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Upon Not Finding a Socket Near to Your Table!
By Les Chatfield
This all started when I decided to exhibit my Meccano models at the Brighton Modelworld exhibition for the very first time. Being concerned as to whether my elderly trainset controller would pass its PAT Test or whether there would even be a suitable socket nearby I decided to investigate running my models on batteries — rechargeable batteries!
The entire system, with the battery 'charger' holder to the right, the switching unit at centre and two speed/polarity controllers to the left.
Of course, if only one model is to be powered the switching unit can be dispensed with and the controller connected directly to the battery holder as if it were a transformer.
Most batteries available seemed to have several issues preventing their use for running Meccano models such as fumes, the dangers associated with modern LiPo batteries and also expense. I was just thinking of abandoning the project when I thought "Why not use cordless drill batteries?" By chance I have several batteries for my drill and started considering how one might connect leads to it to run models!
To this end I obtained an old drill battery charger, carefully opened it up and removed nearly all the 'works' from inside. I left only the battery connector contacts and the mains lead. I removed the 13A plug as it would never be plugged into the mains again (if it has a bonded-on plug then cut it off but make sure you throw the plug away). I soldered the live and neutral wires of the mains lead to the battery contacts inside the charger's socket.
A quick check was carried out with a multimeter set to Ohms to make sure there were no short circuits or misconnections. All seemed well so I connected the charger's cable to a Meccano Powerdrive motor, placed a battery into the 'charger' and hey presto the motor whirred into life! But too fast! (My particular battery delivers 18 volts). So I obtained a model railway 'circuit controller' which is a speed controller without a transformer and is designed to be connected to a separate transformer. This was connected between the Meccano Motor and the drill battery in its 'charger'.
This has turned out to be the answer — perfect control and a day's running from one battery. The tiny motors Meccano modellers use are a fraction of the size of a cordless drill motor so a drill battery will run such motors for a considerable time. Plus, of course, the DC voltage is considerably 'cleaner' and 'smoother' than the DC from a transformer and, as a final plus point, should you be running an old E15R motor (notorious for knocking out every TV within a hundred yards) you will find the interference much reduced as you are no longer connected to the mains!
In use this system has proved itself to be completely reliable and I have found that one drill battery will run two or three large Meccano models throughout an exhibition. Should the battery require changing this is accomplished in seconds. Pull one out and push another in.
At one exhibition after a power failure I was the only one left running models to the chagrin of other exhibitors. I have used my battery system for the last two years and it has caused no problems at all…
…and no more hunting for power sockets!
» This article appeared in the September 2013 issue of SELMEC News.