I want to upgrade the lights in my athearn rtr sd40-2 to leds because the bulbs are way too dim, but the lighting outputs on the decoder seem to be 1.5v and the leds I have only work on 3v.
The decoder is some really obscure tsunami OEM decoder that I can't find the model number for, and the locomotive model is ATH98801. How do I get the normal 12v from this decoder?
Building my first layout, 4x8 contemporary urban area in HO scale
You can run a jumper wire from the right rail and hook has many LED's has you need. Each LED needs a resistor (1K) for starters. I said has many has you need - I would keep it at 6 or below.
is this a factory installed decoder? Was wondering how it is running if it does-- there is no wire hooked the the decoders motor + output?
Have you tried looking at the LED brightness on a AA battery? Most LEDs are rated 3 volt max but will actually light full brightness on as little as 1 volt.
Pete.
You might try contacting Soundtraxx (call or email) and see if they have any recommendations. If the lighting outputs on the decoder are only 1.5V then you may be stuck. However, there may be unmarked outputs that will allow you to add a 3V LED with a 1K resistor.
Tom
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"Types of Light Emitting Diode,Most common LED’s require a forward operating voltage of between approximately 1.2 to 3.6 volts with a forward current rating of about 10 to 30 mA, with 12 to 20 mA being the most common range."
This is what I got from an online publication about electronic components. It is because of the low operating voltage that some decoders are incapable of dimming them. The decoders capable of dimming an LED limits the current instead of the voltage. When programming such decoders there is a setting in the lights for LED.
woodone Was wondering how it is running if it does-- there is no wire hooked the the decoders motor + output?
It looks liek there is a metal strip on the bottom of the decoder for the motor + connection.
Traincraft199How do I get the normal 12v from this decoder?
You would have to find the positive output from the diode bridge rectifier circuit (I think I know where it is from the pictures, but I'm not "positive" ), but it's not really necessary. Like woodone said, you can use one of the rails (can actually be either one) as the + common. It would actually be about half your track voltage, because it's "half wave" power.
Maybe this will help. In order to install LEDs or bulbs with the TSU-GN1000 you will need to wire to the +14 common. To locate the +14 common look near the two silver capacitors. You will see a small brass circle that goes all the way through the board and is labeled +14 in white letters. This will take place of the existing common (+). For LEDs you will need to wire in a resistor for each light"
wrench567 Have you tried looking at the LED brightness on a AA battery? Most LEDs are rated 3 volt max but will actually light full brightness on as little as 1 volt. Pete.
Yeah, it actually works great with 2 AA batteries but does nothing on a single battery.
ba&prr Maybe this will help. In order to install LEDs or bulbs with the TSU-GN1000 you will need to wire to the +14 common. To locate the +14 common look near the two silver capacitors. You will see a small brass circle that goes all the way through the board and is labeled +14 in white letters. This will take place of the existing common (+). For LEDs you will need to wire in a resistor for each light"
I did find this in some of my research, yet I was unable to locate it on my decoder. I don't think my decoder has one, or maybe it's unmarked as tstage said.
CSX Robert You would have to find the positive output from the diode bridge rectifier circuit (I think I know where it is from the pictures, but I'm not "positive" ), but it's not really necessary. Like woodone said, you can use one of the rails (can actually be either one) as the + common. It would actually be about half your track voltage, because it's "half wave" power.
I think I might try this. The only thing that confuses me is that when I probe a lighting function with one of the track terminals, the multimeter about 6 volts no matter if the light is switched on or off. (maybe I'm missing something? I'm not an expert)
Look at the 8 minute mark on this guys video.
Install a Soundtraxx Tsunami, GN-1000 in an HO Scale Athearn GP38-2 - YouTube
I have no idea who he is.
Lee
Lee 1234 Look at the 8 minute mark on this guys video. Install a Soundtraxx Tsunami, GN-1000 in an HO Scale Athearn GP38-2 - YouTube I have no idea who he is.
My decoder doesn't have the marked 14v hole he's talking about
Traincraft199The only thing that confuses me is that when I probe a lighting function with one of the track terminals, the multimeter about 6 volts no matter if the light is switched on or off.
Interesting, it sounds like something in the circuit pulls the output to ground even when it is off. It would be a very weak pull-down and not able to source any appreciable amount of current.
I took a closer look at the decoder. In the bottom picture, there are four large doides on the right hand side - those are the bridge rectifier circuit. It looks like the left side of the two inner diodes are common and are the cathode end of those diodes, so that would be the + output of the bridge, so you shold be able to connect to either of those solder points to pick up approximately +12V, depending on what your track power is.
CSX Robert Interesting, it sounds like something in the circuit pulls the output to ground even when it is off. It would be a very weak pull-down and not able to source any appreciable amount of current. I took a closer look at the decoder. In the bottom picture, there are four large doides on the right hand side - those are the bridge rectifier circuit. It looks like the left side of the two inner diodes are common and are the cathode end of those diodes, so that would be the + output of the bridge, so you shold be able to connect to either of those solder points to pick up approximately +12V, depending on what your track power is.
I think you're right. I probed it with a multimeter and showed 12v when the light was on. And it lights the led with a 1k resistor! I'll try wiring the leds to this.
Look at the 8 minute mark on this guys video. Install a Soundtraxx Tsunami, GN-1000 in an HO Scale Athearn GP38-2 - YouTube I have no idea who he is.
Interesting....
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You cannot. On some Athearn decoders the FX output voltage depends on the common (+) bus and if you switch from +1.5 V bulb bus to +12 V bus, you'll be able to convert to LEDs.