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  1. Arouse1973

    Need help building RF Detector

    For the minute if you have a phone that supports Android, have a look, someone might have done an application. If you want to build one it will need to be a high bandwidth version and we really need to know the frequency range. this can be from say 10Mhz to 8Ghz. I'll have a dig about.
  2. Arouse1973

    Need help building RF Detector

    Ok so what type of bug do you think it is? Microphone or camera.
  3. Arouse1973

    Simple circuit for Battery Status indication for 7.4v re-chargable battery?

    PMSL Adam
  4. Arouse1973

    Need help building RF Detector

    Get an RF scanner, you might be able to pick up something with this. Something like this might work. http://www.ebay.co.uk/itm/like/321247147866?hlpht=true&ops=true&viphx=1&lpid=95&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=95 Adam
  5. Arouse1973

    L.E.D battery capacity & charging indicator

    For batteries like Lithium it's very difficult during discharging because they keep a higher voltage right to the end and then just die. You would need a coulomb counter to get an accurate reading, but you would need to start off with a fully charged battery as Bob mentioned...
  6. Arouse1973

    RF audio receiver diversity circuit

    Ben Put this together for you, it should work ok if you keep the input between 200-400mV. Set the input for 300mV and the output should be 4V pk pk. So if your input goes up and down a bit it should be fairly constant. You should only see a variation of about 20mV on the output which has been...
  7. Arouse1973

    Simple circuit for Battery Status indication for 7.4v re-chargable battery?

    Hello. Umm could you be a bit more specific. If you want people to help you then you need to give us a bit more of a clue. Like battery type, voltage, Amp hour rating. What's with the weird typing? Adam
  8. Arouse1973

    RF audio receiver diversity circuit

    Hi Ben This is something like I was on about. You could try just joining the outputs together as shown with out the switching circuit. As long as their is no more than say 5 degrees phase shift between the two outputs it should work. You would also benefit from an AGC circuit. But I won't be...
  9. Arouse1973

    RF audio receiver diversity circuit

    When ever you express in terms of decibels it is useful to give the unit the ratio refers to. In this case it could be dBmV or dBV. I assume dBV because you give +/- 1V so this means the output level will be 10dBV smaller than 1V. That works out to be 0.31V, so also wondering how your going to...
  10. Arouse1973

    do i understand AC and DC current in a vehicle?

    Just my opinion in that solder joints can break easier than crimped joints due to the wicking of the solder up inside the wire which forms a stiff hard ridge. This is where the wire will break. This is one of the reasons the automotive industry use crimps. The other reason is ease of assembly /...
  11. Arouse1973

    RF audio receiver diversity circuit

    Hi Ben Can you explain in detail what the circuit is suppose to do. It's just I am not sure of the purpose of the caps on the input to the FETs it appears you are feeding them with a low or a high DC level. What's D1 doing across the outputs? Your circuit says +/- 1V, you won't get this...
  12. Arouse1973

    Protecting Fence Charger From Lightning

    Their are a few of ways lightning can damage equipment. Direct lightning stroke 1) cloud to ground or ground to cloud. Game over. Can be over 200,000 Amps.There is not much you can do about a direct lightning strike the cost would be prohibitive. Indirect lightning stroke 1)...
  13. Arouse1973

    Interfacing and controlling a high brightness LED to a microcontroller

    This might work, just put this together for you to have a look at. It is a constant current LED source. You may have to adjust the 4R for different currents. With the 4R and the other components it gives you 160mA. Make sure you drive the input with a nice fast rising edge and you might be...
  14. Arouse1973

    Power efficiency - many transformers, or one?

    Just thought I would mention that an standard ATX PC PSU shouldn't power up with nothing connected to the output. To enable it you have to connect the POWER ON (Green Wire)to 0V (Black wire). You could also use an LED on the power good (Grey wire) to indicate all the power rails are up to their...
  15. Arouse1973

    maximum current a resistor can take

    I think people might assume you know how to transpose formula. If you do ignore this. You need the formula from above P=I^2*R. You want I so you have to remove R and the^2 on I. To do this divide both sides of the equation by R which means R can disappear from along side I^2. This now...
  16. Arouse1973

    help ... confused not home work

    You can also use I^2*R if you don't know the voltage. Thanks Adam
  17. Arouse1973

    TDA2009 Bridge Amplifier Problem

    Can't see any connection issue. But what is the blue connection running between the amp? is this a wire link underneath the PCB or a PCB track? It looks quite long for the feedback connection. Adam
  18. Arouse1973

    Help with electric jewelry box latch

    Might help http://www.aliexpress.com/popular/power-lock-solenoid.html Adam
  19. Arouse1973

    Capacitor Capers

    Some things we consider 1) Tolerance of the capacitor value. 2) Capacitance variation versus temperature. 3) ESR (Lower is not always better) 4) Leakage current 5) Physical size 6) Robustness (Some are more fragile than others) 7) Working voltage 8) Ripple current 9) Dielectric...
  20. Arouse1973

    Infared Transmitter

    It would be nice if LEDs emitted light as a pure cone within their half power angle but they don't. They produce quite a bit of fuzz around the edges. To roughly work out the angle you need is you take the radiant flux of the LED divided by the solid angle of the cone which is...
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