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  1. Hero999

    negative ioniser

    The same basic blocking oscillator circuit, normally used to drive a flyback transformer, can also drive a centre tapped or dual primary mains transformer. Here's an example of a capacitor charger using a mains transformer with a centre tapped primary. It should be able to drive a voltage...
  2. Hero999

    Common Emitter Audio Amplifier Question

    The amplifier has too higher output impedance to power a 4R speaker. You need a power amplifier. The circuit you've posted is for a signal amplifier.
  3. Hero999

    How to amplify a square wave cheaply at 100 Hz?

    The piezo needs to be driven by a 100Hz square wave. How can a voltage multiplier circuit (which will convert this to DC) possibly work? If the signal generator had enough current capability (it doesn't) a simple step-up transformer would work but that's not an option here. An amplifier is...
  4. Hero999

    How to amplify a square wave cheaply at 100 Hz?

    Kevin, A voltage multiplier converts AC to DC so isn't an option and the rest of your post doesn't make any sense. plukins, An audio amplifier may oscillate, as it won't be designed to drive a capacitive load. Are you looking to build this yourself or buy off the shelf?
  5. Hero999

    c828 transistor

    I was going to split the thread but his post is on topic so it doesn't matter. You may get more help if you post the schematic.
  6. Hero999

    James Bond CIA Gadget Challenge

    I think he is probably right, a pen is too small. If there was a way it'd be only be able to be used once after each charge. There are other things to consider such as, in order to kill, the electricity ideally needs to pass through the heart and a pen is too small for the electrode spacing to...
  7. Hero999

    Dell 1901FP LCD Service Manual?

    I think it's a spammer. I deleted the post but undeleted it as it's vaguely on topic. I doubt it'll give you a better link.
  8. Hero999

    Capacitor Question

    The only dumb thing about this question is not enough information is given to answer it. Whether a capacitive discharge is fatal or not depends on many factors, including the person being shocked. A tiny static shock may be enough to trigger a heart attack in very vulnerable person yet many...
  9. Hero999

    Increase Current Output

    Because the components and PCB tracks are only rated to pass a maximum current of 400mA. If you try to draw any more, there's a risk it could overheat or some protection circuitry will kick in (the latter is more likely) and reduce the output voltage, therefore the current (Ohm's law). To...
  10. Hero999

    Increase Current Output

    The short answer is no, you need to buy a power supply with a higher current capability.
  11. Hero999

    Custom Headset Adapter

    You forgot to attach the photos.
  12. Hero999

    Buck converter for wind turbine

    Thanks for posting your project. I think the best solution for the inductor is winding your own. A ferrite core designed for use in an SMPS would be ideal.
  13. Hero999

    +5V and -5V OUT PSU Problem !!!!

    All right, you're not trying to do what I thought which was measuring its own power supply. The first thing which could be wrong is the 7660 isn't needed, as you already have a negative supply, so it needs removing. Secondly, what's the transformer's voltage rating? The filter capacitor values...
  14. Hero999

    Impedance relation between 2 Bjts

    Where's the schematic? Please stop asking questions without one.
  15. Hero999

    +5V and -5V OUT PSU Problem !!!!

    How are we supposed to help without a schematic? I did a quick Google for the typical configuration for the said IC and assuming you're using the standard set-up I don't know why you're surprised, you're short circuiting the power supply.
  16. Hero999

    Limit resistor heat dissipation by using LEDs in series?

    Yes, why not? The only thin you need to beware of is the minimum operating voltage will now be 6V, rather than 2V  but it will definitely last for longer.
  17. Hero999

    taxi meter using PIC16f84

    Sorry, no ones going to do your project for you. This is not a free electronic design service, I apologise if that's not clear. Electronics Lab is a forum where people help each other with their projects. If you want someone to design your project for you, they'll more than likely charge you a...
  18. Hero999

    taxi meter using PIC16f84

    Where's the schematic and code?
  19. Hero999

    Ground for LVDS signals

    A twisted pair will do but for optimum noise immunity, you need a screened cable.
  20. Hero999

    exposing the pcb

    The chemical used to develop PCBs is NaOH. It doesn't need to be a strong solution, 0.6% will do. The substance used to coat the board before exposure to UV is known as a photresist. Many different chemicals are used, each having different properties, see Wikipedia for more information...
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