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  1. C

    Hall effect part suggestions?

    Pull apart a computer fan and get the hall effect "switches"
  2. C

    Primer on Transformers needed

    "I rarely see side by side windings 95% are secondary on top of primary" Everything in Australia is on split bobbins to achieve the 5,000v isolation.
  3. C

    Primer on Transformers needed

    "yes that would be true, but as I stated, that's very rare for power transformers" I am sorry to say you are totally wrong. Most transformers are wound with the primary and secondary side-by-side so you can provide 5,000v isolation.
  4. C

    Primer on Transformers needed

    "This effectively is how easy the core will transport magnetic flux." "Not really in favour of that comment, Adam" The core does have an enormous effect when the windings are on different legs. The core also has an enormous effect when the secondary is not drawing current. The core is called a...
  5. C

    Motor Project

    All motors produce electrical noise and the frequency of the noise depends on the RPM. Use a simple PWM circuit to produce the RPM, pick off the noise across the brushes and feed it back to the micro to give you a readout on a 4 digit display. .
  6. C

    relay driver

    "Assuming 15mA, the base resistor should be about 20kΩ or less." The base resistor should be much less than 20k. Use 2k2 or less The transistor has a gain of only about 50 to 70 at 50mA. The transistor divides the 2k2 by 50 to get an equivalent of 44 ohms for the resistance of the...
  7. C

    Homemade 10 ohm resistor

    "People keep thinking little 9V batteries can power anything they want. " "A 9v battery has enough energy to start a car." This highlights the difference between ENERGY and POWER.
  8. C

    Homemade 10 ohm resistor

    "People keep thinking little 9V batteries can power anything they want. " A 9v battery has enough energy to start a car.
  9. C

    find faulty capacitor in circuit if there are many

    The first things to suspect are transistors, then IC's. I have repaired 45,000 products. Maybe one or two shorted tantalum capacitors in Blaupunkt TV's - but they are the last thing to suspect.
  10. C

    Door Monitor

    http://www.ebay.com/itm/IC2272-4-CH-Channel-Wireless-RF-Remote-Control-Transmitter-Receiver-Module-Board-/371018079020?pt=LH_DefaultDomain_0&hash=item5662669b2c
  11. C

    Door Monitor

    "As you're in the UK I would use easy radio." It is going to much easier to use 303MHz Tx/ Rx. It is only $4.00 and has everything finished and ready to interface. With 303Mhz the TX only takes 10mA for 300mS.
  12. C

    Door Monitor

    The receiver has 4 outputs. You will use 2 of these. You will have to make a PIC interface circuit that plugs into the USB socket and delivers the lock/unlock data to the log folder.
  13. C

    Door Monitor

    Use the change-over of the micro sw to generate a pulse for buttons A and B of a 303MHz Tx Rx
  14. C

    Door Monitor

    How are you going to detect is the door is locked or unlocked?
  15. C

    Door Monitor

    This requirement is more involved than you think.
  16. C

    Beginner question regarding battery charge and circuits

    "electronic components that are located in Area C " You only have to be careful of components located in area 51
  17. C

    Drive 12V 15A load with PWM 18V-48V 2A

    As soon as you provide PWM, you are taking away the ceramic heater feature and you might as well use a nichrome heater for $3.00. That's why it is POINTLESS.
  18. C

    Drive 12V 15A load with PWM 18V-48V 2A

    Let me take it further. If you put the heater in a box of asbestos, the heater will take a very high current and when it reaches its operating temperature the dissipation will be 21 watts. The amount of heat will heat up the asbestos and the temperature of the ceramic will get slightly hotter...
  19. C

    Drive 12V 15A load with PWM 18V-48V 2A

    No. You got it wrong. The ceramic heater heats up to a final temperature and releases it heat-energy to the surroundings and takes 21 watts. If you direct a fan onto the heater, the temperature of the element will drop slightly and the current will increase. If you blow harder, the...
  20. C

    Drive 12V 15A load with PWM 18V-48V 2A

    You have got a very nasty heating element that has an output of 21 watts but it will take a very high current during the time when it is heating-up. This heating element is only designed to be connected directly to a 12v car battery. You are wasting your time driving it in any other way.
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