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  1. C

    Transformer; How do I calculate turns and volume.

    You just said you want two windings. That is a transformer. What frequency do you want?
  2. C

    output of rain sensor

    You cannot get precipitation values from a resistive grid. You need a catchment vessel that has a 10:1 or 100:1 collection. When it reaches a certain volume, it automatically tips over and the "tips" are counted. Here is the principle:
  3. C

    Transformer; How do I calculate turns and volume.

    To save wading through a mass of information, the first thing we want to know is the wattage of the transformer.
  4. C

    automatic power off problem in DMM

    Maybe the battery is flat.
  5. C

    Running high current electric solenoid using a H-bridge

    Don't try re-inventing the wheel. Go to the person who produced the video and ask for the details of the invention.
  6. C

    Heating a steel strip with current? 'hot knife'

    Use a material with the highest resistance so that you require the least amount of current. Nichrome (NiCr) is the best because it is cheap and oxidises the least. Just use the table for comparisons - don't worry about the actual values.
  7. C

    Heating a steel strip with current? 'hot knife'

    The secret is to use thin wire or flat wire that has a lot of resistance. That's why you use "radiator wire" from an old radiator or toaster. Then it will work.
  8. C

    Simple LC Oscillator

    As soon as you attach the two wires and try to read the frequency, you will load the circuit and it will stop working and you will get NO OUTPUT.
  9. C

    RFID Tag Detector

    The distance depends on the power of the transmitter. Elektor had an article on this.
  10. C

    Running high current electric solenoid using a H-bridge

    To get half-shift, the item you are operating must stay in the designated position AFTER the current is removed. You will need a micro switch in the mid-position to provide feedback as the energy (strength) to achieve mid-position will vary from day to day. You can also consider 2 cheaper...
  11. C

    ultrasonic sensor at 40 KHz

    I don't know what you are talking about.
  12. C

    Running high current electric solenoid using a H-bridge

    The plunger or core has to be a magnet to reverse the direction of travel.
  13. C

    Pickit 2 - won't write.

    Sometimes the chips will not program. I have a second clone and it works with all those chips that fail to program with a PICkit-2 That's why I use the clone all the time, now.
  14. C

    ultrasonic sensor at 40 KHz

    Why?
  15. C

    ultrasonic sensor at 40 KHz

    What gain are you getting. Increase the 48k to 470k and 18k to 220k
  16. C

    Need advise on charging Li-Ion battery

    You can really only charge 1 cell at a time. The charger only charges 1 cell at a time. You will have to add a switch to separate the parallel cells.
  17. C

    PCB Trace thickness/width

    Use 40thou and if it gets hot, solder tinned copper wire to the top.
  18. C

    LED flashlights

    Th problem is the circuit is designed for 4.5v and using 7.4v will be very inefficient as the difference between 4.5v and 7.4v will just be wasted. You will need to add an extra resistor.
  19. C

    Should I design my PSU for 230Vac/+-10%?

    You don't have to pay VAT. You don't have to pay any taxes AT ALL. Tax is voluntary.
  20. C

    Please help me with a simple circuit

    Do you have electrical igniters ?
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