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  1. Hero999

    UnFETtered Crystal Radio

    You mean the project linked below? http://www.electronics-lab.com/projects/rf/011/index.html I wasted my time reading the whole thing and it provided no explanation of how it actually works. The author says it doesn't use diode rectification which I how I would thing it would work. He also...
  2. Hero999

    Automatic Fan Controller - Help (w/ relay?) Please!

    It sounds like you've found the problem. The coil voltage is the required voltage, not the maximum, the contact voltage is a maximum voltage rating. Actually I'd expect the coil to activate the relay at around 18V to 20V and will be able to safely tollerate 28V to 30V. You need a relay with a...
  3. Hero999

    LM338 Power Suply Current Regulator

    When the current is below the current limit , the voltage across the first LM338 (used as a current limiter) will be very low: between 1.5V and 3V, depending on the current drawn and IC temperature so the power dissipation will be 15W maximum. When the current exceeds the limit set, the voltage...
  4. Hero999

    hydroxy gas power supply/separating oxygen and hydrogen from water

    Then you obviously measured current in the correct manner by connecting the meter in series with the circuit.
  5. Hero999

    hydroxy gas power supply/separating oxygen and hydrogen from water

    If the short circuit current is only 9A then the batteries are flat and dead. I looked up the datasheet for one of the batteries you're using. It's 7.2Ah and the internal resistance is just 40mΩ when in good condition and fully charged. When fully charged to 13.8V, the short circuit current...
  6. Hero999

    TDA7240 distortion at low volumes

    No, copy and paste the link from the page, not the quoted post. He made a mistake with the url tags which can be used to create links that appear as descriptions rather than a long website address. For example, click here to Google for BB URL tags.
  7. Hero999

    TDA7240 distortion at low volumes

    It could be crossover distortion which is more noticeable at lower volumes. The link works if you copy and paste it into the browser's address bar. The schematic is simply copied off the datasheet.
  8. Hero999

    LM338 Power Suply Current Regulator

    The LM338 will only overheat after the current limit has kicked in, before then the voltage across it will be between 1.5V and 3V, depending on the current and ambient temperature. When the current limit, the current regulator might shut down, depending on the load voltage and current setting...
  9. Hero999

    Power Supply for capacitor bank

    Yes, the 555 generates when operating in astable mode. The inductor needs to be pulsed on and off to generate high voltage pulses for the back EMF to be generated. The frequency will depend on the current, the inductance and input and output voltages. You should not think of the frequency but...
  10. Hero999

    LM338 Power Suply Current Regulator

    The circuit is totally impractical. Where are you going to buy a 12 Ohm pot. rated to 5A or 6.25W when it's set to 0.25Ω? The maximum power rating for a pot. is always for the full track so when the wiper is in the middle it's halved, in this case 0.25Ω is just under 2% of the maximum...
  11. Hero999

    Power Supply for capacitor bank

    I've given you enough information to answer that yourself.
  12. Hero999

    Class D amplifier (different kind :)

    I can buy a single TL082 and a single LM393 for 53p and 28p respectively from RS. Components here aren't expensive, unless you shop at Maplins. http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0304217...
  13. Hero999

    Power Supply for capacitor bank

    If it's constant current then the voltage ramps up linearly. A 970
  14. Hero999

    To build a transformer

    Strictly speaking a transformer is AC not DC, you need a transformer followed by a rectifier and capacitor to get a DC voltage. Just because the power brick or steering wheel might be specified at 900mA, it doesn't mean the current needs to be limited to that, it's just the maximum current. To...
  15. Hero999

    Class D amplifier (different kind :)

    You're lucky to get 60kHz from an LM1458, the LM324 is even slower - look at the datasheet. Please post the schematic of the triangle wave generator. I think you need two op-amps and two comparators. An op-amp is a very poor comparator, you'll need one with a huge slew rate and a massive...
  16. Hero999

    TT2076

    Use Google translate. http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.ges.cz%2Fsheets%2Ft%2Ftt2076.pdf&sl=auto&tl=en
  17. Hero999

    DESIGNING A SUPERCAPACITOR CIRCUIT

    Hee needa a 1000V capacitor which would mean putting 200 5.5V capacitors in series. The most efficient way is to use a switching regulator which I'd say is the only choice if you want it to last for as long as possible. Usign a lower is much more sensible as it's safer and can be more easily...
  18. Hero999

    Power Supply for capacitor bank

    Look it up on Wikipedia. A 555 is not a regulator, it's an oscillator, you could use any IC which can be configured as an oscillator and will work up to the required frequency. The  op-amp is the part which performs rough regulation by disabling the 555 oscillator when the voltage is too high.
  19. Hero999

    Capacitor Voltage

    No. Yes, to an extent but that's only because it's less important to have close tolerance of large capacitors, making it an unnecessary expense. The type of capcitor makes more of a difference to the tolerance, for example large power factor correction capacitors, with values as high as 500V 100
  20. Hero999

    Filters

    Filters are generally composed of capacitors, inductors and resistors so your qestion doesn't make any sense. Do you mean active filters? Yes, active filters do have the advantages of bbeing able to drive low impedance loads and have amplification whic passive filters do not.
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