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  1. duke37

    Test Rig, Need Advice

    This seems to be a common problem. My neice has just had a module repaired by "The James Clan" for £30. This includes water proofing. It works well but do not know for how long.
  2. duke37

    Run a wifi station and IP camera off of landscape lighting power?

    For 12V AC to 24V AC get a transformer with a 12-0-12 V secondary. Put the input to 0-12V and the output to 12 and 12V. The original primary is not used but could bite you.
  3. duke37

    Time of current rise in a coil

    If I interpet what you have correctly, the current will only rise to 2.6A. Any resistance in series with the coil needs to be added to the coil resistance. To get 5A the total resistance will need to be less than 3Ω.
  4. duke37

    LIghtning induced power surge signs/symptoms?

    I have repaired some battery driven electric fencers in the past. Lightning damage can vary between no visible damage and one component not working correctly to all the insides of the box being blown apart. The prettiest failure was where several diodes had split in half and the ends were...
  5. duke37

    Help with functions for my circuit

    Am i seeing things, or do you have a capacitor in series with a battery?
  6. duke37

    Water level Controller - Arduino Based

    You may be better off to earth the water tank instead of trying to hold it at 5V above earth. It depends on what the water system is connected to. The detectors should then be held at 5V through a 100k resistance and the voltage out would drop when the water contacted the sensor.
  7. duke37

    Need help with DC motor

    Some information required. 1. Voltage and current 2. Number of connections. 3. Permanent magnet or electrical field. 4. Series or parallel connections. 5. Speed signal output. Much of this information may perhaps be obtained from the treadmill circuit diagram together with a suitable speed...
  8. duke37

    inverter transformer parameters

    I do not see how your calculations work. Also you have not specified waveform or frequency. Look up 'ludens transformer', he gives details of flux density in the core and current density in the wire. There is a good exposition on how to wind the transformer.
  9. duke37

    Soldering and veroboard HELP!!

    Make sure the components are oxide free. Old components and board can be difficult. Put a small amount of solder on the iron tip so that good thermal connection is made when touching the joint. Heat the component and place the solder away from the iron. The solder will flow towards the heat. Use...
  10. duke37

    Testing capacitors in amp circuit

    Large capacitors are measured by inputting a small current and then measuring the rise in voltage. If the capacitor is leaky, some current is lost so the voltage rises more slowly as would a higher value capacitor. Measure the leakage current at rated voltage.
  11. duke37

    Wanted: Nuts for AVO coil winder

    A pair of traverse half nuts for an AVO coil winder required. These fit a 0.5 inch diameter 40tpi shaft with a buttress thread form. Alternatively has anyone got a suitable tap?
  12. duke37

    Switching power supply

    There are two limits for your power supply, 12V and 30A. Going beyond either of these could lead to trouble. The internal components will have voltage and current limits. You may be able to get away with a few more amps if cooling is very good but you are skating on thin ice and the high current...
  13. duke37

    Fault from powering with incorrect voltage

    This is more complcated than I thought. The anion generator could be a problem if it has been overvoltaged. You will need to draw out the circuit diagram and remove suspect components to isolate the fault. Do not scape off the green covering, it helps the insulation. Only bridge contacts if...
  14. duke37

    Arduino Air flow meter (low speeds)

    You could get fine wire in a low current fuse. The ends should be fixed and then the glass broken and removed. A good fuse would provide the comparison.
  15. duke37

    Fault from powering with incorrect voltage

    There are very few components abd they are all labelled. I would think the switch is faulty, check that the switch is making a contact with a meter. The solder on the switch looks as if it has been overheated which could happen it the switch does not turn on fully.
  16. duke37

    wanted : 12vdc to 24vac 5 watt schematic

    You do not say what frequency or votage accuracy you want or the waveform. A simple supply can be made with a centre tapped transformer driven by two fets and controlled by a 4047. There will be approximately 24V square wave across the entire winding. There may be problems with isolation.
  17. duke37

    Plastic bender

    A Variac will be good to vary output but must NOT be used direct since it is not isolated. You could use a Variac to drive a transformer or old style battery charger. I know of a lamp dimmer being used instead of the Variac but you may get trouble from transformer saturation. A series bulb in...
  18. duke37

    HELP WITH UNDERSTAND OF NAND GATE CIRCUIT?

    It would be handy to know what the circuit is supposed to do. I have not worked out what the first two gates do, probably produces a timed pulse defined with the capacitor. Gate 3 is an inverter to get the polarity right. Gate 4 is an oscillator with a frequency of 2.7/(R*C) to make the led...
  19. duke37

    line voltage

    A sine wave varies its voltage up and down. The voltage of the supply is quoted as the same as would produce the same average power as DC in a resistor. This calculated as the root mean square (RMS). It follows that at some times the voltage will be above the RMS and at other times it will be...
  20. duke37

    How to build SMPS

    I have made inverters to produce AC at 400V or so which when rectified produce the high tension for radio sets. I used the ferrite cores from TV line output transformers and wound them with 1 turn/volt and run at 10 kHz or so. I think that the problem is the definition of inverter. It can be...
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