DCC Track Tester, make your own cheap track tester, for your model railway, Ep10
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- Опубликовано: 27 сен 2024
- In this video we show you how to make a really simple DCC track power tester for your DCC controlled model railway. It costs less than 50 pence to make. A DCC track power tester is a really useful tool for any DCC model railway layout to test or diagnose track power problems.
Please note, this will not work on DC layout
DISCLAIMER
Please note, this DCC track tester works for me on my n gauge DCC railway layout. I am not an expert and I can not make any guarantee that this will work on your DCC model railway layout.
This track power tester will NOT work on a DC model railway
should put a diode either inline or across the LED - LEDs don't like working as common-or-garden diodes and need protecting. A tiddly 1N4148 or 1N4001 will do the job
I was about to comment this. A diode is definitely a must have for DCC track. It could burn out the led if you don't use a diode.
You could also parallel another LED across it (reversed) . The forward voltage drop of one LED keeps the max reverse voltage below spec.
I like that it simulates a train and can show weak spots over points etc, someone will manufacture this for sure.
Thanks for the comment. Yeah I wanted something to run over point to check the switch blade contacts.
What a great idea, I'm on board with this, I have a couple of wheel sets that are in my parts box, and I'm going to give this a go. One suggestion if you clen the part your soldering too that might help. But using a little flux would do the trick better.. Anyway Thanks for a Great Idea !!
You should have a bridge rectifier in the circuit, or the LED won't last.
Or wire two LEDs in so called antiparallel. So one ligths up when the other one ist in reverse.
You need to add either a diode in series, or another led in parallel with the first but reversed. This is because leds will break with a reverse voltage of more than about 5v.
Thank you
Hi Thanks for the comment, of course this is true for DC, but I have found it actually works ok with the frequency of DCC.
@LlanfordParkModelRailway reverse bias will kill leds. Its more a problem with dcc, which as you say has a modified ac signal.
@@LlanfordParkModelRailway Yes, this actually works for a while, depending on the LED properties. However, damage is cumulative over time. There is more going on in the reverse condition than simple thermal damage that would be more quickly evident. In this use, the LED reverse maximum is exceeded by quite a lot, and then the resistor limits the current from being immediately destructive. Methods others have mentioned to cure this are proper and necessary.
You are so lucky that modern LEDs don't (always) fail on 12V reverse polarity. It is actually worth putting another LED in parallel, but the other polarity, so neither LED gets the full 12V. Or use a red/green two-lead LED, that has two in opposite polarities already.
Some uninformed people would say "Ah, well, it's got a resistor in series, so that's OK". No, the resistor won't drop any voltage until a current flows through it, and a reverse-biased LED should pass no current, so no voltage drop, so 12V straight across your LED, reverse-biased, and your LED is rated at, usually, 6V reverse, maximum. If you used a 1980s LED instead, it would just glow very brightly. And briefly.
Trust me, I've been an electronics engineer since 1975.
The Blutak was a good idea, though.
Excellent video presentation. Very interesting. Thanks for sharing.
Thanks for your comments
Simple brilliant off to make one now 😊
Top tip making one for checking frog polarity as we speak
Remember this will only work for DCC not DC
Yes I got that
I have found that a simple globe of 10Watts is better. The diode only draws a small current so wont pick up any high resistance problems. also as noted by someone else below LED requires a bridge rectifier, although a second diode in parallel will help to show direction on DC or both light on DCC. suggested globe is festoon type
Very cool
Nifty for sure 😊
Thank you for that, and it was so refreshing to hear soLder and not soDDer.
That's funny because the truth is that "sodder" is actually a more correct pronounciation. This is because the word "solder" originates from the French word "souder" meaning to fasten together.
Too simple for dcc power tester. Power tester, yes, but does the same with DC ( minus the very fast blinking, which can't be observed anyway ). As someone said, put a reverse LED, antiparallel with the existing one. When both lights up, at least it's detecting AC waveform, which can be DCC. If only one LED, it's DC.
Antiparallel? Is this the same as in series? Thanks
@@GRUMP5B nope, it' parallel, but reverse direction. LED1 anode to LED2 cathode, and lLED1 cathode to LED2 anode. Preferably different colored LEDs.
Thank you for the clarification, hopefully those who are not savvy in electronics will know what to do.
Do not forget that many LEDs ( especially the red ones) accept maximum of 5-6 V in reverse polarity, that means your simple detector can be easily demaged because, especially on DCC track, the peak to peak voltage is far above those 5-6 Volts. ( the resistor in this case has no influence because there is no current in reverse polarity).
I may be wrong but the track is the same voltage regardless of any inputs from the controller. The voltage is ac. The direction is a digital signal only to the decoder.
@@ocdaddvids This is exactly the problem. In DCC is an AC voltage peak to peak over 20 V in many cases over 30V. You see the light from the LED in the half periode when the positive voltage of the DCC is on the anode side. When it is on cathode side the LED will not lit but the voltage on the LED will be in wrong direction about 30 V and this is out of specifications of the LEDs.
The easiest way to add a second LED parallel to the first one just in oposite direction ( ie A to C and C-A) . In this case one LED will protect the another one. ( in DC you will get even an indication which rail is positive).
Made one of these with two track testers attached to a OO scale bogie,as each track tester is connected to one set of wheels it detects any brakes across joins in the track and as in DCC mode if the track is wired correctly. To use you connect it in front of a loco and drive it around....
Cool idea , going to subscribe your channel hello from Canada
Welcome aboard!
Brilliant idea! Thanks for sharing!