one in mind!
Would this one be of any use?
http://www.ebay.co.uk/itm/290883688146?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.co.uk/itm/290883688146?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Peter.
It might be a little on the low side for current. 1amp should be OK though. It does need wiring up to the mains. It is really meant for those under cupboard LED lights and would be wired into the ring main.
Peter
It seems that your LEDs are blowing because you are trying to pass too much current through them. This is pretty much the consensus of this thread. LEDs have a maximum current rating - small LEDs will have a smaller current rating than larger ones because they have finer wires and are less able to dissipate excessive heat. We need to know what the maximum current rating is in order to calculate the size of resistor required. The voltage drop across an LED is colour dependent and might range from 2 V (red) up to more than 3 V (blue). For LEDs run off a 12V supply, let's say 3 V is dropped across the LED itself leaving 9 V to be dropped across the resistor. If the LED is rated as having a maximum current of 10 mA say, then the resistor required to limit the current to 10 mA (= 0.01A) is = 9 / 0.01 = 900 ohms. If the LEDs being used have a maximum current of somewhat less than 10 mA, then a 1000 ohm resistor will not be enough to limit the current and prevent the LED from blowing up.
My electronics catalogue lists 3 mm LEDs mostly with a maximum current of 20 mA or more. Going through the resistance calculations for these suggests that a 500 ohm resistor would be plenty large enough to limit the current for these if a 12 V supply is used to run them. Peter, can you tell us what the maximum current rating is on your LEDs, please.
Webbo
Quote from: Webbo on July 05, 2015, 05:09:39 AM
It seems that your LEDs are blowing because you are trying to pass too much current through them. T
I don't think that is the problem Webbo. The PPI4 instructions show the LED's connected with no resistor added. So the current must be limited on the PPI.
http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc (http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc)
If the LED's were running at too high a current they would be extremely bright until they blow. I'm sure Peter would have noticed that.
The most likely problem, in my opinion, is that the LED's have been connected the wrong way round. There seems to have been some confusion in previous posts about which lead the resistor is connected in - I'm not sure if that has been resolved.
I still think the best solution, if Peter thinks he is capable of it, is to use plain LED's as described in the PPI4 instructions.
If this is practical for Peter then he could just wire up one set of LED's and see if they work reliably. If not then we have to think again.
Regards
:beers:
Yes, I understand that there is a current limiting resistor in the PPI4 of 1000 ohms. I suppose that what I'm suggesting is that Peter may have bought LEDs with maximum allowable currents that are less than 10 mA in which case 1000 ohms would not be enough on a 12 V supply. Seems unlikely for 3 mm LEDs but possible. And I agree that he would see the LEDs burn brightly for a short period before giving up the ghost if excess current were the problem (sort of like a supernova).
Webbo
Quote from: Only Me on July 05, 2015, 09:22:49 AM
Hes not using the ppi at the moment accordinng to his replies so my original (unanswered post) still thinks the resistors are the issue.
Paul, the resistors are an unknown since I have chucked the blown ones!
I have tried removing the sheathing or whatever it is on one of the others and only managed to get a bit off before slicing my finger!
I am thinking of cutting my losses and purchasing a whole set of new from one supplier, preferably in the UK as I have hinted in another thread.
http://www.ngaugeforum.co.uk/SMFN/index.php?topic=28560.msg314919#msg314919 (http://www.ngaugeforum.co.uk/SMFN/index.php?topic=28560.msg314919#msg314919)
I would appreciate your thoughts on those LED's before I go any further with my originals?
Warmest regards, Peter.
Quote from: Only Me on July 05, 2015, 09:22:49 AM
Hes not using the ppi at the moment accordinng to his replies so my original (unanswered post) still thinks the resistors are the issue.
Ok - you're right about not using the PPI - missed that (too much information!!)
What I don't understand is that assuming Peter used the same test voltage before and after he mounted the LED's, why would they be fine to start with and then fail after mounting them? Unless he accidentally got the power supply reversed?
Running out of ideas here.
Regards
:beers:
I'm getting a bit annoyed with all this and I tend to think Peter might be too.
LEDs are lights, for hecks sake. They are diodes that just happen to turn electrical energy into light, with DC current going in the correct direction.
We can always go back to incandescent light indicators, with no polarity problems but needing a bank of relays to switch 'em.
:beers: George
Quote from: Bealman on July 05, 2015, 11:19:30 AM
I'm getting a bit annoyed with all this and I tend to think Peter might be too.
LEDs are lights, for hecks sake. They are diodes that just happen to turn electrical energy into light, with DC current going in the correct direction.
You're right George, this ought to be a very simple problem to solve. Unfortunately we (the posters in this thread) are not in a position where Peter can take some basic measurements so we can confirm what is going on. Many of us here with a few minutes and a multimeter could solve this problem quite easily.
We're all trying to help - but we are really only guessing at the moment.
:beers:
Quote from: austinbob on July 05, 2015, 08:31:27 AM
Quote from: Webbo on July 05, 2015, 05:09:39 AM
It seems that your LEDs are blowing because you are trying to pass too much current through them. T
I don't think that is the problem Webbo. The PPI4 instructions show the LED's connected with no resistor added. So the current must be limited on the PPI.
http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc (http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc)
If the LED's were running at too high a current they would be extremely bright until they blow. I'm sure Peter would have noticed that.
The most likely problem, in my opinion, is that the LED's have been connected the wrong way round. There seems to have been some confusion in previous posts about which lead the resistor is connected in - I'm not sure if that has been resolved.
I still think the best solution, if Peter thinks he is capable of it, is to use plain LED's as described in the PPI4 instructions.
If this is practical for Peter then he could just wire up one set of LED's and see if they work reliably. If not then we have to think again.
Regards
:beers:
Hi
Why does it matter which lead the resistor is in it will work whether it is connected to the positive or negative side. What does matter is which way around the led is connected to the supply.
If you mean that the convention is to put the resistor in the positive side and this is how they have been tested then a quick reversal of the supply should show this. I have never killed an LED by reversing the supply through it provided there is a resistor in series of an adequate size. I tend to use 1K for 12v
Cheers
Paul
Quote from: PaulCheffus on July 05, 2015, 12:46:00 PM
Quote from: austinbob on July 05, 2015, 08:31:27 AM
Quote from: Webbo on July 05, 2015, 05:09:39 AM
It seems that your LEDs are blowing because you are trying to pass too much current through them. T
I don't think that is the problem Webbo. The PPI4 instructions show the LED's connected with no resistor added. So the current must be limited on the PPI.
http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc (http://www.blocksignalling.co.uk/index.php/points-position-indicator-ppi4-dc)
If the LED's were running at too high a current they would be extremely bright until they blow. I'm sure Peter would have noticed that.
The most likely problem, in my opinion, is that the LED's have been connected the wrong way round. There seems to have been some confusion in previous posts about which lead the resistor is connected in - I'm not sure if that has been resolved.
I still think the best solution, if Peter thinks he is capable of it, is to use plain LED's as described in the PPI4 instructions.
If this is practical for Peter then he could just wire up one set of LED's and see if they work reliably. If not then we have to think again.
Regards
:beers:
Hi
Why does it matter which lead the resistor is in it will work whether it is connected to the positive or negative side. What does matter is which way around the led is connected to the supply.
If you mean that the convention is to put the resistor in the positive side and this is how they have been tested then a quick reversal of the supply should show this. I have never killed an LED by reversing the supply through it provided there is a resistor in series of an adequate size. I tend to use 1K for 12v
Cheers
Paul
It doesn't matter Paul. It's just they were trying to work out the polarity of the led (the connections being hidden by sleeving) by the location of the resistor. Not my sugestion- just an observation.
:beers:
Peter,
I would agree with what has already been said above.
Unless there is fault with the China made power supply it should be fine.
Nothing against China in anyway as I would think 90% are made there anyway - but sometimes you do get faulty cheap items from Ebay - I actually had one of this type of supply that was faulty but in that it just did not work at all.
If you do have a multimeter it would be useful to check it has somewhere about 12V DC output (according to label +ive is the inner part of the plug). Sorry but in all the messages I cannot remember if you said you had a multimeter or not.
The LEDs also look fine.
But I would still test them on a 9v battery first and then you are happy the leds work. They should easily be bright enough to see they are lit but dimmer than normal (try in a darkish room is you find it difficult to see) and that if they consequently blow (I do hope not!) then it was not the fault of the LED but whatever you are connecting it to.
Steve
Peter,
Sorry if you have already answered this in other threads.
On the power supply have you cut the plug off the end and stripped back the wires or have you bought a socket that fits the plug?
The reason for asking is that these plugs and sockets have a huge range of diameter of the inner socket and also in the actual length of the outer spindles. It is real easy to have a plug and socket that appears to fit together fine but there is little, or no, contact between the inner part and can give intermittant contact. The result is a plug and socket that gets hot due to a high resistance contact and delivers very little power.
Steve
Quote from: Steve.T on July 05, 2015, 01:10:08 PM
Peter,
Sorry if you have already answered this in other threads.
On the power supply have you cut the plug off the end and stripped back the wires or have you bought a socket that fits the plug?
The reason for asking is that these plugs and sockets have a huge range of diameter of the inner socket and also in the actual length of the outer spindles. It is real easy to have a plug and socket that appears to fit together fine but there is little, or no, contact between the inner part and can give intermittant contact. The result is a plug and socket that gets hot due to a high resistance contact and delivers very little power.
Steve
The problem is, as Peter stated, not that the LEDs don't glow, they stop working and are dead.
Peter, if the only thing you are doing is hot gluing them in place, stop doing it. They obviously don't like it up 'em. The best approach to mounting I found, was to but some bezels. The heat from the glue must be killing your LEDs. @petercharlesfagg (http://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=2262)
Quote from: Malc on July 05, 2015, 01:43:15 PM
The problem is, as Peter stated, not that the LEDs don't glow, they stop working and are dead.
Peter, if the only thing you are doing is hot gluing them in place, stop doing it. They obviously don't like it up 'em. The best approach to mounting I found, was to but some bezels. The heat from the glue must be killing your LEDs. @petercharlesfagg (http://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=2262)
Malcolm, this is something that I too have begun wondering about!
I have bezels but the LED's do not stay in them when I fit them! They do not snap into place and I cannot retro-fit the little plastic grommets that lock them in place!
The only recourse I have is to use tape or Blu-tack but it would have been better to have purchased LED's with the Chrome bezels already fitted but of course the costs rear their ugly heads again!
As it is, I am ditching the LED's that were cheap from China and I shall purchase new from the company in Yorkshire. The LED's from there may also be from China but I can go back to the supplier to complain if anything goes wrong!
Warmest regards Peter.
Quote from: petercharlesfagg on July 03, 2015, 11:29:39 AM
(4) Retained the 20 Cm cable length that came with the LED's and soldered the (C1 negative and the C2 Positive) together as suggested by our mutual friend Malc.
Have we all got the stamina to revisit this one from Peter in his very first post ?
If I remember right ( bearing in mind I dont have experience of this PPI but I did 'do' electronics for many decades after the dinosaurs lol! ) so I may have forgot a detail and I have not the stamina to go back and track it down, some of you youngsters can do that ;) :-
I think C1 and C2 were, respectively, the common returns for each of the two groups of LEDs ( the green ones and the red ones, but in Peters case what should be the "Group 1 Blue" and "Group 2 Blue", route set and route not set or summat like that )
In which case negative and positive for C1 and C2 have no relevance.
In view of the other misunners on the meaning of 'in-line'
is it worth re-exmining if what Peters implementation of what he thought Malc meant is the same as what malc infact meant,, if you see what I mean ?
I think there is room for a boobo somewhere there, it has been troubling me for quite some days now !
At this stage, Peter hasn't connected anything to the PPI. He has just connected the common legs together and hot glued the LEDs into place. So we suspect the glueing has stuffed the LEDs. They just don't like getting warm.
Quote from: Malc on July 05, 2015, 11:00:27 PM
At this stage, Peter hasn't connected anything to the PPI. He has just connected the common legs together and hot glued the LEDs into place. So we suspect the glueing has stuffed the LEDs. They just don't like getting warm.
I know I have been watching, you say "all the common legs", he is talking all the C1negs and C2pos, are you sure you(we) are talking the same language ? we need diagrams but he cant draw them :(
I just invited consideration of what Peter may have been on about in C1 negative and C2 positive you see. It dont connect with what I understood you woz on about. (in case the hot of his thingumy isnt as hot as yours ?! )
There are, all through these threads, a disconnect between what those 'in the know' mean by a phrase and what Peter understands the terms to mean , , u c ? (see the other "in-line" thread, oh forget that I already said it ! )
As I said, have we the stamina for,
obviously not,,
so I'll butt out again.
:(
Quote from: Malc on July 05, 2015, 11:00:27 PM
So we suspect the glueing has stuffed the LEDs. They just don't like getting warm.
Hot glue won't get any way near heating from soldering so not a consideration.
CFJ
Peter,
1. Supply Voltage
Unregulated 12V DC 1A should supply about 12V at 1A, depending on construction the power supply may be up to 18V or more without a load. Always feed electronics through a voltage regulator if the circuit doesn't have one.
2. Incorrect resistor to limit current through LED.
If you have a multimeter ( of course you do) you can measure the resistance by connecting one probe to the bare wire and one to the leg of the led, obviously the one with the resistor (easy if you have probes with points) but not connected to the power supply. You don't have to strip the whole piece of insulation.
3. Zzzzap
Don't let the hot-glue gun nozzle contact the leads on the led, probably some nice stray voltages from 240V line. Super glue (gap filling kind) works ok for mounting also.
4. Reverse voltage
Have only lost a few to wiring up in reverse with 12V to 15V.
Test a couple of them with the 9V then the power supply before installing. Will tell you if voltage is a problem.
CFJ
Quote from: NinOz on July 06, 2015, 02:16:35 AM
Peter,
1. Supply Voltage
Unregulated 12V DC 1A should supply about 12V at 1A, depending on construction the power supply may be up to 18V or more without a load. Always feed electronics through a voltage regulator if the circuit doesn't have one.
2. Incorrect resistor to limit current through LED.
If you have a multimeter ( of course you do) you can measure the resistance by connecting one probe to the bare wire and one to the leg of the led, obviously the one with the resistor (easy if you have probes with points) but not connected to the power supply. You don't have to strip the whole piece of insulation.
3. Zzzzap
Don't let the hot-glue gun nozzle contact the leads on the led, probably some nice stray voltages from 240V line. Super glue (gap filling kind) works ok for mounting also.
4. Reverse voltage
Have only lost a few to wiring up in reverse with 12V to 15V.
Test a couple of them with the 9V then the power supply before installing. Will tell you if voltage is a problem.
CFJ
Thank you for your reply to my queries.
(1) I had assumed, being a lay person, that a transformer reducing 240 volt AC to 12 volt DC would be a constant flow of electricity at that rate? This "voltage regulator" confuses matters yet again! I studied the results from a Google search and there are thousands to choose from and I haven't the foggiest idea which one, if any, I should buy! (Back to square one!)
(2) Yes I have a multi-meter but I cannot understand all the jargon in the instructions! I ONLY use it to test if I am getting a connection by the needle moving, the rest is a mystery! As for removing the shrouding on an LED, I gave up and chucked it in the bin! I trust that the suppliers of LED's who state that their products can be used with 12 volts DC and have resistors and wires fitted, because I know no different! I cannot solder those pieces myself because I shake so violently when trying to concentrate on small areas, my soldering nickname is Mr Blobby!
(3) With reference to the last paragraph, I HAD to rest the glue gun on something, probably the LED to stop me spreading glue over a wider area due to my shaking hands! It is EXTREMELY likely that I DID rest on the LED's , cables, resistors etc! I have ordered a a small tube of silicone sealant instead.
(4) Reverse voltage I do not understand! If I connect up the LED the wrong way it doesn't work, if it is the correct way around it does, job done! I WILL be testing EVERY LED BEFORE fitting, just as I did the first, second and third time!
I REALLY appreciate your helpful comments, regards, Peter.
LEDs are cheap throw away devices like ballpoint pens, unfortunately (not getting into environment discussion here), so I concur with earlier posts that the cause needs to be addressed - LEDs are cheap and easily replaced, but there's no point if the power supply issue is not sorted.
Quote from: petercharlesfagg on July 06, 2015, 08:50:43 AM
(4) Reverse voltage I do not understand! If I connect up the LED the wrong way it doesn't work, if it is the correct way around it does, job done!
If you connect the LED to an AC supply it will get forward voltage (which will cause it to light) for half the cycle and reverse voltage for the other half. (Think of the
Alternating
Current as switching between + and - the whole time.) If the reverse voltage is too high the LED will blow.
Quote from: keithfre on July 06, 2015, 01:48:09 PM
If you connect the LED to an AC supply it will get forward voltage (which will cause it to light) for half the cycle and reverse voltage for the other half. (Think of the Alternating Current as switching between + and - the whole time.) If the reverse voltage is too high the LED will blow.
True. :thumbsup:
Strictly speaking you should have another diode across the led in reverse to the led (cathode to anode or -ive to +ive) this can be a plain diode or another led, but it needs to use the same current limiting resistor. This protects the led from the reverse.
Typically the max reverse voltage is about 5V, and on 12V it can get higher than that in reverse (but briefly each cycle) as the limiting resistor does not act in the same way.
However, I have seen circuits for 9 and 12v ac with led & resistor without the added diode and I have had no failures.
Maybe because the reverse voltage is transient it works but strictly speaking it does need this diode you are right.
But I did not want to complicate things anymore than necessary.
I think we are all guilty of wanting to help Peter so much but as we all keep adding comments,
like mine now :-X, the threads get too long and maybe over complicate things for Peter.
Quote from: Bealman on July 04, 2015, 12:40:04 AM
[smg id=22373 type=preview align=center width=400]
You need one of these, Peter! One of the best bits of test gear I ever bought. It's especially useful if you have a bunch of clear leds and want to find out what colour they light up before you hard wire them into a circuit.
@Bealman (http://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=255)
That looks a neat bit of kit, George, but the nearest I've seen is at Maplins for £9.99 and it looks positively 'clunky' compared to yours ::)
Did you source yours in Oz please?
(P.S. Surprised you haven't commented on Rohan Dennis's performance on the 1st day of the Tour de France!)
Quote from: MalcolmAL on July 05, 2015, 11:21:20 PM
Quote from: Malc on July 05, 2015, 11:00:27 PM
At this stage, Peter hasn't connected anything to the PPI. He has just connected the common legs together and hot glued the LEDs into place. So we suspect the glueing has stuffed the LEDs. They just don't like getting warm.
I know I have been watching, you say "all the common legs", he is talking all the C1negs and C2pos, are you sure you(we) are talking the same language ? we need diagrams but he cant draw them :(
I just invited consideration of what Peter may have been on about in C1 negative and C2 positive you see. It dont connect with what I understood you woz on about. (in case the hot of his thingumy isnt as hot as yours ?! )
There are, all through these threads, a disconnect between what those 'in the know' mean by a phrase and what Peter understands the terms to mean , , u c ? (see the other "in-line" thread, oh forget that I already said it ! )
As I said, have we the stamina for,
obviously not,,
so I'll butt out again.
:(
Please accept my apologies I got the whole description wrong!
C1 and C2 are negative!
Please remember you are trying to help someone who has difficulty with being Positive about anything Negative!
Corrected, Peter.
Quote from: newportnobby on July 06, 2015, 05:16:54 PM
That looks a neat bit of kit, George, but the nearest I've seen is at Maplins for £9.99 and it looks positively 'clunky' compared to yours ::)
Did you source yours in Oz please?
(P.S. Surprised you haven't commented on Rohan Dennis's performance on the 1st day of the Tour de France!)
Here you go Mick, if you are not in a rush for it you can get one from China for £1.51 which will take 3 - 4 weeks to get here:
http://www.ebay.co.uk/itm/Mini-LED-Tester-Box-Portable-Test-Light-emitting-Diode-Bulb-Lamp-9V-2-150mA-WE2U-/171749782393?pt=LH_DefaultDomain_3&hash=item27fd15b379 (http://www.ebay.co.uk/itm/Mini-LED-Tester-Box-Portable-Test-Light-emitting-Diode-Bulb-Lamp-9V-2-150mA-WE2U-/171749782393?pt=LH_DefaultDomain_3&hash=item27fd15b379)
or
You can spend your money recklessly, pay £2.99 and get it from the UK:
http://www.ebay.co.uk/itm/Mini-2-150mA-LED-Bulb-Light-Lamp-Tester-Test-Checker-Box-Tool-With-9V-Battery-/371337947805?pt=LH_DefaultDomain_3&var=&hash=item5675776a9d (http://www.ebay.co.uk/itm/Mini-2-150mA-LED-Bulb-Light-Lamp-Tester-Test-Checker-Box-Tool-With-9V-Battery-/371337947805?pt=LH_DefaultDomain_3&var=&hash=item5675776a9d)
cheers John.
Thanks John, but with Lawrence's help I reckon we've found the one George has, and it appears to have a better spread of power outputs so I'll be going for this one.............
http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD (http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD)
Item AA0274
Quote from: scotsoft on July 06, 2015, 06:50:50 PM
or
You can spend your money recklessly,
Wot !
Point of order sir : members of this forum 'reckless', shirley not ?
or maybe there is an oxymoron lurking ? ;D :laugh3: :laugh: :bounce:
Quote from: newportnobby on July 06, 2015, 09:18:46 PM
Thanks John, but with Lawrence's help I reckon we've found the one George has, and it appears to have a better spread of power outputs so I'll be going for this one.............
http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD (http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD)
Item AA0274
That's the one, Mick. I was getting back to you on that, but you've beaten me to it. Glad you found the site. Jaycar are a NSW-based company who have expanded dramatically since they started up. I'm lucky enough to have a local store where I live and can pop in and out whenever I want, and know the staff really well. It is truly an Alladin's cave full of all sorts of goodies (including helos and quadcopter drones, Scotsoft!), as well as electronic components of all kinds. You should have a look through their catalogue - it's very impressive. The British magazine "Everyday Electronics" publishes a lot of Australian designs and Jaycar advertise in it every month, so for all I know there may even be a branch or two over there in the UK.
Another neat thing about this LED tester is that it has two sets of 5 and 10mA outputs, which means you can compare the brightness of two LEDs on the same current. This means that you can match the brightness of two LEDs which may be side by side on a control panel, for instance, thus giving a professional appearance.
As for the Tour de France, Mick, I haven't seen it - Mrs Bealman (aka Anne) has had Wimbledon on. :worried:
Quote from: petercharlesfagg on July 06, 2015, 08:50:43 AM
I have ordered a a small tube of silicone sealant instead.
Well looks like my helpful comments weren't. Apologies.
Pity you are not within a 100km or so, could just nip over and sort it out.
The silicone rubber is a good solution. I am not particularly fond of hot glue guns. Mine tend to be like teething babies, dribble every where.
cfj
Jaycar is indeed an Alladin's cave and like Bealman, I am also lucky to have one not too far away.
I seem to remember that Peter mentioned something about buying the LEDs in bezels and dispensing with all this hot glue cold glue carry-on. Jaycar carries a piece of kit called the Mini Chrome Bezel which come complete with either a red or green 3 mm LED complete with current limiting resistor suitable for 12 V. To install simply drill a 5 mm hole in your panel, push through, and fix with the supplied backing nut. Cost may be an issue as they are $4 a pop - but will save a lot of grief and look terrific. I use them on my panel. No doubt there is something like this in the UK or maybe even in China at a fraction of the cost.
Tennis - arrgh! Just seems to go on for ever and ever with same old players going round and round and gets in the way of other sports.
Webbo
Quote from: Webbo on July 07, 2015, 07:59:27 AM
Tennis - arrgh! Just seems to go on for ever and ever with same old players going round and round and gets in the way of other sports.
Oh, I dunno ... that Heather lassie gave the Williams woman a hellova run for her money - I'd put money on her pulling through next time ! Shame she just couldn't finish in the last few games :-X
Quote from: NinOz on July 07, 2015, 07:28:10 AM
Quote from: petercharlesfagg on July 06, 2015, 08:50:43 AM
I have ordered a a small tube of silicone sealant instead.
Well looks like my helpful comments weren't. Apologies.
cfj
It appears you are misreading my comments, OF COURSE your comments were helpful, if they had not been so I would not have bothered replying. (Like tennis!)
We have differing views that is all!
Warmest regards, Peter.
Quote from: MikeDunn on July 07, 2015, 08:56:54 AM
Quote from: Webbo on July 07, 2015, 07:59:27 AM
Tennis - arrgh! Just seems to go on for ever and ever with same old players going round and round and gets in the way of other sports.
Oh, I dunno ... that Heather lassie gave the Williams woman a hellova run for her money - I'd put money on her pulling through next time ! Shame she just couldn't finish in the last few games :-X
I'm half to blame here, but let's get back on topic - LED failure! :thumbsup:
Thank you George.
.................................................................."..............................................................
FYI.
Our good friend, Malc has offered to visit my home and assist me with not only the LED issues but also with possibly helping me understand the basics with my Circuit tester!
I know from a previous visit by him that his knowledge will prove invaluable!
Regards, Peter
PS Watch this space!
That's great! Ex-NE guy as well. :thumbsup: :beers:
George
When Malc does pay you a visit Peter, it may prove worthwhile if you could video the session when he is showing you how to use your multimeter. That way you can watch the video over when you are unsure of some function :thumbsup:
@Malc (http://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=497) :NGaugersRule:
cheers John.
What, like that tutorial on YouTube where the bloke doing it blew the multimeter up and just about killed himself? ;D ;)
George
Quote from: petercharlesfagg on July 07, 2015, 09:37:05 AM
Thank you George.
.................................................................."..............................................................
FYI.
Our good friend, Malc has offered to visit my home and assist me with not only the LED issues but also with possibly helping me understand the basics with my Circuit tester!
I know from a previous visit by him that his knowledge will prove invaluable!
Regards, Peter
PS Watch this space!
That's very kind of Malc. Perhaps either you or Malc could post what the actual problem was for us poor confused people. Ta.. :thankyousign:
Quote from: newportnobby on July 06, 2015, 09:18:46 PM
Thanks John, but with Lawrence's help I reckon we've found the one George has, and it appears to have a better spread of power outputs so I'll be going for this one.............
http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD (http://www.jaycar.co.uk/productView.asp?ID=AA0274&w=led+tester&form=KEYWORD)
Item AA0274
Drat. Minimum order is £10 so I'd have to get 3 of these. Happy to do so if anyone else local to me in Leyland, Lancashire wants one or is prepared to meet postage costs?
They're only little and don't weigh much (especially without the battery) so postage shouldn't be much.
A great bit of kit definitely worth having if you are working with LEDs. :thumbsup: