Some notes about the servos.

Lack of experience in whatever area of expertise seems always to introduce problems of gigantic proportions until new experience proves such problems to be non-existent really. This was certainly true of my introduction to these servo thingies!

The electronic kits and instructions produced by MERG are so well designed that the part that I had originally been concerned about tackling, - soldering the tiny electronic components, - offered absolutely no problems. Not exactly ‘shake the box assembly’ but not far short. Well done MERG.

Unluckily for me, at the time of buying the bits, MERG had no stocks of servomotors. That raises no problem to those who have some knowledge of servomotors and their availability.

But for me? Phew!

A web search showed up such a myriad of servomotors, with prices and technical specifications of such a diversity as to be mind-boggling. Eventually I worked out that while the things I wanted were indeed servo motors, the type I wanted are more usually called “RC servosâ€, the RC meaning radio controlled. Even then there appears to be two standardised sizes when considering physical size, yet it seems possible to have a physically small one that will provide more torque than one of its larger brethren. All very confusing for a newby!

Friends from E4um and Manchester MRS helped me limp through this period of confusion and I eventually purchased five RC servos of two differing makes but of approximately the same physical size and torque. One was from a company called Protech, being their ref.no. B-305, and quoting a torque of “3.5kg/cmâ€, and being 41 x 20 x 36mm, in size. This one had been purchased from MERG and my thoughts were that it must therefore be suitable as a point motor.

The other four were by a company called “Zebraâ€; ref.no. ZS-S2113; torque 2.6kg/cm and 40 x 20 x 36.5mm. These had the same fixing centres as the Protech. I paid about £4.50 each for these but if you are prepared to buy on the web from sources in the far-east and on delivery times of about a month, similar servos are readily available at less than a quarter of that. My Protech was purchased from a friend at MMRS, who had it surplus to need and he got it via MERG. The Zebra were purchased from www.steveweb.co.uk who managed next day delivery.

For those of you who have even less knowledge than I had about servos I will try a little explanation. Firstly, don't concern yourself about the term "torque", just think of the number quoted as being a comparison figure of how strongly that particular motor will pull the point's tie bar. Secondly, we are all familiar with little electric motors which continuously spin through 360 degrees. Servomotors don’t spin, they simply turn a lever through a small angle. You chose the size of that angle, and the speed of movement by the setting process, which is then held in electronic memory.(whether that memory is in the servo or in the MERG ‘Servo4’ unit I’m not really sure but it is not important here). After that you switch the servo on and it moves the lever, and then when you switch it off, it moves the lever back to its original position. Now is that not what we want from the perfect point motor?

YES! It’s just all that electronic gubbins!?!, but no excuse,- MERG have sorted that for you.

I did meet up with some problems but they were of little real significance and easily solved: remember a previous post when I referred to that little red button in the top right-hand of the mimic panel?

OK I’ll talk about that next time, but mean while if you are interested in this subject then indicate so by 'comments' and ask your questions or correct my errors!