Servo Motors & Servo Controllers

[Steve Hewitt]

Many thanks for posting the very informative GF controls demo with your superb signals. I must confess to owning both a GF 2 way and 8 way board but I have yet to use them other than for testing purposes. I am hoping that the GF boards will be a bit more "refined" (is that the right word?) than the MERG boards as I do get the odd random strange noise from various servos in both the on and off positions with the MERG ones!

JF

Hi Jon,

 

I used to get quite concerned by the various "buzzes" coming from servos, but I've solved it by going partially deaf. 

 

Steve.

[Enjay]

Hi All

 

I've just spent today installing a PECO Smartswitch

 

I set up the first servo, it worked well, excellent slow control of a calling-on arm. I thought, this is nice, I like this.

 

I was setting up a second arm, and the whole thing went beserk, the display kept changing of its own accord, and the first servo starting swinging wildly.

 

It's pulled my signal kit apart, serves me right for trying to motorise a ratio kit, I suppose.

 

Not a happy bunny, wondering if those modellers who just have static signal models might just have got the right idea.

 

Anyone else had this problem?

 

Thanks

 

Nigel Beeton

[Jon Fitness]

Hi All

 

I've just spent today installing a PECO Smartswitch

 

I set up the first servo, it worked well, excellent slow control of a calling-on arm. I thought, this is nice, I like this.

 

I was setting up a second arm, and the whole thing went beserk, the display kept changing of its own accord, and the first servo starting swinging wildly.

 

It's pulled my signal kit apart, serves me right for trying to motorise a ratio kit, I suppose.

 

Not a happy bunny, wondering if those modellers who just have static signal models might just have got the right idea.

 

Anyone else had this problem?

 

Thanks

 

Nigel Beeton

Hi Nigel,

Well that should not happen!

I've not seen the Peco smartswitch in action yet, but the first thing to do would be try setting up a pair of servos that aren't coupled to anything to see if there is the same reaction.

If that still happens, swap the servos over and test again.

Have you got a few servos to test the set up with?

A few more things to check;

make sure the power connections to the unit are secure and of the correct voltage

make sure all switch connections are secure

check that the servos are still free to move at both ends of their travel as meeting a mechanical stop when under power can upset a servos electronics.

I can understand how frustrated you must feel to see your signal damaged but keep trying as working signals give a layout that bit of life, animation and realism that compliments the moving trains.

So keep trying and keep asking as I'm sure help is available on here!

Jon F.

[Suzie]

Have you got enough power for it? Servos can draw quite a high current and if you have more than one servo you will probably need a 2A supply at least to be on the safe side.

[Enjay]

Jon, thank you, you are quite possibly a genius.

 

The Smartswitch control board has terminals for the 12V power and for the SPST switches for operating the servos. Nice and easy to wire up, unless you are a ham fisted cloth head like me. I managed to leave one strand of the power cable to go astray, and I think it was shorting onto the board somehow, A touch of solder to keep the strands together (rather than just lazily twisting the wire)  and a more careful reconnection of the wires and all is well.

 

Anyway, I think the signal is repairable, the working signals project is on again, and the whole episode just teaches me to be more darn careful!!

 

Thanks again for your advice, much appreciated

 

Nigel

 

 

[Enjay]

Have you got enough power for it? Servos can draw quite a high current and if you have more than one servo you will probably need a 2A supply at least to be on the safe side.

 

Hi Suzie, the 12V supply is from a Gaugemaster controller model P, max output 12VA so 1 amp only. Oddly, Peco don't mention current in the otherwise excellent instruction booklet. There are moments when all four servos 'jiggle' to the centre position. As I've said to Jon the problem was my ham fisted wiring (I was laying on my back under the layout..).

 

The Gaugemaster is powering everything else (track, some Dapol signals, and point solenoids), so maybe I'm starting to push my luck. I was planning to use a separate power supply for lighting, as I have on another layout. It's doing OK at the moment but I'll bear your wise words in mind and look for a bit more power for the lights and then I'll connect the smartswitch to that and give the Gaugemaster a break!

 

Thanks again for all your help

 

N

[Jon Fitness]

Jon, thank you, you are quite possibly a genius.

 

The Smartswitch control board has terminals for the 12V power and for the SPST switches for operating the servos. Nice and easy to wire up, unless you are a ham fisted cloth head like me. I managed to leave one strand of the power cable to go astray, and I think it was shorting onto the board somehow, A touch of solder to keep the strands together (rather than just lazily twisting the wire)  and a more careful reconnection of the wires and all is well.

 

Anyway, I think the signal is repairable, the working signals project is on again, and the whole episode just teaches me to be more darn careful!!

 

Thanks again for your advice, much appreciated

 

Nigel

Good-o! Keep up the good (signalling) work!

JF

[bigal10]

Hi Steve and All,

 

Just started reading this excellent topic, (AFTER I started on my own use of servos using SwitchPilot / SwitchPilot Servo)

 

Thanks to Steve for the brilliant photos and videos, I saw your lovely Liverpool signal gantry being demo'd at Warley last year, and had a brilliant chat with your fellow club-member (and near neighbour of mine) who was demonstrating the use of servos with the GF unit.

 

This got me started doing my own, and having loads of fun, - and some tearing of what-remains-of-my-hair out !

 

Just to add my 2-penn'orth to some recent replies here regarding noise from the servos, I started out using TowerPro SG90's which are great and do 'everything it says on the box' but can be quite noisy in operation, as mine are mounted directly under the 9mm MDF baseboard, which of course acts as a brilliant sounding board!

However SG90's are a vast improvement over Peco and Seep, both in terms of noise, and in my opinion, the operation, which can be very slow if required, and more importantly move the point blades to exactly where you want them, and then lock solid in position.

 

I'm currently working on a motorised TensionLock uncoupling ramp, which I have shown on another thread, using a servo, and made simply from plasticard and plastic tubing, and, using SWP Extension have placed an indicator lamp near the ramp, to show when it is in the up position.

 

In one of Steve's earlier posts in this thread, you mention that you've tried various different servo's, so I have shopped around and found E-Sky (at RC Mods in Waterfoot) which are very quiet, even on my 'MDF soundbox'

The E-Sky is a bit more expensive than the TowerPro but as it is 'digital' it is very controllable from ECoS with SWP Servo.

 

Keep up the good work, and Steve, don't eat too many of Baxenden's best export!

 

Regards,

Alan

[Steve Hewitt]

Have you got enough power for it? Servos can draw quite a high current and if you have more than one servo you will probably need a 2A supply at least to be on the safe side.

 

 

Hi Suzie, the 12V supply is from a Gaugemaster controller model P, max output 12VA so 1 amp only. Oddly, Peco don't mention current in the otherwise excellent instruction booklet. There are moments when all four servos 'jiggle' to the centre position. As I've said to Jon the problem was my ham fisted wiring (I was laying on my back under the layout..).

 

The Gaugemaster is powering everything else (track, some Dapol signals, and point solenoids), so maybe I'm starting to push my luck. I was planning to use a separate power supply for lighting, as I have on another layout. It's doing OK at the moment but I'll bear your wise words in mind and look for a bit more power for the lights and then I'll connect the smartswitch to that and give the Gaugemaster a break!

 

Thanks again for all your help

 

N

Hi Suzie, Enjay,

 

From what I've observed and learnt from others:

Usually better to use a separate supply for the servos.

The servos only take a significant current when actually moving. Almost none when holding station.

Good "Switch Mode" power supplies are readily available from the likes of Maplins.

 

I actually use one that used to power a portable TV / Monitor.

Rated at 2 amps, it happily powers all the servos on my Demo stand - sometimes up to 20 servos, but rarely more than two moving simultaneously.

 

Steve.

[Simond]

Hi all

 

As an alternative to the Peco, Switchpilot, MERG and GF servo controllers, I & many others have been playing with Arduinos.

 

There is a thread "Arduino Applications & Programs" containing some servo control programs for signals, points, and stepper approach to turntables - link in my signature below. The Arduino approach is certainly cheap and very flexible, but does require some programming.

 

Hope this helps

Simon

[Steve Hewitt]

Next Saturday I'll be demonstrating at the 0 Gauge show at Leigh.  http://nwogm.org.uk/2014-show-details.html

I'll have several servo control systems with me - Embedded Controls, GF Controls, MERG, Switchpilot.

Just come along if you want to play with any of them, or just stop by for a chat.

 

Steve.

[LNERGE]

So near yet so far. I'm on a 12 hour day shift at Chat Moss.

[Jon Fitness]

Next Saturday I'll be demonstrating at the 0 Gauge show at Leigh.  http://nwogm.org.uk/2014-show-details.html

I'll have several servo control systems with me - Embedded Controls, GF Controls, MERG, Switchpilot.

Just come along if you want to play with any of them, or just stop by for a chat.

 

Steve.

I'll hopefully be there, but it will be after a 12 hour night shift so I maybe a bit zombie-like!

JF

[Steve Hewitt]

Home again from a great day at Leigh demonstrating at the 0 Gauge North West event.

 

I managed a total of four soldered joints in a full day!

Two short brass tubes attached to etched plates to make two arm bearings, plus One spectacle plate attached to its arm, and then the arm pivot added.

Such productivity will get me a bad name.

 

Great to chat with Jon Fitness and Derek Mundy.

We're always trying to pick each others brains - there'll be nothing left shortly.

 

Steve.

[meowenuk]

Leigh O Gauge North West show.

Hi Steve - My brother and i paid a visit to your stand at the show (Utility Warehouse - remember?). Very helpful in getting to grips with servos versus point motors. Have joined MERG - amazing amount of info even to a novice Very impressed. Now waiting for further stock of Servo4 kits to be available.

Thanks for your help.

Mark

[Steve Hewitt]

Mark,

 

Thanks for your comment.

Glad to have been of some help.

It's nice to hear that someone has benefitted from a show demo.

Often spend all day talking and encouraging modellers to "have a go", but not usually sure its been fruitful.

 

Steve.

[Simond]

Hi all

 

Thinking of the day when I will need a power supply to run signal & points servos, a desktop ATX power supply seems like a useful option.

 

http://en.wikipedia.org/wiki/Power_supply_unit_(computer)

 

Prices from about £13 for 500W, which should be enough... (Though this is split between 3.3, 5 & 12V, all of which are regulated and over-current protected)

 

Anyone tried it?

 

(A check on the search did lead to a thread from 2010 largely promising death & calamity to anyone who even considered it - I was hoping for a less sensational response)

 

Best

Simon

[Trofimow]

Hi all

 

Thinking of the day when I will need a power supply to run signal & points servos, a desktop ATX power supply seems like a useful option.

 

http://en.wikipedia.org/wiki/Power_supply_unit_(computer)

 

Prices from about £13 for 500W, which should be enough... (Though this is split between 3.3, 5 & 12V, all of which are regulated and over-current protected)

 

Anyone tried it?

 

(A check on the search did lead to a thread from 2010 largely promising death & calamity to anyone who even considered it - I was hoping for a less sensational response)

 

Best

Simon

 

I've been using old ATX psu's from redundant computers for some time for just the purposes you propose, plus lighting.

 

Zero cost as they would have been disposed of anyway. I've taken the precaution of fitting in-line fuses in the outputs, and have not suffered death and calamity (so far). Works fine for me but then I've not seen the thread you mention....

 

Alan

[Simond]

Alan

 

This thread

 

http://www.rmweb.co.uk/community/index.php?/topic/9726-using-an-atx-computer-power-supply/

 

Best

Simon

[Trofimow]

Alan

 

This thread

 

http://www.rmweb.co.uk/community/index.php?/topic/9726-using-an-atx-computer-power-supply/

 

Best

Simon

Thanks for the link, Simon.

 

Having read carefully through the various comments, I am still comfortable with the way in which I am using the unit, and the purposes for which I am using it, and there do seem to be others doing similarly.

 

The warnings expressed in the thread are valid, particularly regarding the voltages inside the case, whch I have no intention of opening up, and the point about the supply 0v being the same as mains earth.

 

Yes, they can also have a limited life expectancy, and in a few years of building and looking after PC's including on a commercial basis, I've seen quite a few go bang, some quite spectacularly, but the better quality (read more expensive) units do generally seem more reliable.

 

I can't advise you whether to use one or not, but you do need to understand the potential implications if you choose to do so.

 

Alan

[Simond]

Alan

 

Thanks for your thoughts.

 

I shall use a computer PSU at least as an experiment. I'm certainly not going to open it up, so that's not a concern (any more than I'd be worried about having a valve guitar amp or an old-fashioned CRT TV), but the zero volt thing is an interesting point - probably not an issue for point & signal control, or lighting, but probably well worth avoiding for track where multiple feeds are envisaged - and where human contact might be expected to be the norm, eg for track cleaning. Shouldn't be a single point of failure risk, but could make another failure worse, perhaps.

 

Thanks again

Simon

[50031Hood]

I know this forum has been quiet of late but I thought I'd add the results of my experimentations. I initially experimented with 5V DC motor/gearboxes to create a point motor but despite making several working prototypes, there were still far too many components involved and far too much soldering. Following the advice on this forum I took the plunge and ordered 6 Tower Pro SG90 servos. By chance I came across Rob Fryers excellent Bath Spa blog in which he described making a mounting bracket for the self-same servos to control points. Rabs kindly sent me his CAD drawings and I used the dimensions of these to make my own pared down version described below.

This shows the holes drilled through the 4mm baseboard that I will be using. There are two countersunk 2.5mm holes and a 3mm hole for the wire to switch the point.

This shows the laser-cut mounting plate located with two M2.5 machine screws. Incidentally, the mounting plate is used as a template to mark the holes in the first instance.

The machine screws pass through the servo and are secured using nuts and a 1mm steel wire passed through the servo arm and a hole in the mounting plate.

 

And this is what it looks like from above, ready for the point.

For me the interesting part is controlling the servo which is done using a PICAXE kit, specifically to drive servos. These are reasonably priced (approx. £5 to connect up to 4 servos) and the software to control them is a free download. The movement of the servo is determined by the software which means that altering the throw of the point is a quick software update. How cool is that?

[Siberian Snooper]

 

I know this forum has been quiet of late but I thought I'd add the results of my experimentations. I initially experimented with 5V DC motor/gearboxes to create a point motor but despite making several working prototypes, there were still far too many components involved and far too much soldering. Following the advice on this forum I took the plunge and ordered 6 Tower Pro SG90 servos. By chance I came across Rob Fryers excellent Bath Spa blog in which he described making a mounting bracket for the self-same servos to control points. Rabs kindly sent me his CAD drawings and I used the dimensions of these to make my own pared down version described below.

photo 2.JPG

This shows the holes drilled through the 4mm baseboard that I will be using. There are two countersunk 2.5mm holes and a 3mm hole for the wire to switch the point.

photo 4.JPG

This shows the laser-cut mounting plate located with two M2.5 machine screws. Incidentally, the mounting plate is used as a template to mark the holes in the first instance.

photo 3.JPG

The machine screws pass through the servo and are secured using nuts and a 1mm steel wire passed through the servo arm and a hole in the mounting plate.

photo 6.JPG 

And this is what it looks like from above, ready for the point.

photo 7.JPG

For me the interesting part is controlling the servo which is done using a PICAXE kit, specifically to drive servos. These are reasonably priced (approx. £5 to connect up to 4 servos) and the software to control them is a free download. The movement of the servo is determined by the software which means that altering the throw of the point is a quick software update. How cool is that?

 

 

Can you please give details of the PICAXE kit used, I have had a bit of a shufti on the website, but being a complete novice in these things, I have no idea of what I'm looking at.

 

TIA.

[50031Hood]

Can you please give details of the PICAXE kit used, I have had a bit of a shufti on the website, but being a complete novice in these things, I have no idea of what I'm looking at.

 

TIA.

This is the servo kit: http://www.rapidonline.com/design-technology/picaxe-08m2-servo-driver-kit-13-5054

and to program it you will need to hook it up to a computer with one of these: http://www.rapidonline.com/Design-Technology/Electronic-Components/Integrated-Circuits/PICAXE/PICAXE-Cables

The software that I used is called Logicator. I prefer it to writing basic because it is visual - drag-and-drop - plus the download includes a manual which tells you how you can control servos. Good luck!

[Grovenor]

Here's a video of a demo unit using the same principle, http://youtu.be/zcKRknQ2Hew?list=UUWRbJ7me2ffZKQiA3L0mO7g

Uses a bit of B&Q aluminium angle but I think your bolt arrangement is a bit simpler. What I don't see on yours is how you are preventing the 1mm wire dropping out?

I use a piece of heat shrink sleeve over the wire.

Keith