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    RC Circuit (How?)

    Clarify what's happening here... in the first diagram, pin 4 is normally closed. In the second, it's normally open... You'll have to experiment to see what voltage your relay turns off at. I'm not sure how your second circuit is meant to work, but I can see the principle (using a capacitor to...
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    Reading Pulse signal from a flow meter

    There are a number of PCI and USB based dataloggers/oscilloscopes avaliable for the PC. Any number of these would work, but they're quite expensive and perhaps a bit over-the-top for pulse counting. Google "PC datalogger" or something like it.
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    Lets make our printer wireless !

    I have considered this in the past. Using IR is interesting, but probably quite complicated. To get full functionality, you'll need to buffer whatever data the computer sends, send it one bit at a time via IR, plus any status bits. You'll then need to re-compile those bits into a parallel stream...
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    Protecting the motor

    The device you use will be put in series with the motor. When the motor is stopped/stalled, the current through it will increase. So your polyswitch or current limiting circuitry will trip the circuit if the currnet rises too high.
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    free energy motor

    Anyone else reminded of "all your base are belong to us?" Sarcasm aside, I have not seen one overunity site that actually describes HOW the thing is meant to work. There are very vague allusions to bits of particle theory, mostly virtual particles that are somehow tapped by this carefully timed...
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    free energy motor

    So, if we accept the rather dubious premise of "phi-flux", how does the circuit harness this energy? You mention timing circuits, but it's all a bit vague. For instance, you say there is "no Lenz law". Normally all the components in the circuit you posted obey all Maxwells equations. What is...
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    Numeric counter displayed in 7-segment LED

    Those are the ICs you need, so it's just a matter of wiring them up correctly: http://www.aaroncake.net/circuits/counter.htm Make sure your seven segment display is a common anode type if you're using this circuit. If not, either find a common anode type, or swap the 7447 for a 4511
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    Help! Connecting power supply to small load/solenoid

    A solenoid is not really a "short circuit" in the normal sense of the word. If you drew out the wires in a solenoid or inductor, the behaviour would be of a normal piece of wire. The coiling up of the wires means that the coil creates a magnetic field inside it. This magnetic field in turn sets...
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    free energy motor

    So what is the motor powered by? What are the physical principles behind the motor turning? I think we're all a bit confused.
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    PCB Etching Tank - Do it yourself

    I already etch lots of one off boards, current process is printing onto tracing paper, UV exposure, develop and etch in a plastic tray. This would be fine if I didn't share a house with four other guys. If it could go a bit quicker and be a bit more "self-contained", I'd get in the way less...
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    PCB Etching Tank - Do it yourself

    I haven't actually bought anything yet, I'm collecting information. I'll only be etching one-off boards, so I won't have a lot of etchant to heat. I'm still not sure about this, you say: Well "top-of-the-scale" for the aquarium heaters I've seen is about 32C. Presumably you get your etchant...
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    PCB Etching Tank - Do it yourself

    OK, what sort of wattage heater should I be looking at then? It seems to be the case that a more powerful heater is meant to heat a larger volume of water (i.e. larger fish tank) to the same temperature (about 32C), rather than actually increase the temperature any further and kill your fish. I...
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    NEED HELP IN A BAD WAY.... LED PROJECT

    Hmmm... can't remember how I got round that... perhaps it wasn't an issue, not sure - it was a good few years ago! But there must be a way around that problem. The last 4017 output could be used to turn on a PNP transistor to switch the SCR power on. When that output goes high, the transistors...
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    PCB Etching Tank - Do it yourself

    I keep meaning to build myself an etch tank, but one thing eludes me: People use aquarium heaters to heat the etchant, but all the aquarium heaters I've seen have a built-in thermostat that keeps the water at a maximum of about 32C, about 10-15 degrees too cool. How do you get around this, or...
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    NEED HELP IN A BAD WAY.... LED PROJECT

    Sounds similar to a project I did for GCSE. I had the 555 clock a 4017 decade counter. Each output was connected to a thyristor that turned an LED on. Thus after 10 pulses, all the LEDs were on. It's not the ideal solution, because it requires 10 discrete thyristors, but it worked.
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    Fiber Optics

    What sort of project are you looking to do? Fibre optics is just a way of carrying information, so the possibilities are endless really. You could try and build something that transmits music from your stereo to another room in your house, for example. Or you could try and send information...
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    smps modification

    You might want to look at the "5v to 3.3v" thread near this one. Basically deals with the same problem, but you'll need to account for the increased current your converter will be carrying.
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    3 Legged 5600uf cap

    Type "three terminal capacitor" into Google and a lot of pages come up. Looks like they're designed to conteract the inductance of the leads to lower the ESR. Or something like that, I'm no engineer.  ::)
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    Mp3 Player

    There are interfaces for microcontrollers (via SPI, I2C) that will allow communication to/from USB devices or memory cards, but I'm not sure if they'll cope with the data rate needed to play MP3s. For instance...
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    Microphone Switch

    Most switches activated by sound that I've come across use a circuit similar to this one: http://www.fowkc.com/elec/clapper.shtml That's electrect mic --> amplifier --> input to logic / microcontroller. Mine works, but I'm sure it's not perfect.
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