The Dapol M7 takes off like a rocket if powered from a traditional Hornby train set controller. The long term plan is to use DCC but whilst the layout is being constructed we needed a simple controller that provides authentic slow running for engine/track testing.Dapol recommend a 9V DC controller specific for N gauge use. I have a box of spare electronics components so, I did a quick search on the www to find a simple controller circuit diagram, and here it is. I choose the 'Step 2' circuit showing a Darlington pair transistor arrangement with fuse for short circuit protection. A root through my box of electronics revealed the required components, albeit I used a 2N3904 for TR1 and 2N3440 for TR2.
There is an error in the circuit diagram for the double pole switch. If you look carefully you'll see it creates a short circuit as drawn! The wiring of it should be a mirror image with the output leads going to the wiper contacts of the two poles, not the feed.
My assemblage of the design is a bit rough but serves our immediate need for slow to fast running of the M7. Just need to be careful we don't short circuit the track, else the fuse will blow. Only one spare left in my box of bits.
David
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