Time to add some wires to Polar Bear. The basic circuit is pretty simple - batteries wired to the motor via a DPDT switch which will handle direction and on/off duties.
There is an added complication that a pair of giant LEDs will be fitted in the ends. These will light up in the direction of travel. Looking at the diagram which is partly neatly drawn but has hand draw extras for this lighting, I can see a few people being confused.
It IS correct, but you need to realise that the long and short legs of the LED aren't the same. They show up on the drawing if you know what you are looking for. There's an extra wire to the switch too.
Once set up, all worked well. Until I put the switch support box back in. Then the loco ran properly in one direction and very slowly in the other. Take the box out and all was well. After a bit of head-scratching, I realised that the box was pushing the LED legs together so when the model worked in one direction, there was a weird short circuit. Pulling the legs around so they no longer touched and all was well.
1 comment:
"Once set up, all worked well. Until I put the switch support box back in. Then the loco ran properly in one direction and very slowly in the other. Take the box out and all was well. After a bit of head-scratching, I realised that the box was pushing the LED legs together so when the model worked in one direction, there was a weird short circuit. Pulling the legs around so they no longer touched and all was well."
Just for future reference, an alternative approach might involve insulating all the wires / connections before putting the box back together, to reduce the likelihood of accidental shorts.
Perhaps the most obvious example of this would involve the use of tubing or insulating tape over individual wires / joints. This would certainly work - especially if you had the chance to remake connections.
Otherwise, I'd be tempted to adapt an approach I used a lot in my last job, when fitting starin gauges to specimens. Once I'd fitted / soldered wires, I usually painted over all connections with a quick drying lacquer - this usually meant something closely resembling clear nail varnish (although something coloured might work even better, as it would be obvious if any connections hadne't been treated, or needed a second coat). This stuff usually took a few minutes to cure - but made an enormous difference.
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