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    help with 1st LED setup

    Look at the information on driving LEDs in series here. edit: after some quick calculations, assuming these LEDs are standard red ones with a voltage drop of ~2V and a current draw of 20mA, those resistors should be about 1K. You could run 2 470R resistors in series to get the right...
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    FM radio circuit question

    I got the last of the parts a few days ago, and assembled it on a breadboard. I think the capacitance caused by the strips is causing it to oscillate because the loudest sound coming out of the speaker is a "brbrbrbrbrbrbbrbrb" sound. Moving near the board causes the buzzing to change frequency...
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    Atari Punk Console propblems

    Also, next time you build a circuit, it's often a good idea to test it on a solderless breadboard, so you can be sure that the circuit design works and none of your components are faulty before you solder it. It's much harder to look for problems and fix them on a soldered PCB than it is on a...
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    Imp !!! - Help needed in Thesis

    I don't think they meant that the 5V battery must power the bulb, I think they meant that the 5V signal must turn a bulb on. You could use a relay, where the 5V signal from a microcontroller switches the 240V AC current.
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    FM Transmitter circuit help

    If you're happy using a trimmer, here's a 6.2-30pF variable capacitor, which should be good enough.
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    FM radio circuit question

    I know I should be using an antistatic wriststrap and grounding myself before touching a MOS device, try not to touch the leads and keep static sensitive stuff in some sort of conductive foam. Any big points I'm missing?
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    FM radio circuit question

    I actually ordered the part I posted just after I posted it because it said it was a good replacement for the 40673, and a quick look at the datasheet suggested that it would do the job, just like you said. Good find on the supplier of 40673s, though. If the MPF131 doesn't work for whatever...
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    FM radio circuit question

    I found this, and it looks like a good equivalent at a good price. If I find any other sources of similar parts, I'll give links in case it helps anyone else.
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    FM radio circuit question

    Hmm. It seems to be a reasonably good match, but it's not possible to use surface mount devices on a through hole circuit board, is it? The MOSFET is being used as a frequency mixer in the circuit, is a dual-gate MOSFET the only way to do frequency mixing? Would it be possible to modify the...
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    FM radio circuit question

    A bit of both. At my school we have a special semester subject where you get to choose a topic that interests you and work on it for the semester, and give a presentation about what you did, what problems you encountered and other exciting things like that. I chose to build a radio and research...
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    FM radio circuit question

    I think I'll give it a shot. I'll see if I can get all the parts, like you said and to make assembly easier I will use a circuit design program to make my own diagram with all the component values on it(his diagram has all the values on a seperate page.) If it doesn't work on the breadboard, I...
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    FM radio circuit question

    Looking at that thread, it doesn't seem like such a good suggestion. Apparently it's a pretty shoddy circuit and the guy who made the thread hasn't had much success(although the way he's not within 100km of an FM station probably didn't help...) After some more searching, I have found a...
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    FM radio circuit question

    For an electronics project, I have been looking to build an FM radio. I have been researching and have a reasonably good understanding of the principles behind it, and have found several circuit designs. At first I was researching superheterodyne receivers which seemed quite interesting but the...
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