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  1. duke37

    Transformer to build 12 volt battery charger

    I presume that you will need DC. If so why not get a simple battery charger? This will give you mains insulation, fuses, rectifier, ammeter and case. Cost will be similar.
  2. duke37

    transformer inductance 16000H??

    That looks right to me. Raven A simple transformer is relatively easy to understand but as soon as non linear effects or energy transfers are included, my mind boggles. Inductors can be used in so many ways.
  3. duke37

    How to not hear Mylie Cyrus when I am playing guitar?

    If you cannot get 1nF, you would be better to go up to say 10nF. I looked up Radio Shack USA and they have 1000pf 50V ceramic capacitors for $0.79 on line only. They do not recognise nF. In the UK such capacitors cost about 10p i.e. 10 to £1. The circuit you show has the 1000pF...
  4. duke37

    transformer inductance 16000H??

    You measured Xl NOT L as I pointed out in the first equation. Transposing the second equation (can you do this?) L = Xl/(2*pi*F) The 0.3A is the maximum current that the transformer can provide in the load without getting too hot or dropping too much voltage. It has nothing to do with...
  5. duke37

    transformer inductance 16000H??

    Not V = I * L but V = I * Xl Xl = 2*pi*F*L You are too high by a factor of about 300.
  6. duke37

    How to not hear Mylie Cyrus when I am playing guitar?

    You have a very generous father. The box does not need to be bigger than 1 x 1 x 1 inch, you can mount the two sockets on one side so that the connctions are short.
  7. duke37

    Discrete FET gate driver for LED driver

    There was a thread here studying the degradaton due to reverse e/b current. It is not a good thing. Spice does not seem to simulate this condition. Try a diode across the e/b junction.
  8. duke37

    Help needed (Solar Lamp Circuit)

    Ewe mutton ram the point home!
  9. duke37

    voltage multipliers?

    C component is a typing error, It should be DC, i.e.the alternating current should be passed by the capacitor and the direct component should be blocked. Harald has given several places to look up. For low voltages, there are chips which charge capacitors in parallel and then discharge them...
  10. duke37

    How to not hear Mylie Cyrus when I am playing guitar?

    Try a 1nF (1000pF) capacitor across the amp input to short out the spurious RF signal. Keep the lead lengths down.
  11. duke37

    Over-voltage & over-current Protection

    Please tell us how the circuit should work. As drawn, R1 and R2 just dump power. Is this what is wanted? It looks as if Qm is fighting the output of the op-amp. There is a connection between op-amp- and Qm base, both of these are inputs so where is the signal coming from?
  12. duke37

    two week lightbulb

    You could extend the time by only energising for a time after a movement. You could make a 'Jack-in-a-box'
  13. duke37

    Frequency Conversion

    Please give more details. Do you wish to give out an ultrasonic beep when any sound is input? Do you wish to preserve the amplitude and frequency information when shifted to 25kHz. A description of the reason behind this would help. Frequency shifts are the way superhet radio receivers...
  14. duke37

    How do you increase IR LED range?

    Freznel lenses are used to help drivers see round corners. Look at truck accessory suppliers, also e-bay and green energy firms. You will need a lens that passes the radiation that you wish to use. What do you mean by a globe and shotglass?
  15. duke37

    Help with simple project

    Many years ago in the UK cars were fitted with lights with two intensities. These caused accidents since the brake light was not noticed unless the change in brightness was seen. I suggest that you restrict your new lights to brake use only, separated from any tail lights. Do you have a...
  16. duke37

    Summing Amplifier Problem

    The basic inverting amplifier is also known as a virtual earth amplifier. The input terminals take negligible current so the current flowing through the input resistance is the same as that flowing through the output resistance. The voltage produced can be calculated by Ohms law. The advantage...
  17. duke37

    Quartz crystal help

    The change from 16mHz to 16Mhz changes an awful lot ! I do not know suppliers in the US.
  18. duke37

    How do you increase IR LED range?

    Have you heard of Google? A PCB is the least of the problems, you will need very accurate positioning of the components and a lens with very low attenuation.
  19. duke37

    Two 12v inputs switching

    Putting a diode in each supply line will stop any backfeed if the supplies are connected together. This will drop about a volt. You can connect your relays (with an extra contact) so that when the auxilliary relay is pulled in, the main relay is isolated.
  20. duke37

    Quartz crystal help

    That would need a big, big, big crystal. I suggest you make a 16MHz oscillator and divide by 10^9.
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