PS2 Lighting Question

The incandescent bulbs are all 6V bulbs.  Any LED class lights/markers will require series resistors/diodes as they don't have any current limiting, I'd suggest a 1k 1/4w resistor.  I'd just bolt the LM7805 (5V regulator) to the chassis, that will give you proper heatsinking.  The 12V regulator is too much voltage for the bulbs.

John,

Thank you for the reply.  Should I put a capacitor across the DC output of the bridge rectifier for better smoothing?

Earl

In order to use the rectifier, you'll need a filter cap, the regulator doesn't like to see pulsating DC.  I'd use a 470uf 35V capacitor.

John,

Does a full wave rectifier pulse?

Thanks,

Alan

Yep, just at a higher frequency.

I made the mistake at looking at the bridge rectifier output on a scope.  It wasn't as pretty as your diagram and it got even messier when I hooked the rectifier up to the train motor. 

The output of the voltage regulator looked like a half wave rectifier output.  The width of the 5 volt pulses just got wider when I cranked up the voltage on the input transformer.  I was expecting to see a straight line at 5v from the regulator.

My input transformer was a CW-80 which probably skewed the results.

Earl

You'll probably need a small resistor in front of the capacitor to isolate it from the motor draw, try a 22 ohm to start.  If you have an old smoke resistor around, that would work.

As for the ugly waveforms, you're just seeing the artifact of no load or the uneven load of the motor. The 'scope will display strange stuff with no load as there's very high impedance and coupling of the stray AC distorts things.

Here's my test, input AC signal from transformer, no load output, and output with a 330 ohm resistor.

I saw a scope kit the other day for about $18. Had a color TFT screen. Think this would be a waste of money or something worthwhile to play with? I should add, I have no idea how to operate one of these things. It would be a learning experience. DSO138 2.4" TFT Handheld Pocket-size Digital Oscilloscope Kit

The link you point to is a kit.  Seems to me I've recently seen an ad for a similar item all built up.    Digikey???? I agree, it's interesting at the price.

Yes, it is a kit, but pretty cheap. These scope pictures around here keep stirring my interest. I saw one somewhere that somehow connected to a PC for the screen and it seemed reasonable at the time as well, maybe $50-$60 or so, but I can't remember where I saw it? If you find the one you saw, please post a link.

However, if any smoke release is required as part of the 'learning experience' I'd much rather release it from the kit $18 than from the PC.  

http://www.jameco.com/webapp/w...001_10001_2205940_-1

http://www.digikey.com/product...109990026-ND/5488240

If it were my money, I'd go a little more and look for something more capable.

For instance, eBay 301802695998 for $150 shipped.  It's used, but it'll run rings around anything presented here.  This is just one of a ton of options.  I'd certainly want something that was a bit less limited than the 'scope kit.  IMO, that's just slightly above a toy.  Obviously, if you don't really need a 'scope, it might be all you want.  I see 20mhz capable USB models that interface to a PC or laptop in the $50-60 range, that would be the very low end of what I'd recommend.

John,

The train max speed seems to be reduced to about 1/3 of it's original speed.  I suspect the chassis ground on the voltage regulator may be the problem.  Should I have used an insulating washer to insulate the voltage regulator from the mounting screw?

Additionally the motor was pretty hot after about 30 minutes of running.  I would not have noted the hot motor, except that I removed the shell to add the capacitor.  So maybe the hot motor is normal. 

Here is the parts list:

Capacitor: 470uf, 35v electrolytic

Voltage Regulator 5 VDC, 1 amp Radio Shack P/N 276-1770

Full Wave Bridge Rectifier 50 volts, 4 amps Radio Shack P/N 276-1146

Here is what I have installed:

Thank you for your help...

Earl

Yes, you need insulation since you're feeding this from a bridge rectifier, I overlooked that.    You need the insulating washer and the insulating mica under the regulator.  The tab is ground, which is shorting out part of the bridge.

I added the insulating washer.  The mica was already in place from one of the DCS components (3.3v regulator).  I checked for continuity between the regulator and the screw and it is open.  The engine now runs at a more normal speed, although I don't think it is still as fast as it ran with DCS.  It will not derail at full speed on 042 curves using a KW at full power but the speed is close to derailment.  Regardless, the speed is fine for me.

BTW, I use an Owon 7102V digital scope and it works fine for a novice hobbyist like myself.

Thanks for your help...

Earl

I will have to check out your Owon scope, thanks for the tip. You obviously know how to hook it up at least, not sure I am that far along yet so I am below novice level. I will also check the links RJR posted. The one GRJ posted looks very nice, but I will probably start with something with a few less knobs.  I bet that thing contains a lot of smoke too, and probably needs it all to operate properly.  

I have seen ones like GRJ mentioned in the $50-$60 range that connect to a PC, that is what got me wondering about them. Then these screen shots keep appearing...  The $18 kit version was appealing because of price and my lack of knowledge, but I can solder up a kit. What to do with it (and how to do it) after assembly is the question...

Earl, your digital 'scope is very similar to the one I have, and certainly sufficient for anything you're likely to encounter.  You are obviously not the guy I was targeting with my 'scope purchasing advice since you have a nice one already.

RTR12, as far as posting graphics, my 'scope writes the screen shots to a USB stick, makes it much easier to post them.   If you want a decent model, something with the capabilities of the one Earl and I have start around $250.  For that you get 100mhz bandwidth, 1ghz sampling, and the ability to write the output to FLASH, as well as a serial or USB connection for computer control of the instrument.

I looked at the Owon, even found a couple of videos on it. It's a bit more expensive that I was wanting to spend, but it looked like a really nice scope unit. Lots of neat features. I have one more video on it to watch today. Maybe I need to read a book about all this before I get to far in to it. Or would that be to get farther in to it? I honestly don't know anything about these things, other than they do neat stuff.

GRJ, which one do you have? I will look for more videos.

Take a look at the models on eBay, you can get pretty nice stuff for under $300.  It's interesting that the prices have ticked up since I bought my ATTEN, but they're still pretty inexpensive.  I can remember when a 100mhz digital storage 'scope was around $7-8K to start!

I will look around on ebay, but with my luck if I get one there it probably won't work right and by the time I figure it out it will be too late to return it.  

They are still out there for those prices, but maybe a lot fancier now? While poking around last night I saw some used ones for some very impressive (think HIGH) prices!!! Didn't bother to note what they were, but they certainly were expensive! Now if I could find one that also toasted my morning bagel...

If they toast the bagel, they only do it once, then they don't work for their intended function after that.

So much for the bagels, I guess there's a drawback to every plan...  

I was also going to add coffee brewing, but I'll just stick with the toaster and coffee pot.