Episode 19 Part 4 of JMRI via Bluetooth serial

[@markh4531]

Very interesting. Great content.

[@FunWithHOScaleStuff]

Thank you for the kind response.

[@mike9repeating]

Nice job, thanks for sharing. I understand your concerns with multiple power supplies. Hope all goes well.

[@FunWithHOScaleStuff]

Thanks for your kind comment. There are a number of issues but I think I haven't yet hit any roadblocks. I guess we'll see.

[@Christiane069]

When you said that the 78L05 has two power sides that seams to be independent (if I understood correctly), would that what they call Opto-isolation? Also, since this unit is for the (like me) electronic ignorant (OK I am not 100 percent ignorant), safe to use as it is? I also notice that your USB is USB-B both sides. Where do you get those anymore, are they needed to run this system?

[@FunWithHOScaleStuff]

Excellent questions. 1) To achieve optical isolation, a device must convert an electrical signal into light using an LED and then use a light sensitive detector to receive the light signal which in turn is converted back to an electrical signal. This assures that either side of the opto-isolator device electronics do not pass any of the electrical signal. There are ICs that are opto-isolator chips that can do this. (I use one in my DCC monitor circuit.) I may have misunderstood the L78L05 chip. It may actually be connecting the two ground signals together. I will have to check that with my ohm meter. Thank you so much for questioning the isolation issue. 2) About the cable, I bought it off of Amazon. It is a special cable. Most USB B 2.0 type male ending cables come with a USB A type female connector on the other end. I believe that the USB B 3.0 connectors are backward compatible with the 2.0 so it should be possible to use the newer version of the type B connectors. You're right, the type B is bulky and no longer used on new products.

[@Christiane069]

OK, thanks for all responses. Now, if the chip use a common voltage for both grounds, then how do you get two different voltages in one chip; builtin resistors and diodes? That's were I always get confused with electronic circuits. Love your site.

[@FunWithHOScaleStuff]

The actual circuit used in the LML05 voltage regulator is not published but the simple diagrams that are available for these chips only show it as a three terminal regulator. That would imply that the chip has a single ground reference for both the input voltage and the regulated secondary voltage. Thanks to your question I used my ohm meter and found that all four GND pins on the chip are a single electrical path having 0.1 ohm resistance. So the Arduino USB ground and the NCE Cab Bus ground are connected. I'm glad you raised this concern. I'll have to be careful with the separate power supplies. Thanks again for asking.

[@FunWithHOScaleStuff]

Perhaps I am misunderstanding your question. Let me offer the following explanation and I hope I am correctly responding to your question. When a different voltage is desired than one that is available it is sometimes possible to use a voltage regulator chip. The chip's input voltage must be greater than the voltage it creates on its output because the input supplies the energy for the conversion circuits. Integrated circuits are build using resistors, diodes (PN junctions) and transistors etched into the silicon of the chip. It would be reasonable to assume that the IC is using a kind of loss amplifier biased by a precision reference Zener diode. I'm speculating so the true answer to your question is that IC manufactures consider their actual circuits proprietary and don't usually publish them. I hope I understood your question. Cheers.

[@Christiane069]

Thanks for the answer. One more question: Since you stated that this chip is a regulator, then my basic question is why do you need this regulator between the Arduino and the NCE cab controller. If you were to use Digitrak would you need the same set up, or is it that the NCE you have is the build-in self contained controller and not just a basic cab unit. The all shebang puzzle me a bit.

[@Christiane069]

I forgot, the correction appears very short, maybe a bit longueur so we can read it. OK, I can stop the video. Just to say.

[@FunWithHOScaleStuff]

Hi. Thank you for raising that concern. I reviewed the video and I see exactly what you mean. I'll be more careful about how long I display a message on future videos. Thanks for taking the time to help me improve my videos.