stan2004 posted:stan2004 posted:...Yes, resistors in series add. Or, equal resistors in parallel divide by 2 - you may have 2 100k resistors which in parallel would make a 50k
From what I can see, it looks like this is what the NJ-HR group did. 2 100k resistors in parallel (50k) in lieu of a 51k.
That is correct. Radio Shack didn't have a 51K, so I used two 100Ks in parallel
Bob D
Was just reading the following thread about a train mount-able tiny video camera for only $21. I think the wireless ones are maybe $100 or so?
https://ogrforum.ogaugerr.com/t...y-layout-for-just-21
If the video electronics doesn't interfere with the signal-strength meter this might be a way to record the signal-strength readings on a route so you don't have to follow the train around. The video itself could be saved for later comparison or sharing via youtube or whatever to get opinions. If the camera captured both the changing meter display and the layout in the background perhaps additional eyes can uncover some correlation - maybe a small mirror if the meter lies flat on a flat-car. Of course there are smaller meters than the Harbor Freight freebie but then the "system" would cost more than 10 cents! 
I was actually thinking of using the GoPro to record the readings Stan. I'm just trying to figure out how to get it aimed at the display on the meter. My little test train would be up to 4 pieces: the LC+ engine, the meter gondola, the electronics/antenna car, and now the camera car. Talk about a work train.
You can get a 2.4ghz camera and receiver for less than $50. How about eBay 111774290029 for $18?
I was thinking some kind of mylar sheet (craft stores) or the like angled so the meter can lie flat on its back. The camera could then capture the meter reading (albeit upside down) and the moving layout in the background. If going thru a tunnel (if it's wide enough to handle the meter) you'll need a light since the Harbor Freight meter does not have a backlight for its LCD - but then again what do you expect for FREE? 
Upon reflection (!) Harbor Freight also has freebie LED mini-flashlights which you could mount. So since it appears you already have the video device the budget under a dollar! 
That's beautiful Stan. I actually have a small mirror that would be perfect for the task. I'll switch the gon for a flat.
Lighting is no problem. No dark tunnels on the layout yet.
Harbor Freight has a version of that same meter with lighting, but it isn't free.
Here we have the R2LC with the lead soldered to pin 13. Seems to be a good joint, not touching adjacent pins.
Here we have the donor chassis, a bay window caboose with a light. I folded the original light bracket down flat, and clipped the light to the body mounting bracket.
This is the resistor & capacitor part of the circuit. I didn't have a 51KΩ either, but I had a 47K and a couple 2200's, so 51,400 it is. The resistors are in series with each other and the capacitor is in parallel with them.
I scratched the black finish off a spot on the chassis and soldered on the ground wire.
I cut a block of wood to size, put in the antenna posts, then hot glued the block to the chassis. I also hot glued the two components to the wood block.
I added the ground leg to the resistor cap unit.
There are 3 white wires and one black one tied together here. The ground source soldered to the chassis, the lead from the resistor cap unit, a loose lead which will connect to the R2LC, and the black one is the lead to the meter.
I soldered on a piece of brass wire the correct size to fit the board socket. This black wire comes direct from the pickup rollers.
The white wires are all track ground.
This junction connects the pin 13 lead (black), the resistor cap combo and the other meter lead.
Because the pin diagrams are mirror image, I hope I got this right. I based the placement off the photo of NJ club's unit. The black and white pair are hot and ground. The orange is my antenna, and the odd black wire in the middle is supposed to be the light.
I have the meter set to 200μ DCA.
Any ideas where I went wrong?
Check for voltage on the MC3372 chip - Pin 4 = +5.7V, Pin 15 = Gnd
Thanks Dale, I'll run down and check that. Is that AC or DC? I'm guessing DC. Does it look like I have the power connection correct going into the board?
Pin 4 is a DC voltage.
I assume you added the caboose light so you could send TMCC to the engine to turn it on/off to confirm the R2LC is functional? It seems to me you should get the light functioning and then move on to troubleshooting the pin 13 meter output. In my opinion anyway...
Did you move the lead on the meter to the current hole? You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected. You should program the R2LC so you can control it and turn the light on/off as Stan suggests, then you know for sure the rig is working and receiving.
The current hole is only for the 10A DC range.
You might need to add a Program/Run switch if you want to exercise the light.
I got my meter car working this afternoon. I can see up to 60 uA as the maximum signal.
gunrunnerjohn posted:Did you move the lead on the meter to the current hole? You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected.
For the low current ranges, it's the same two "holes" as for voltage measurements. The upper "hole" is only for the 10 Amp DC current range which is not in play at this time.
Thanks Stan, not like any of my meters. I guess I'm not used to the HF special.
gunrunnerjohn posted:I guess I'm not used to the HF special.
But what's nice about the HF special is the battery test mode which puts a load (albeit a small one) on the battery...something you don't find on meters costing many times more than $0. 
I think I have one of those in my wood shop, maybe I have to dig it out.
gunrunnerjohn posted:Did you move the lead on the meter to the current hole? You didn't provide a shot of the whole meter, so I can't tell where you've got the leads connected. You should program the R2LC so you can control it and turn the light on/off as Stan suggests, then you know for sure the rig is working and receiving.
What's the input impedance of these meters? It seems y'all are developing a voltage across the 50K resistor and then shunting it with an ammeter. So...if the input impedance of the meter is 10 Meg or so (typically), you can use the voltmeter. Max reading from the data sheet is 60uA or 3 vdc across the 50K.
Anyway y'all had me confused.
And y'all are making me want to build one of these...
Dale Manquen posted:Check for voltage on the MC3372 chip - Pin 4 = +5.7V, Pin 15 = Gnd
Just did this test, 0 V. Makes me wonder if this board's no good.
I got it out of a bucket of stuff that Matt had been working on. Not sure if it came out of something or was supposed to go into something. If it came out, it could have had a problem. The only other thing I can think of is the brass pins I attached to the leads aren't making contact in the board socket, hence no juice.
If it came out of the box it might be bad from that Genesis I had to upgrade. Try a different board
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