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Crosland

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    www.sprog-dcc.co.uk

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    Warwickshire, UK
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    DCC 2mm

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  1. I would agree with that. Power control (removing th control pulse) is for curing chattering servos that are trying to drive against the endstop of whatever they are connected to, and draw a lot of current. This doesn't work for digital servos that continue to drive even when control is removed. It can also be cured by using flexible linkages such as omega loops. Power sequencing can be useful at start up when a lot of servos may be moving at the same time. This can result in the supply being overloaded. Ah, but 50% of MERG members will swear blind you need pull-ups to set the inactive level Are there two schools of thought here? DId you keep the servos isolated, with their own supply, or common the 5V and Gnd as per junctionmad's solution?
  2. Looks like you used ohms law R=V/i and calculated 12.5/.33. You need to subtract the voltage across the LEDs? Still a high power dissipation though
  3. The OP said it's 12.9V DCC. The rectified voltage will be slightly less than this due to the losses in the diodes. It doesn't matter whether you measure on load or not. If you are rectifying the DCC in a lot of coaches then you should really use fast recovery diodes or bridges to avoid distorting the DCC waveform.
  4. A T1 will be twice the price of the equivalent from somewhere like Rapid Electronics.
  5. The apprentice uses bulbs without thinking. The journeyman avoids them without thinking. The master uses them thoughtfully.
  6. You could make up custom batteries using rechargeable AA cells in battery holders. Rechargeables have a lower internal resistance and so can supply more current without the voltage drooping as much (just don't leave the magnet energised for too long) and an AA based pack will last a lot longer than a PP9. USe Eneloop or equivalent, rather than NiCads to avoid self discharge.
  7. If you mean directly off the DCC track bus then be aware that it's very different AC (frequency and waveform) from what you were using before. It's not surprising it doesn't work. You should never connect anything like this directly to the DCC bus. What current does the magnet take when energised? I would not recommend powering any potentially high current devices like this even from a rectified DCC bus. If you booster is not conservatively rated for your layout then operating the magnet could affect the running of trains, due to the extra current required. You would be far better off to buy a cheap "wall wart" style power supply suitably rated for the magnet. That note about rectification is potentially very misleading. Rectifying normal 16V AC would give you nearer 22V DC, not 12V! What exactly do they mean by "nominal" 12V? You would also need a regulator if the magnet really is rated for only 12V.
  8. ??? DCC is a square wave so no need to average or detect peaks or do any RMS calculation. As already said, a simple bridge rectifier is more than adequate.
  9. I have thought of a DCC-DMX accessory decoder for controlling layout lighting rigs but I think DMX is closed source and I was too tight to buy the spec There's also DALI which has hardware support in some PICs. I would like to see those waveforms zoomed in a bit, and/or sampled at a faster rate, hence my earlier comment.
  10. That photo prompts a question: How long has the double square symbol been in use?
  11. If you want to retain your sanity, don't look at a DCC waveform with a 4GHz scope
  12. Shortening the pins won't make it fit in any better but beware some sockets can allow long pins to stick out the other side and short out on metalwork. So shortening can prevent shorting
  13. The 2mm Scale Association Track book shows how to make some very simple filing jigs that could be adapted to other scales.
  14. I remember in the days of 405 line TV our picture turning to snow when a neighbour 6 doors down (honestly) revved his car. You will find very few cases these days. A lot of cases of interference, especially TV, are due to poor receiving equipment, e.g., years old, corroded, aerials and downleads. Wires just poked in the back of the aerial socket, etc. The move to digital caused a lot of such stuff to be upgraded, e.g., where the digital signals were in a different channel group, so TVs are a lot less receptive to interference. In the digital world, fitting a decoder means that the wires from the motor are much shorter and not directly attached to the track, so the facility for commutation noise to be broadcast via a layout sized aerial is much reduced. <pedant mode> Suppression components are not actually a legal requirement. The legal requirement (when sold) is that the equipment (i.e., the loco) does not radiate excessively. What you do to it in your own home is up to you, so long as you do not spoil other peoples enjoyment of the Archers </pedant mode>
  15. The "proper" way to use screw terminals is to crimp a bootlace ferrule on the end of the wire. It will not flow under pressure from the screw like solder can, coming loose over time. In your case it will probably just exacerbate the problem with the small connectors. There's no harm in using a very short run of thinner wire from the connector to the thicker wires. Any voltage drop will be minimal over an inch or two.
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