Any electronics geniuses here?

Discussion in 'HO Scale Model Trains' started by vanda32547, Apr 26, 2006.

  1. vanda32547

    vanda32547 Member

    Is anyone here electronics literate? I wanted someone to look over this diagram and see if I am on the right path. Since I am not into electronics I could use some expert advice.


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  2. jim currie

    jim currie Active Member

    not a geniuses but what are you trying to do ?
  3. vanda32547

    vanda32547 Member

    I am trying to take a 12volt/12amp power supply that illuminates 12v40mA grain of wheat bulbs and split it out to have 3 seperate circuits one with 3 volts, one with 6 volts and one with 9 volts to control the amount of power each light bulb receives. This way being able to control the look of each circuit. Don't know if you can tell by the image but each circuit is controlled with a 50 ohm wire wound potentiometer. Also there is a 10 ohm resistor at the front end to prevent a dead short. I plan on using many lamps in this project and my power source, I have been told, should handle a couple hundred lamps. Any help, insight or opinions would be greatly appreciated.

  4. Joepomp

    Joepomp Member

    It been a long time!

    It been a long time, but I think I smell a voltage divider ckt.
    Ill have to think about it.sign1
  5. GeorgeHO

    GeorgeHO Member

    It looks to me that they will do what you want, but my knowledge is from the dark ages. Each one of your throttles can be adjusted to whatever voltage you want. I assume you can look at your lights and tell from how bright they are if they are getting the proper voltage, then just make an adjustment. The current going through the wire wound pots is wasted energy. If you dont need to vary the voltage when the devices are in use, it's better to run your 9v and 3v in series (if the resistances are matched) and not use the pots at all. If you are using the pots as dimmers, or selective on/off switches, then they are needed, and should do the job.
  6. jim currie

    jim currie Active Member

    first off how many lamps total are you planning to run in this circuit? and you would be better off putting a fuse or a mini braker in place of the 10 ohm resistor(R1) as the more lamps you put in the more voltage loss will happen at R1 .as drawen you would need a 165 ohm resistor for the first leg to get 3 volts on lamp one i think .:)
  7. shortliner

    shortliner Member

    You'd be better using an LM3909 voltage reg for each circuit
  8. Pitchwife

    Pitchwife Dreamer

    For what you are doing, just running lights, I wouldn't worry about ICs and I wouldn't use wire wound pots (potentiometer). Get yourself some 1K linear taper pots. They will have three legs. Wire them up as they are in the diagram and you shouldn't have any problem adjusting your lights. You can add as many as you want as long as the total current doesn't exceed your power supply's rating. Any RS or other place that caries electronic components will have the pots and they shouldn't set you back more than a buck. If you are just running one light on each circuit, a small wattage rating will work fine. I would put a fuse in place of your top resistor though, the size to be determined by the number of lights.

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