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    93C46 Programmer

    TheStigP11GT, If you are starting from scratch, it looks as if Mr. Lanconelli has an excellent set of tools. The hardware is almost trivial, and he has nice PC-based software already done for you. If you already have an Arduino and expertise in its use, it would not be a bad choice...
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    octal latch circuit problem

    Bruce, I realize that you are already in for a pound, but I have to say that this design is fairly crazy. The function can be realized with about half the parts, using no fragile ICs at all. Since the SCRs provide the latching function, there is no need for a separate octal latch...
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    Common Emitter Transistor

    vick5821, Each LM324 package contains four independent op-amps. These can be used as comparators, but are optimized for the op-amp role. They are stable with 100% negative feedback. Your circuit could be built with actual comparators, such as those found in the LM339. Note that many...
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    8550\8050 v's 2N3904/2N3906

    > Aye, the speaker goes to GND & SP, each of which are in series with the 100uF caps. I'm looking at this: http://www.2ne1.com/index.php/diy-hacks/drawdio// No. The SP connection is in series with a 100uF cap. Ground connects directly to the 555 pins, etc. Not in series with any...
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    8550\8050 v's 2N3904/2N3906

    BanksySan, You can try connecting pin 3 of the 555 directly to the speaker. The circuit will draw more current from the battery that way. I'm not sure what you mean by "two capacitors". Only the single 10uF capacitor has to do with the speaker in the circuit of your early post. You...
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    8550\8050 v's 2N3904/2N3906

    BanksySan, Thanks for posting the links. I haven't had time to make an exhaustive search through all the links, but we seem to have mostly photographs and videos, with few construction details. It is a bit hard to tell, but it appears that there are several designs. One uses a...
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    3 digit panel meter to read -volts

    Greatvalue1, Please do not become discouraged. It is possible to make this work. It may require quite a bit of patience, however. Your basic idea is sound. The problems are around the edges, rather than with the central idea. This thread has advanced several ideas that could help...
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    Common Emitter Transistor

    vick5821, There should be some fairly simple ways to improve your circuit. First, I think there's a typo in the connections between the output of U2A and the non-inverting input. There should be a resistor between these pins. The drawing seems to show a direct connection. The circuit...
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    8550\8050 v's 2N3904/2N3906

    BanksySan, The IC is an NE555. This part will not work at 1.5V. It is specified for a nominal 5V to 15V power supply. If you are working from some sort of existing design that used a 1.5V power supply, it is likely that a CMOS timer chip was used, rather than the NE555. Some CMOS...
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    blowing up capacitors

    CiaranM, gorgon may have spotted your problem. Do you have a voltmeter? Observe the voltage across the capacitor. See if it is anywhere near 45 volts. It would also be instructive to monitor the current through the cap, if you have a second meter. What kind of 9V batteries are you...
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    Seeking Advice for Buck Converters

    goodjboy, What sort of buck converters? Can you link us to schematics or descriptions? How big is the capacitor across the solar panel? How about any capacitors that might be part of the buck converters? What are you doing to ration power, when the loads would exceed the solar...
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    How to amplify a square wave cheaply?

    plukens, Thanks for answering my questions. Sounds as if you really want a box that plugs in the wall for power, and has connectors for in and out cables, rather than a construction project. Nothing comes to mind immediately, in the way of inexpensive off the shelf hardware. I'm...
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    How to amplify a square wave cheaply?

    plukens, Can you give us some more information? What is the impedance of your piezo disk? ( Often these look mostly like a capacitance.) Is your 50 or 100 volt figure average, or peak to peak? How fast a risetime do you require? Will the piezo disc tolerate a DC component on...
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    Question about RF coil

    dimkasmir, The short answer to your question is no. The coil from Fry's will not work. The Fry's coil has far too little inductance, and lacks a primary winding. Unfortunately, the Tubes and More website has just changed; last night the specified coil could be found, today it...
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    Common group problem and seperate supply

    vick5821, Here are some thoughts and questions for you. What sort of problems have you experienced? How many of these things are you making? How much current does your fan draw? At 12V? At 9V? Must the fan have as much as 12V for the higher speed; would 10V or so be enough...
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    Conversion from [-10,10]V to [0,5]V range

    cphus, Where is the AD628? All I see is a TL082. The TL082 is not a very good choice because it is meant for higher supply voltages than 5V. If you have 30V, or even 24V total, it will work much better. The TL082 outputs cannot drive a load close to the supply rails. Look for a...
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    Help with instrumentation amplifier set-up

    leeb_965, I believe that you have a very conventional instrumentation amp circuit; it should work OK, within its limitations. For production use, a single integrated part usually costs less at any chosen performance level, but it is no sin to make your own using op-amps. Any...
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    LM 35

    vick5821, The LM35 is an analog part. It does not require any microcontroller. Have you looked at the data sheet? http://www.datasheetarchive.com/dl/Datasheets-22/DSA-423890.pdf "The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly...
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    Driving primary isolated mosfets

    boots_n_braces, You need to find some design examples. I would look on the IR website for ap notes. I think Power Integrations, ON and TI also might be good places to look, as well as Fairchild. Have you been looking at SMPS controller ICs? The data sheets for these often have...
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    Power handling limits of resistors

    tonebrulee, Note that each resistor's power is generally rated with the resistor mounted to something that will draw heat from the resistor, not another hot resistor. If you just twist together the leads of several small resistors, then run them at maximum power, they may overheat...
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