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Saturday, 15 August 2009

Maplin Steam Engine Sound Generator (MK134) Review

Those familiar with my main model railway web site will know that I use recorded engine sounds played from a PC to accompany my model train train movements. This is fine for trains starting off or in full motion but shunting is another matter. Shunting engines move very slowly with frequent stops and starts. So, this inexpensive electronics kit from Maplin provides an answer.

The generator has an on/off switch, volume, speed and whistle controls. It is powered from a 9V battery, but could be powered from an AC to DC adaptor up to 12V easily.

When switched on and the volume turned off a continuous hissing sound is still heard, reminiscent of a stationary engine leaking steam. As the volume is increased we hear the beat of the engine in motion and adjusting the speed control we can emulate the speed of the engine from a crawl to the fastest express.

A more 'basey' sound can be achieved by placing the speaker at the end of a long cardoard tube (mine is about 3 feet) and baffling the rear of the speaker with a pair of socks - one inside the other placed over the rear.

The steam sound is realistic and works well for the shunting movements I intended it for.

The Whistle on the other hand is not realistic. It lacks the sound of the steam rush of a real locomotive whistle. It sounds electronic - too pure.

The Kit

The instructions are in the step-by-step pictorial format. There is scant textual information for the uninitiated about how to tackle an electronics assembly.

Component values or identities are either colour coded or stamped on the body with a very small number.

Some of the components, especially resistors cover up their circuit number on the PCB (printed circuit board). So, if you put one in the wrong place and need to remove it you have to work out from the supplied circuit diagram and the track runs on the PCB which one it is!

Four pins are supplied which are soldered to the battery connector and speaker connection points on the PCB and then the battery and speaker wires soldered to them. These are pointless and fiddly - throw them away and wire the cables directly to the PCB.

As with all electronics, if it don't work when you switch it on then you are pretty much stuffed without electronics technical knowledge and diagnostic equipment. All you can do is check the components were fitted in the right place, all the wires are firmly soldered to the PCB pads and there are no solder bridges between components where not meant to be.

Battery not supplied. Use a new one, not one previously used.

Kit Assembly Rating 1-5 (5 easy, 1 difficult)

Experienced in electronics assembly with understanding how it works: 5
Have built electronics successfully before but not knowledgeable in how it works: 4
Never built an electronics kit but have used a soldering iron: 3
No previous experience whatsoever: 2 (give it a go anyway)

Tips

1. Follow the step-by-step instructions precisely. Note the colour code provided for resistor colour banding value identity.
2. Having pushed a component through the pcb splay out its legs so it does not fall out when turning the assembly over.
3. Apply the soldering iron to the component leg and its PCB pad then about 1 second later apply the solder to the joint side furthest from the soldering iron - not to the bit of the iron.
4. Solder in place the group of components from a step of the instruction and cut their leads short before moving onto the next step.
5. Use a magnifying glass to check the solder joints are shiny, cover the PCB hole and not bridging other component leads where not meant to.

Tools Required

Essential: Small electrical wire cutters, soldering iron with fine point, electrical fluxed solder.
Helpful: Small electrical pliers, magnifying glass, solder removal pump or copper braided wick.
If it don't work: Multi-meter, oscilloscope.

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