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  1. Chemelec

    Help with PIR

    First you should have traced out the circuit and created a Schematic. Than it would be easy to determine the changes that are needed.
  2. Chemelec

    Help finding a suitable transformer

    There is a Good Transformer Manufacturer in Canada. I have ordered a few Custom made transformer from them in the past. But Never that BIG. Hammond Transformers of Canada. I Phoned them and Yes they can make you a Custom Transformer with those specifications. Their Website is...
  3. Chemelec

    Help finding a suitable transformer

    Not knowing what is available in the UK, But you need to find a Transformer Manufacturer, And get one CUSTOM BUILT.
  4. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    Sunnysky: Just for curiosity, I hooked up a Blue, 20 mA LED with a 510 Ohm resistor and a 12 Volt supply. Forward biased, it lit up as expected. When I Reverse biased it, obviously it didn't light. Than I Increased the supply to 25 volts and left it connected for a full minute. (Reverse Current...
  5. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    STEVE: I Never Suggested to connect it Backwards. I Suggested that he "May have Put it in Backwards", so try reversing it. And According to his Reply, he was getting the Same reading, Both ways. Just sounds like a Bad LED.
  6. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    Sorry, Yes 12 Volts. The Circuit is TOO SIMPLE to be anything else, Other than a BAD LED.
  7. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    With the Resistor and LED Connected, Does your 9 Volts REALLY READ 9 VOLTS? If YES, Than I Suspect a BAD LED.
  8. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    LED Probably in Backwards.
  9. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    Possibly your Battery is Bad. Or you connected the LED up BACKWARDS
  10. Chemelec

    12VDC to 3.3VDC LED Metered after resistor

    If the Circuit is OPEN, There is NO Voltage Drop. Connect the LED, than measure the Voltage Across the LED
  11. Chemelec

    Small, common transformers

    Transformers are ONLY AC Devices. A Transformer that Outputs DC is because it has Rectifiers on it Output to Convert it to DC.
  12. Chemelec

    1st Buck Converter Design Help/Advice

    If you want to Buy that IC, Go to: http://www.findchips.com/ Put in the Part Number: TPS5403 And you will find that Digikey has it.
  13. Chemelec

    JEYTECH DSO138 oscilloscope worth getting?

    Some Metal Detectors circuits, Most Radio Frequency Circuits, and Many other circuits also. I have a 20Mhz scope and often wish I had a 200Mhz Scope. But if the 200Khz does what you need, than buy it. At least the PRICE is GOOD.
  14. Chemelec

    JEYTECH DSO138 oscilloscope worth getting?

    I have never owned a Digital Scope, Only Analogue one scopes. But that 0 - 200khz is Not very good.
  15. Chemelec

    Transformers

    Yes, as long as the input voltage is suitable for that particular winding. If you Exceed the proper input voltage for the winding, the transformer will overheat and eventually be damaged.
  16. Chemelec

    Transformers

    Dave, He wants AM.
  17. Chemelec

    Interfacing with old phone mic/speaker.

    Most of those OLD Telephone use a Carbon microphone element It contains carbon particles that get compressed with sounds, and than expand without sounds. This Compression and Expansion cause resistance changes to the applied DC Voltage.
  18. Chemelec

    Transformers

    This Circuit is from an OLD, "Popular Electronics" Magazine. L1 is a Standard, Adjustable AM Oscillator Coil. For Really SHORT DISTANCE Transmission, Do Not add the Antenna.
  19. Chemelec

    Transformers

    1m? 1 Meter or 1 Mile?
  20. Chemelec

    Transformers

    Bluepoint SEQ...........What are you trying to make? A transmitter? To transmit How Far? AM, FM, Short Wave? Want to discuss this by phone? The UK is a free call for me.
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