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  1. Hero999

    switching speakers (4 conductors per) 10 + with IC's ???

    That's easy to get around: use an SSR made with two MOSFETs connected back to back rather than a TRIAC.
  2. Hero999

    switching speakers (4 conductors per) 10 + with IC's ???

    You haven't made your requirements clear, please post a schematic. Is the power or signal? CMOS switchs are lower power signal devices, only work with signals within the power supply rails and shouldn't be confused with solid state relays.
  3. Hero999

    timer to trigger latch

    You didn't help us to help you much in the first place by not making your requirements clear. In future, post drawing, schematics, graphs and charts and you'll get the answer you were looking for much more quickly. To be honest, I'm still not sure whether the circuit 'you've designed will meet...
  4. Hero999

    Help please about the very simple power failure light project

    My design has not been tested but it consists of sub-circuits which have been tried and tested. The mains transformer is just a standard 9V >100mA or >1.2VA unit. Just make sure it's reasonable quality and has short circuit protection or is fitted with a thermal fuse. If you're worried...
  5. Hero999

    Help please about the very simple power failure light project

    This is a totally silly idea. Why hash a dangerous transformerless power supply together with a 12V relay when it would be cheaper, safer and more reliable to use a relay with a 240VAC coil in the first place? 9V is too lower voltage to power three white LEDs connected in series properly. It...
  6. Hero999

    Stereo Power Supply Core Problem

    Does it vibrate and make a loud humming sound? It could be because you've not secured the laminations and the vibration increases the heating.
  7. Hero999

    timer to trigger latch

    Just looked at the last circuit with two transistors. Whn the power is applied C2 will charge causing the horrizontal transistor (I'll call it Q2) to turn on. The vertical transistor (I'll call it Q1) will then turn on  as C1 will charge. The relay will be activated shorting out C2. When C1 is...
  8. Hero999

    To Kindle or not to Kindle

    Never heard of it so used Google. If you buy it, I'd recommend you don't buy any ebooks from Amazon as they can delet them whenever they want.
  9. Hero999

    timer to trigger latch

    Threads merged. Don't create multiple topics about the same subject - it wastes our time and yours. We still don't know what you want. An electromagnet is inductive not capacitive. You've posted a coupled of standard 555 timer schematics, not your problem.
  10. Hero999

    timer to trigger latch

    Why? What are you trying to do? Your discription is very vague. The current though a relay's contacts will depend on the load. Or are you saying you need a current to activate the relay, i.e. when the curerent exceetds 10mA, it turns on? You'll also recieve more help if you post a schematic.
  11. Hero999

    dc.dc voltage booster circuit-please help

    It's not possible for both the output voltage and current to be constant, either one or the other will vary as the load impedance changes. Even specifying a power supply requires some electronics knowledge, let alone designing one. I think you need to do more research and aquire the knowledge...
  12. Hero999

    Audio Video Battery question

    Have you tried filtering the power supply to each of the devices? Try adding ferrite beads and ceramic capacitors. I still wouldn't rule out a grounding problem. If so using an isolated DC-DC converter for two of the devices should solve the problem. Have you tried running the preamplifier...
  13. Hero999

    40 VAC to energize 24 VAC relay coil?

    No one makes 1.22W resistors, it's common practise to just use the next power rating up.
  14. Hero999

    40 VAC to energize 24 VAC relay coil?

    That sounds about right to me. I calculated 349R, the nearest standard E24 value is 360R but any value between 330R and 390R will do. I = P/V = 1.1/24  = 45.83mA R = (Vin-Vout)/I = (40-24)/0.04583 = 349R Your power calculation doesn't look right to me but fortunately your result was...
  15. Hero999

    40 VAC to energize 24 VAC relay coil?

    Yes, put a resistor in series with it. Measure the current in the coil and calculate the required resistance using Ohm's law. Hint: it's the same formula as that used to calculate the series resistor for an LED (this can be found using Google) but replace the forward voltage with 24V.
  16. Hero999

    POWERING LEDS FROM CAR POWER SUPPLY

    Those are both constant current sources so would work but they're step down converters, which means the output voltage will always be below the input. The LEDs will need to be connected in parallel as strings of two. Because LEDs don't current share well you should include current balancing...
  17. Hero999

    Solenoid driver circuit

    LTSpice, as I said above.
  18. Hero999

    POWERING LEDS FROM CAR POWER SUPPLY

    That's not true, LEDs ideally need a constant current source. The inefficiency of powering LEDs from a car battery via a resistor is the power lost in the resistor. The varying voltage just means the brightness won't be constant. The best and most efficient way is to use a switched mode constant...
  19. Hero999

    Beats by Dr. Dre Headphones

    And then the rest should be obvious. Think about it, you don't need any knowledge of electronics to know the answer.
  20. Hero999

    Where to find solder tips

    Ideally as high as possible but there comes a point when the element is too big. I'd say 50W is good for a general purpose iron.
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