I'm interested

I am interested. Keep the post coming.

Microswitch

Is the microswitch needed? I would think the DCC servopoint board would take care of that?

Found a PDF explaing why the microswitch is needed

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEEQFjAA&url=http%3A%2F%2Fdivision15nmra.com%2Fuploads%2FTurnout_Motors_from_Servos.pdf&ei=nmgTUoOSEKm4yQG7s4DIAw&usg=AFQjCNGfW78KHpyu6mYS8JCOjeUc_5Gw8w&sig2=Svr2r5WQHEAipS8fJ1eqxQ&bvm=bv.50952593,d.aWc&cad=rja

Bravo

Nice work there Old Goat. For a first time electronics project I'd say you did very well. Nice board layout and good soldering. You learned well.

Now about those 2-36 screws. You did say you had piggy fingers, right? So you must have meant 2-56, right? or is there such a screw size in Africa we don't know about? Inquiring minds you know.  

Bernd

P.S. just so I wouldn't have egg on my face I looked in my "Machinery's Handbook" to see if their was such a critter. I didn't find any.

2-56 Screws

Hi Bernd,

Yes, Piggy-fingered indeed. Should have typed 2-56 - my error.

When SA metricated back in 1969 we went the whole hog and dropped all the imperial stuff. We were not ever allowed to by inch rulers!

Cheers,

Neville

Resources please

Hello,

I googled the Joseph Norris article you referenced, but didn't come up with it, do you have a link to it?

Also can you provide the link to the ATX PSU to a DC bench top power supply you used? Since there are so many figured I'd follow the one you used since I know it works!

As for Rob's link not sure why it is so complicated for the PDF article he mentioned, so here it is a little more readable, not that his doesn't work:   http://division15nmra.com/uploads/Turnout_Motors_from_Servos.pdf

2-56 screws vs. metric

Well I found this little table that may help you find the metric "equivalent" of a any U.S. (really SAE) screw.  The 2-56 designator is size (#2) -  threads per inch (56). A metric screw is diameter x thread pitch (distance between threads) a M2 x .4 is 2 mm diameter and then .4 mm thread pitch.

So for a 2-56 a metric screw M2 or M2.5 would be fine, the actual size of a #2 is 2.1 mm, the thread pitch doesn't really matter,  as you will be buying the nuts at the same time to match the thread pitch of the bolt.

Just for completeness 56 threads per inch is roughly .45mm thread pitch.

http://www.votawtool.com/product_help/Thread_Sizes.asp

Other uses...

I'm thinking that if you eliminate the electronic controls, you could remove any physical stops present at the same time - giving you a high torque slow motor that could be used to drive a turntable or transfer table. Looks like I'm going to have to do some experimenting...

Other uses

barr_ceo

Now your thinking. I've seen articles were they remove the potentiometer so you can get continuous rotation. Then all you need is to get the proper supply voltage, which I believe is some were around 4.5 or so volts. Here's a place to start your research at. http://www.servocity.com/

Good luck and have fun.

Bernd

Micro-Servos

Oh, I fly RC planes, too, mostly ultra-micros. There's a full service RC shop just down the road. I'm not going to cannibalize one off one of my planes for this, though.

Speaking of servos.... have you seen the REALLY small ones on the Ultra Micro planes?

I have some ideas on using these on board N scale cars with some Zimo decoders... 

Ultra Micro Servos

Being interested in animation for model railroading I've played outside the model railroad sandbox and looked at what the model airplane, car, helicopter and robot guys have. Lot's of goodies that can be applied to animate model railroad stuff. Have you seen this servo? Uses a bio wire for control.

http://www.hobbyking.com/hobbyking/store/__6405__toki_biowire_1g_micro_servo_world_first_.html

Bernd

For something more conventional...

Was talking about these in another thread...

((Pic deleted... no reason to post it twice...))

Linear action Micro Servo, as used in Ultra-Micro aircraft. This one is on my F4 Corsair.

EtA: Laughing... OK, it was on another PAGE in THIS thread...  < < sigh

Part Number

Do you have a part number for that servo??

Quad Pic

Part number

Did a little searching. Can't find a number from the manufacturer. Hobbyking has it lasted as "TK-RC1".

These servo's can be found and bought from any of the shops that supply the airplane, R/C car, R/C boat, R/C helicopter and Robotics enthusiasts.

Bernd

DYI

I think Neville (Old Goat?) is a DYIer and would probably prefer not to spend the the dollars on such an item. Plus I believe it would be quite costly to import to his country.

Bernd

Here's one listing for the

Here's one listing for the Ultra-Micro servo

http://www.horizonhobby.com/products/1-9-gram-linear-long-throw-bb-servo-SPMAS2000LBB

The local hobby shop here carries them, as well.

Why mangle a servo

I applaud you effort; however, why mangle a servo - even for cost - when with a few more components you can build a circuit which will drive any standard servo without disassembly. There were several circuits using NE555's published about a decade ago. Add a double throw relay and a couple more components and you have power switching for the points. I have been searching for links to the schematics, but have not found them yet. Newer designs for driving one servo can be built with an eight pin microprocessor using as few as eleven components, or one for driving four servos can be built with a fourteen pin microprocessor using as few as fifteen components.

Yes the microprocessors do need to be programmed, but the code is available on the web. An example of a circuit schematic for driving four servos can be found on the MERG website ( Using servos).  

I applaud you effort;

I think you just answered your own question... 

Some folks aren't even comfortable soldering rail feeders. Something like the above is simply out of the realm of possibility for them.

Dear MRHers, Apart from the

Dear MRHers,

Apart from the fact that the TVD servo "Singlets" are so cheap, the following could work as a homebruise Server Driver circuit.

http://home.cogeco.ca/~rpaisley4/xServoTest555.html

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Servo Controllers

Good call Prof. Now scan further down the referenced page to the next circuit. It includes the switch which could be used for setting the points. Replace the single pole ON-OFF-ON with a double pole and use the second set of contacts to switch the power to the points.

DCC Servo controller

On Pacos's website you will find circuits for a complete DIY DCC system. There is a DCC Servo controller circuit.

This system is easy to build. I don't know anything about electronics and yet I was able to build the system from scratch. I think the Servopoint will be the next component I will build.

http://usuaris.tinet.cat/fmco/download_en.html#dcc

Resources please

Jim,

I found many references to 'how to convert a ATX PSU to a desktop power supply and it seems that all these are very similar in the way it's done. The one I used (see picture 'PSU Bench Unit.jpg' above) can be found at 

The article that I've based my experiments on is that same one mentioned in Rob's link - 'Turnout Motors from Servos.pdf' which is signed by Joseph Norris.

Neville

Part Number

Rob,

The unit I am experimenting with is a SF-90 but the model suggested by Joseph Norris in his article is the SG-90.

I have a problem with the SF-90 as it only starts to move at 1.2V whereas the SG-90 apparently starts to move at 0.5V.

Neville