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  1. duke37

    Charging Few Battery pack in once. Help!!!

    Six CELLS in series to give 12V means each cell is 2V. What type of battery is this? Lead - acid? Putting batteries in parallel will give the capability of more current but the current will depend on what the load demands. You cannot charge them to limit the output current. A fuse close to the...
  2. duke37

    Bought a cheap soldering iron - should I be concerned about this?

    Soldering iron bits are often iron plated which should not be removed so treat with care. If the iron plating is damaged, you will need to reshape the tip with a file and retin the tip often as the solder dissolves it.
  3. duke37

    Help for a Project please!

    The LM3914 should do what you require. You do not need a relay for low power leds. The resistor chain is inside the chip. It would need a simple stable power supply. It can be set to turn on one led at a time or give a 'thermometer' display.
  4. duke37

    Curious inductor question

    You cannot get a pure inductor, it will always include capacitance due to the adjacent turns. This results in a tuned circuit which will resonate at some frequency. A 30k resistor may well damp this resonance so that the effect you see is eliminated. Wave winding can be used to reduce the...
  5. duke37

    Convert a 6 volt to 12 volt on my motor cycle . Any ideas how that's done

    There is a resistor allied to the magneto which is switched. Presumably this is a charge rate adjuster but without detailed information it would be impossible to see how this could be improved. The simplest way out of the problem would be to change from bulbs to LEDs with appropriate control...
  6. duke37

    Convert a 6 volt to 12 volt on my motor cycle . Any ideas how that's done

    You have not said why you wish to do it. Please post a schematic of the wiring, the one I tried to download locked up my computer. It should be possible to provide 12V for ancillary devices but would take a lot of effort and cost to convert the alternator and ignition
  7. duke37

    Mosfet heater control

    I wrote a response to AgilePreanut but it went in a different thread.
  8. duke37

    Mosfet heater control

    My first thought is the you do not need a rectifier, you could use a solid state relay (SSR) to switch the heater. Many, many years ago I was using a thermocouple with a radio frequency heater. I made a low pass filter which did the job for me.
  9. duke37

    Basic adapter no output

    The thermal fuse takes into account the dissipation in the transformer. An external fuse can never do this. You seem to think that the transformer is basically OK. One likely fault is that there are shorted turns. The wire has a very small diameter and the insulation is very thin. If two turns...
  10. duke37

    Basic adapter no output

    You could fit a very low current fuse but may not find anough space to fit it. Try connecting across the fuse and, without load, check whether the transformer heats too much. Do not leave it unattended and do not touch any mains terminals.
  11. duke37

    Basic adapter no output

    This looks like a fuse as suggested and not a resistor thus it should have a very low resistance. It is rated to 130 degrees C. Why did it blow? Was there overload of the output or did the primary winding fail with a shorted turn? If the winding is faulty, can you rewind it? Can you solder in a...
  12. duke37

    voltage dropping

    I do not see how the logic system affects the power supplies. You have several alternatives. 1. Two power supplies. 2. A 12V supply with a buck convertor to give 5V also. 3. A 5V supply with a boost convertor to give 12V also. 4. A pre-built supply which gives both outputs (computer power...
  13. duke37

    Need Help regarding 12v DC Motor

    What is a REd pump? If your engine runs at 3000rpm, then I suspect that it is driving an alternator to give 50Hz like the mains. How do the pumps manage to draw from 150ft? The energy must be put in at the bottom of the well. A centrifugal pump will probably need a power input proportional...
  14. duke37

    Need Help regarding 12v DC Motor

    No. The maximum suction is about 30ft, 25 is much better. To do this you will need a foot valve so the pipe is always full of water. Get a bore hole pump or bilge pump which can be lowered down into the water so that priming will not be a problem. Get one with plenty of head to spare. Use a...
  15. duke37

    Question about battery in vintage anemometer

    There is likely to be a transformer, rectifier and voltage stabiliser. It is the output of the stabiliser that you want. A picture of the works close to the transformer could give quite a bit of information. What voltage are the bulbs? What voltage are the smoothing capacitors?
  16. duke37

    Question about battery in vintage anemometer

    If the battery fits inside the unit, then find what batteries fit. If the battery is external then power it up on the mains and measure the supply voltage provided. Be very careful if you have not dealt with mains before.
  17. duke37

    Best Way to Splice a Wire?

    Rosin cored solder should be used. No NOT use plumbers flux, this is often acidic which will corrode the wire in time. I have an antique tin of Fluxite to be used in difficult cases and a jar of LA-CO fux paste which seems to be sumewhat more effective. The makers will not tell me if it can be...
  18. duke37

    90 degree turn servo and controls

    I would think that a solenoid, which only needs turning on and off, would do the job of a servo. You will need some way of producing a random signal. Have you thought about this? Will you be picking up all the lead shot? I am discouraged to use a smidgeon of lead in solder.
  19. duke37

    Sound activated alarm

    Radio amateurs have repeaters on hills to retransmit signals and enable communications over longer distances. The repeaters were turned on by a tone in the received signal. Early tranceivers did not have tone generation circuitry and some amateurs with good pitch would whistle up the repeater...
  20. duke37

    Speaker box project. Need a little help

    You have three switches there, which do you mean? Please redraw your schematic with a common rail along the bottom and the mains and low voltages separate. I do not know what the bolt in the centre is.
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