Metalwork - Lathe and Mill topics: May 2023

Sunday, 21 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Ian,

Sorry for the delay, I was in Clare for the wine festival and only had very flaky internet.

You started well but there has been a small slip in either my describing or your reading. Either way it is easy to finish from here.
What you are doing is asking the LEDs to share the resistors which they don't do very well, I did mention this earlier and that is why the greens are not lighting up. The reds are using different ohm resistors which is why one is brighter.
What you need to do is go back to having a pair of resistors for each LED. I have altered the diagram to show this.

Follow the power from the +12V through the NC of the microswitch to the COM then to both LEDs. The top one will be green and the power will flow out through the resistor junction which will be at about 7.2V (60%12) then through the 1.5K (R2) to 0 V. The bottom one will be red and power will flow out through the resistor junction which will be at about 4.8V (40%12) then through the 1K (R4) to 0 V.

When the microswitch is activated +12V flows through R1 and R3 to the LEDs via their resistor junctions (7.2 and 4.8) The top one will be red the bottom one green, the power from both will flow out through the COM of the microswitch and NO to 0 V

(And yes, all those about to chastise me, I do know that the current actually flows the other way from negative to positive but it will only confuse the situation for the learners if we start on that)

Tony
https://ozfreemo.com
https://adelaidemodelrailroaders.com

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Saturday, 20 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi Tony.

After some delays due to other things happening here, I have finally been able to experiment with resistors. I replaced the 510Ω with 680Ω as the "base" resistor, then added and replaced 100Ω, 200Ω and 300Ω,and I finally got a "base" figure of 680 + 300 to give me 980Ω. I rounded that up to 1KΩ, and then reset from there, and finally settling on1.5KΩ for GREEN, and 1KΩ for RED.

I then setup a second LED, let's call it L2 and the first L1, and proceeded to check the operation, but this is where I have run into trouble. As you know when GREEN on L1 lights, so does RED on L2 since this is the default setting via the NC control on the limit switch. However when I do this the RED on L2 is brighter than the RED on L1, also the GREEN does not light at all on either in RED position, which to my mind indicates, that the resistors on GREEN are to high.

FWIW R1 is the 1.5KΩ resistor and R2 is the 1KΩ resistor. I have uploaded a modified incomplete copy of the original you specified earlier.

I won't add any more comment until I hear from you.

Ian.

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Tuesday, 16 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi Tony - and Donald,

Ok I will get onto it in an hour or so. Thank you both for your comments. When I saw Donald's comment I thought what do I now. Glad you were both on to it. I know the feeling, I've done a few things on my railway layout and thought later why did I over think that?

Until I've experimented a bit more, thanks again.

Ian.

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Ian,

Don't go shopping just yet. As Donald pointed out I am making this a bit complicated. I got carried away with trying to prevent the LEDs sharing one resistor and that I was using tectrode less LEDs that are way more sensitive and use less power. So let's get back to basics.

Build a test circuit like https://groups.io/g/electronics101/photo/286073/3614853?p=Created%2C%2C%2C20%2C2%2C0%2C0 but leave the resistors loose so that you can change them, connect them with your clip leads. then power it up. This does not need to be on a board, If you are happy with the red brightness then we will use that 510 ohm resistor this is the top one in that diagram. Then look at the green, if it is too bright then add more resistance to the bottom one in that diagram (put another 510 or whatever from your spares in series) play around with what is in your spares box, keep adding/adjusting until you have it the way you want it. Then add all those resistance values together to see what value you need and we will go from there.

Tony

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Donald,

Yes, you are right. I got a bit carried away with having the two LEDs and keeping them from sharing one resistor. I was also working with very sensitive tectrode less LEDs.
I will answer Ian and start him back at basics.

Tony

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

The multiple resistors and additional diodes don't make much sense to me. With the NO/NC leads available, one resistor in each leg would provide two different current levels for the two different directions without all the additional parts.

I don't see anything wrong with using the schematic of Original.jpg with R1 and R2 set to higher (and easily different) values to set the appropriate brightness.

Donald.

On 2023-05-15 23:15, miktrain wrote:

Ian,

Size of the diode make no difference, it is just more plastic.
Both resistors are used as they are feeding both LEDs one is red the other is green. Normally changing resistors will change the brightness but as there are two LEDs back to back then the red will change too. I have uploaded a solution for adjusting the brightness, Set your resistors on the board for red brightness with the diodes fitted, then adjust the new resistors for green to suit. These resistors and diodes could go on your board if you want, just make sure they are electrically wired the same.

This works by using your original resistors for both red and green but for green the new ones are added into the circuit. When red the diodes bypass (short out) the new resistors.
Increasing the new resistors will darken the green, increasing the original resistors will darken both red and green.

There are no silly questions, if you are stuck ask away that is what these forums are for.

Tony
http://ozfreemo.com
http://adelaidemodelrailroaders.com

Monday, 15 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

[Edited Message Follows]

Hi Tony,

Thanks for modified/updated circuit. I was just about to pay a visit to Jaycar anyhow, so I can get the extra parts. Do you suggest I should get the 110K & 10K resistors or play around with what I have in my resistor container. They range in value from 10Ω - 680Ω, and loose ones of 3.9K, 20K, 51K, 91K, 100k.

Do I still need resistors R1 - R8? Had to put off visit to Jaycar until tomorrow.

Thanks again for your help.

Ian

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi Tony,

Thanks for modified/updated circuit. I was just about to take a visit to Jaycar anyhow, so I can get the extra parts. Do you suggest I should get the 110K & 10K resistors or play around with what I have in my resistor container. They range in value from 10Ω - 680Ω, and loose ones of 3.9K, 20K, 51K, 91K, 100k.

Thanks again for your help.

Ian

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Ian,

Size of the diode make no difference, it is just more plastic.
Both resistors are used as they are feeding both LEDs one is red the other is green. Normally changing resistors will change the brightness but as there are two LEDs back to back then the red will change too. I have uploaded a solution for adjusting the brightness, Set your resistors on the board for red brightness with the diodes fitted, then adjust the new resistors for green to suit. These resistors and diodes could go on your board if you want, just make sure they are electrically wired the same.

This works by using your original resistors for both red and green but for green the new ones are added into the circuit. When red the diodes bypass (short out) the new resistors.
Increasing the new resistors will darken the green, increasing the original resistors will darken both red and green.

There are no silly questions, if you are stuck ask away that is what these forums are for.

Tony
http://ozfreemo.com
http://adelaidemodelrailroaders.com

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Sunday, 14 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Tony,

My circuitry uses your modified drawing of my Concept2 photo. (Concept2 mod). One thing I would like to mention is that the LEDs I'm using to test with are 5mm (Jaycar Part$ ZD0250 diffused), but the ones that will eventually be used are 3mm, (Jaycar Part# ZD0248 diffused). My mind is telling me that the size does not make any difference performance wise, it was just that I happened to have at the time 2 x 5mm size, and I now have a pack of the 3mm size.

Referring to your modified drawing, which resistors are used for GREEN and which are used for RED, I refer to them as the odd numbered and even numbered resistors. At 80 the brain cells are declining somewhat, so that is why all my questions. That is all my questions for this post. I hope this could be my post. (Maybe wishful thinking!)

Ian

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Ian,

This is why I said do a quick test before building. That is due to the red taking all the power and not enough left for the green, as I said LEDs don't share very well. I don't understand why only in one direction, double/triple check your wiring, is it what it should be?. Show me a quick diagram of what you have actually used. It is a bit hard to diagnose from your photos.

As I have said several times your resistors are way too small at 510 ohms and wasting too much power and not helping the situation. I have run LEDs on 12 volt at 110K for green and 10K for red but a little bit different wiring, that is 200 times higher and a correspondingly smaller current at micro amps. The ones in the photos I uploaded from the club layout are doing that.

Tony

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

That is exactly what you need to do. Increase the resistance in the one that is too bright.

Your design current (I think you are shooting for 20mA) is the current at which many of these devices is characterised. It is not necessarily any kind of "optimum", just a way for manufacturers to specify the characteristics so that it is easy to compare devices' voltage drop and brightness.

I'd be inclined to use less current all around, but I don't know your operating environment - you may need more or less light from the entire set. Also note that device-to-device differences can be visible when you get a lot of LEDs in an array.

HTH,
Donald.

On 2023-05-13 23:04, Ian Bell via groups.io wrote:

UPDATE:
Hi Tony, sorry to be a PIA, How can I set both LEDs to approximately the same intensity?

2 photos uploaded of test board and micro switch showing brightness of LEDs using 2 x 510Ω resistors. Should 1 of them be upgraded/downgraded to higher/lower value?

Ian

Saturday, 13 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

UPDATE:
Hi Tony, sorry to be a PIA, How can I set both LEDs to approximately the same intensity?

2 photos uploaded of test board and micro switch showing brightness of LEDs using 2 x 510Ω resistors. Should 1 of them be upgraded/downgraded to higher/lower value?

Ian

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Friday, 12 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi Tony,

I got my resistor values from an LED resistor calculator. I will add some screen shots for the RED & GREEN calculations for both 5% & 10%. The calculator shows both lowest and highest resistors for both colours.

Ian

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Ian,
Why are you stuck on 510 ohms? Build a quick test circuit, connect your resistor to the LED and power it with 12 volts, see how bright it is and if the resistor gets hot
I have recently fitted 2 colour 2 wire LEDs to the facia of the club layout and used 110K for the green and 10K for the red and they are very bright. I used a different method to wire them as we are running stall motors so just picked up the 12 volt from the switch that swaps the positive/negative for the motor and used a diode to bypass the 100K for red. I have uploaded photos for you.

Also unless you are only doing one or two, get your LEDs and resistors in bulk from Ali Express. For what you pay for a few of packs of resistors from a retailer you will get everything you need online I got 1000 LEDs for $29 delivered (less that 3 cents each) One of the members asked why I bought 1000 my answer was that the total cost was actually cheaper than 500 on ebay and faster delivery. I'm going to need lots for the 3 colour signalling that also I'm fitting to the layout, that circuit uses a 555 timer to flash the LEDs red/green at high speed so that it shows yellow for the third colour.

Tony
https://ozfreemo.com
https://adelaidemodelrailroaders.com

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Thursday, 11 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

[Edited Message Follows]
[Reason: Found typo.]

Hi Tony,

I'm revisiting your comment re resistors running hot. The resistors I have allocated are 0.5W, 510Ω, mini size metal film from Jaycar. Would I be better going with 1W, 560Ω carbon, as there is no 510Ω in that category. I'm in the process of wiring the PCB, and I think I have a couple of the 1W type to try out.

Ian

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

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Tuesday, 9 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

I think what you are calling a "schematic" is what I would identify as a "wiring diagram." The schematic is a symbolic representation of the circuit's functions; the wiring diagram tells a person where to connect the various wires to implement the schematic. There is no way I could have found the error you seem to have identified without substantial effort on my part to convert the wiring diagram to a schematic; so I didn't because I don't have that kind of time to spare.

Once you get the schematic correct, generating an accurate wiring diagram is a piece of cake.

Good luck,
Donald.

On 2023-05-09 19:15, Ian Bell via groups.io wrote:

I discovered a mistake in the schematic after I uploaded it. The wires to the limit switch were NOT altered in the tweaking of the wiring. I will attend to that later today. I can't do it now as I have a couple of medical appointments to attend to.

Ian

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

I discovered a mistake in the schematic after I uploaded it. The wires to the limit switch were NOT altered in the tweaking of the wiring. I will attend to that later today. I can't do it now as I have a couple of medical appointments to attend to.

Ian

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Monday, 8 May 2023

Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi Tony,

I have rearranged the schematic as you mentioned, and will place in the photo album.

Re your comment about the resistors running hot, and running the LEDs in series, I am considering it. Would you be able to indicate on my schematic the best way to this. My days as a sparky have long gone and I think I may have forgotten more than I learnt. (;

Ian

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Re: [Amateur-repairs] piece of mystery test gear id

Multi function test unit.

The 'oven' LED makes me think that one of it's uses is to test transistor performance at specific frequencies. Possibly to create matched pairs.

Nice unit.

Jim G4EQX

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Re: [Amateur-repairs] piece of mystery test gear id

To me, it looks ham home brew. Nicely built!

Multi-function bench tester.. maybe.

Signal tracer

Frequency counter

Crystal tester

Power supply

Volt meter

Transistor tester

Maybe more... or less, hi hi.

73,

Gary

WB6OGD

On 05/08/2023 12:45 AM Paul M3VUV <nanovnauser@gmail.com> wrote:

--thats what i thought but why the speaker and frequency readout?,it looks ex mil by the way its made,as in all wireing tied up etc,nicely made,seems too nice to break for bits.73
M3VUV

Sunday, 7 May 2023

Re: [Amateur-repairs] piece of mystery test gear id

a pic of the insides.

--
M3VUV

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Basically you have it right.
LEDs don't share very well and a 500 ohm resistor will probably get quite hot. You could get around this by running the LEDs in series so the power goes through the resistor then through one LED then the other (facing the opposite way). This would also save you four connection blocks. Test it before building.

One board would be fine but to make it easier and clearer to understand and work with if you cut your schematic in half vertically and swap the sides. This will mean the power lines would be down the centre and the outputs on the outside. Then there would be less crossover of tracks and wires.
So looking at the board it would be power in the middle, resistor network then outputs at each edge.

Tony
https://ozfreemo.com
https://adelaidemodelrailroaders.com

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Re: [Amateur-repairs] piece of mystery test gear id

Transistor tester? That's the best I can come up with from those pictures.

Re: [Amateur-repairs] piece of mystery test gear id

I cannot read all of the control markings, but, from what I can read and what I see, it looks like some sort of transistor tester. Could be for grading or sorting transistors?

It does look interesting.

73
Glenn
WB4UIV

On 5/7/2023 7:59 AM, Paul Larner M3VUV wrote:

Hi all,i got this bit of test gear today from a radio rally in lincs(dambusters rally) uk,it was just £2 so brought it,heres some pics,has anyone any idea what it is,it has no date or maker markings but has an xtal oven+ led readout etc,any idea what it is?,thanks m3vuv

--   -----------------------------------------------------------------------  Glenn Little                ARRL Technical Specialist   QCWA  LM 28417  Amateur Callsign:  WB4UIV            wb4uiv@arrl.net    AMSAT LM 2178  QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR  "It is not the class of license that the Amateur holds but the class  of the Amateur that holds the license"

[Amateur-repairs] piece of mystery test gear id

Hi all,i got this bit of test gear today from a radio rally in lincs(dambusters rally) uk,it was just £2 so brought it,heres some pics,has anyone any idea what it is,it has no date or maker markings but has an xtal oven+ led readout etc,any idea what it is?,thanks m3vuv

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

[Edited Message Follows]

Hi there,

Sorry I didn't reply sooner, but I have been tweaking the final concept. I have just added 3 more photos of my schematic. The "Final concept" schematic should be read in conjunction with the other 2 schematics attached in the photo album.

As I have 4 turnouts in conjunction with these schematics, I am intending to put the wiring for all 4 on one PC board. The final wiring is on the "Final concept" schematic. I would appreciate it if you think I would be better off doing 4 single PCBs instead of the one PCB, and if the wiring of all 4 is correct by adding just one 12V DC supply to all 4 circuits. There are 2 bi-coloured LEDs attached to each turnout, 1 bi-colour shows GREEN (default) the other should show RED, then when the original shows RED instead of GREEN, it's "mate" should show the opposite colour I I hope that all makes sense.

Re the brightness of the LEDs, as each resistor will be controlling 2 LEDs, for now that doesn't concern me to much.

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded #photo-notice

Hi there,

Sorry I didn't reply sooner, but I have been tweaking the final concept. I have just added 3 more photos of my schematic. The "Final concept" schematic should be read in conjunction with the other 2 schematics attached in the photo album.

As I have 4 turnouts in conjunction with these schematics, I am intending to put the wiring for all 4 on one PC board. The final wiring is on the "Final concept" schematic. I would appreciate it if you think I would be better off doing 4 single PCBs instead of the one PCB, and if the wiring of all 4 is correct by adding just one 12V DC supply to all 4 circuits. There are 2 bi-coloured LEDs attached to each turnout, 1 bi-colour shows GREEN (default) the other should show RED, then when the original shows RED instead of GREEN, it's "mate" should show the opposite colour I I hope that all makes sense.

Re the brightness of the LEDs, as each resistor will be controlling 2 LEDs, for now that doesn't concern me to much.

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