I think your onto something there Chuck! Id buy one.

Nice.  It looks much neater made than my voltage car.

AC voltmeters on both sides, counter on just the one side. That way you can see the voltage from both sides of the layout/loop or whatever. The counter of course just needs to end up where you started. Reset button on the side of the counter. I would like it on a big box car, but the new (I bought it a while ago) Williams caboose that came with all the windows falling out had just the right frame/rollers etc. to try it. The meters need their own supply, so I am using a 9 volt battery which lasts for shelf life...as little use as it gets.

I have one with voltmeters on both sides, but I don't have an odometer, pretty slick.

Thanks. I started with DC meters and a peak reading ckt, calibrated for rms (sort of). But the dang shark's tooth waveform was a bother. So I bought AC meters (cost a little more and required a separate supply) and did it over. The counter came later...I ordered a second different one of those also to get the one that did the job easily.

When you finalize the design, would you post a "how-to" please?

Slick.  Are you going to sell some on the Buy/Sell forum to help finance your habit?

What meters did you use.  I'm still screwing around with the DC meters, and accurate readings are problematic.

Yes...I did too and then ordered these. As I said, it was mostly to just use the measured voltage as the meter power. But too inaccurate so I ordered these AC meters which take an extra supply...but they are very low drain on a 9 vdc battery.

3 1/2 LCD Blue Digital VOLT Voltage Panel Meter AC 50V

http://www.ebay.com/itm/3-1-2-LCD-Blue-Digital-VOLT-Voltage-Panel-Meter-AC-50V-/110694181369?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item19c5e329f9

The best counter I found, easy to use, comes with wires etc. is this one...also runs on the same 9 vdc battery...also comes with a hook up wiring diagram...

4 Digit Red LED Counter Panel Meter DC 6-15V Up and Down Totalizer

http://www.ebay.com/itm/4-Digit-Red-LED-Counter-Panel-Meter-DC-6-15V-Up-and-Down-Totalizer-/250938320351?pt=LH_DefaultDomain_0&hash=item3a6d16e5df

There is really no design to it, just use a car frame with roller pickups on both trucks (like a caboose). I just used some 3M high strength automotive moulding tape which never dries out, come off clean (but sticks forever until you pry it loose). The tape is along the bottom edge of the meters and stuck down on the caboose frame. Then I just stuck a 9 volt battery with a snap connector that I just snapped one side on and swivel over to make like a switch. It would be nice to put it all in a big box car, now that I know what I want on it.

I try never to come out ahead on electronics, ham radio, trains, and motorcycles. So far, I am 100% successful.

Good work, Chuck –

Just wondering - - -

Is the magnet mounted on the axle of a wheel with a diameter of about 0.7 inches? This would result in a revolution every 2.2 inches, or about 5.4 revs per foot, and 54 revs or counts per 10 feet.

Thanks for sharing.

Alex

Yes that's it. I, however, just measured out 10 feet amd noted the counts. The reed relay is covered with heatshrink and superglued just above the axle, to the inside of the truck frame. The neomydium 5mm x 1.5mm magnet is stuck to the axle touching the wheel, also a drop of superglue...but it seems like it would stay there anyway. The counter either has a debounce ckt or the reed relay does not bounce, because the counts are clean and singularly occurring.

I'd be tempted to put a divider circuit in there to rack up scale miles, that would be cool!   110 feet is a scale mile at 1:48, so maybe have the counter measure in 10ths.   Have it count every 11 feet as you run.

Chuck,

I bet it has a built-in debouncer.The only sensors (of this type) I have seen that have clean pulses are hall effect sensors, which of course are not 'mechanical'.

What John suggested would be cool indeed!

Alex

A divide by any number up to 255 can be accomplished with an 8 bit comparator and an 8 bit resettable counter.  In our example of .7" per count and 11 feet for a scale mile, that number is 188.

I think a CD40103B might be a one chip solution, a pre-settable binary count-down.

John,

The .7 inches is the wheel diameter, and each count occurs approximately every 2.2 inches. And I believe it is 110 feet per scale mile (110 x 48 = 5280). And I know that you know this .

Alex

Right, faulty understanding when I read the thing.  However, my technique remains unchanged, just the number of counts necessary to do the job changes.   That's what I get for doing the math in my head and not with a calculator, slipped a digit.

110 * 12 / 2.199 = 600.27

I'd probably have the counter divide by 60 which would give me 10th of a mile on the display.

Actually the number is 594 counts per scale mile. 54cts/10ft x 11ft/0.1smiles = 594 cts/smile. The diameter of the wheel is not what I measured, what I did is that there are 54 cts per measured 10 ft of track. Of course, i would rather measure off 100 feet and more accuracy. So 600 is close enough. Maybe I'll count the Fastrack and go around a few times...but then that is why i did this...so I wouldn't have to count the track...heh.

Well, whatever the count actually ends up being, the same technique applies.  I'm sure you could get pretty close, and you have to remember fast angle wheels rotate faster/slower on curves as well.