Tuesday, 25 April 2023

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

Ian,

OK, now you have a working circuit but the choice of resistors is off, 550 will have the LEDs running at 23mA which is above the normal for LEDs, they will be like spotlights and prone to let the magic smoke out, especially the green. I would go with at least 1K, even up to 5K for the red (top) and bigger for the green to balance the colours. This will reduce your current draw and save your eyes. Modern LEDs are very efficient and bright.

I have uploaded photos to your album of a quick test circuit for power and colour comparisons. This is running on 11.87 volts. The top LED is using 620 ohm resistors middle 1K ohm and the bottom has 10k for green and 5K for red
Quiescent current for the top 9.57mA red lit 15.97mA green lit 14.69mA. This is a little lower that what you proposed and still glaring.
Quiescent current for the middle 5.93mA red lit 9.9mA green lit 9.2mA. This is the minimum that I would use and still very bright.
Quiescent current for the bottom .79mA red lit 2.02mA green lit .96mA. This is what I would recommend, Hook up one as a test before commiting just incase your LEDs are different.
Just for reference the total current for the board running red is 27.39mA and green 24.73mA

As you can see the LEDs are very bright even at low mA, You don't want to have to wear sunglasses to play trains.

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

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

Hi,

There is still a minor tweak to be made to the resistor values. I wanted to get the concept right first which has been done. As far as experimenting goes, I'll give you an example. On my concept board, I added another LED of the same type in parallel but reverse polarity The GREEN part of the LED suddenly decreased in brightness, not much difference in the RED brightness, then when I activated the limit switch to reverse colours the same thing happened with the other GREEN LED, so in this situation , the GREEN resistor has to be adjusted.

Yes, the GREEN LED (NC) is the default colour.

When the turnout moves, the throwbar acts with the limit switch to change the indication. Quite simple process. Hope that explanation makes sense.

Ian..

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Re: [electronics101] Photo Bi_coloured LED test Final concept.jpg uploaded

I noticed that the resistor values were identical. I also read in this thread that the values might best be chosen based upon the red LED's specs and that adjusting the value of the resistor for the green LED would allow balancing the relative brightness.

I wondered if you had experimented with the values or not? Also, is the Green LED the (nc) Default color?

How do you physically move the switch? Am I correct in assuming a momentary contact switch cycles the track from position A to position B?

It's been a while since I had my (Lionel) train set.

G.T.

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Monday, 24 April 2023

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

The following photos have been uploaded to the Connecting 2 pin bi-coloured LED to a NC/NO micro limit switch album of the electronics101@groups.io group.

Bi_coloured LED test Final concept.jpg

By: Ian Bell <genealogyinfo@bigpond.com>

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Sunday, 16 April 2023

Re: [Amateur-repairs] SSB Test Equipment?????

Also useful is an sdr not only to look on the if signals but also listen to that signal

Dg9bfc sigi

Am 15.04.2023 17:40 schrieb Dave Phillips <utahdog@msn.com>:

Robert

Distortion of SSB signals can be caused by many things, but it is important to understand the various frequency transitions that occur in the receiver IF through Mixing and Filtering. SSB requires the shift of the IF by 1.5 KHz to center the signal in the appropriate sideband, and any offset of one of the internal IF oscillators used can result in distortion.

When working on any HF radio, you need to examine signals in the frequency spectrum, and for this you can't beat the utility and accuracy of a decent Spectrum Analyzer. It does not have to be a high-priced Lab monster, the popular and readily available Tiny-SA will work very nicely.
--
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73's
Dave - KB7JS

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Saturday, 15 April 2023

Re: [Amateur-repairs] SSB Test Equipment?????

Robert

Distortion of SSB signals can be caused by many things, but it is important to understand the various frequency transitions that occur in the receiver IF through Mixing and Filtering. SSB requires the shift of the IF by 1.5 KHz to center the signal in the appropriate sideband, and any offset of one of the internal IF oscillators used can result in distortion.

When working on any HF radio, you need to examine signals in the frequency spectrum, and for this you can't beat the utility and accuracy of a decent Spectrum Analyzer. It does not have to be a high-priced Lab monster, the popular and readily available Tiny-SA will work very nicely.
--
________________
73's
Dave - KB7JS

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[Amateur-repairs] SSB Test Equipment?????

I am about to start again working on my Collins 51S-1 receiver with a SSB issue. Basically some distortion when receiving SSB signals, USB-LSB, but AM is fine..

I have used my Icom IC-705 as a test generator to transmit a signal but that is not that user friendly. Is there a way I can use test equipment to generate a SSB type test signal. Then I can troubleshoot things mush better..

I have recently upgraded my test bench with new state of the art equipment, but also some vintage equipment that can be helpful..

My only thought is I have a new RIGOL DG952 Function/Arbitrary Waveform Generator, 2 Channel, 50 MHz, that might be used in conjunction with my fully synthesized HP signal generator, but with SSB, there is no RF carrier present?

Any ideas would be appreciated..

Robert

WA6PHN

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Friday, 14 April 2023

[Amateur-repairs] SSB Test Equipment?????

I am about to start again working on my Collins 51S-1 receiver with a SSB issue. Basically some distortion when receiving SSB signals, USB-LSB, but AM is fine..

I have recently upgraded my test bench with new state of the art equipment, but also some vintage equipment that can be helpful..

My only thought is I have a new RIGOL DG952 Function/Arbitrary Waveform Generator, 2 Channel, 50 MHz, that might be used in conjunction with my fully synthesized HP signal generator, but with SSB, there is no RF carrier present?

Any ideas would be appreciated..

Robert

WA6PHN