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  1. L

    more help on h-bridge

    Am I the only one who disagrees with the layout of this H-bridge?
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    Turn the lamp On & Off gradually...

    I'd use a microcontroller with a TRIAC.  I'd have it periodically check the line frequency so that it could work in different regions (with different frequencies) and in areas with poor frequency regulation (or on a portable/emergency power generator). 
  3. L

    looking for 3.84 MHz crystals

    I've found a source for 3.875MHz, which is close enough for my purposes.  Thanks for reading my post.
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    Charging 39 NiMH cell battery pack

    Do you already have a 39 cell pack?  I wouldn't advise making a charger for it as the voltage dip for the first cell completing it's charge may be difficult to pick out of 50+ volts.
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    Need Ic which can Enable Its outputs One by One!

    With that requirement, you're not likely to find many chips that fit the bill.  You'll probably have to use an FPGA.
  6. L

    My girlfriend is getting into electronics

    Yes, I have.  She just might- she already overtook me in math 3 years ago.  Did I mention the holograms she made last quarter?
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    PIC or AVR?

    Do you have local friends who use microcontrollers?  if so, consider using what they use- they're a help resource.  What's easiest for you to get?  Choose one on price, convenience, support- they're about equally capable.  Both companies offer samples (last I checked Microchip had more devices...
  8. L

    My girlfriend is getting into electronics

    I've bored her to tears some time ago, but her major requires that she take some classes in electronics.
  9. L

    looking for 3.84 MHz crystals

    The distributors I've checked with don't keep these in stock.  I'm hoping to find someone who'll sell ten or twenty of them.
  10. L

    Can I run two regulator circuits off one transformer secondary?

    Ouch!  Those meters suffer from a design shortcut.  Neither input pin is common to either supply pin, and it may be difficult to stabilize if there is an external current path.  They're great for a battery powered panel meter, but inconvenient in some other applications. The current is a bit...
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    How do I start off for a Robot

    Have you seen office chairs that roll around?  The wheels can turn to roll any direction.  Those are casters. By dedicated device I mean something that will take your commands for what the motor is to do, then it will make the motor do it. To find which motor is suitable, you balance your...
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    How do I start off for a Robot

    Sumit, Most of the hobby robots I've seen are based on two drive wheels.  Some have three wheels (one caster), some have four wheels (two casters), some have tank treads (still same concept).  My first robot (I still haven't made one yet) will be this way too. It is true that you need to learn...
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    I2C terminal for PC

    I'm not getting anywhere fast with my postings elsewhere, So I'll paste it here. Some of the things I'd like to make will need I2C communication. I figured I'd have to make a terminal first, but that leaves the same problem- how to talk to it while debugging. I went looking for some...
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    Transformer VA ?

    Does the transformer have standard E-I laminations? If so then with the dimensions of one of the outer legs (cross-section) and the power frequency I can give you a guess as t o the total VA rating. If the outputs are the wire they're wound with (not terminated to a terminal strip or spliced...
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    read/write operations

    Good afternoon, Read-modify-write means that the port is read, the bit selected is set or cleared, and the result is written to the port. The disadvantage of this is that the output that is driven high by the output may be overloaded and read as low (or vice-versa) as the output latch is not...
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    "Desperate Housewife" with Remote Control Project

    What you want is a hobbyist with carpentry, mechanical, and electronic skills. Lo and behold! Here you are. You can probably get more informed suggestions if you can provide some pictures. If you have a web site of your own to post them on it would be easiest. Posting too many pictures here...
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    Making an electric furnace.

    An appliance repair shop may be willing to sell you an "infinite range control" for an electric stove. This is a self heating thermal switch which is rated for 240V and at least 10A, usually more. Run the elements in parallel if they are identical. What are you planning to use for a crucible...
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    connecting a sensor to a switch and LCD display

    The 16F59 is a fairly new product in the 12 bit core family. I would recommend getting the 16F877 for several reasons. Any issues are likely to be known and documented, more people are familiar with them, "projects' are designed around them, and they have features you will want that the '59...
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    connecting a sensor to a switch and LCD display

    The fewer communication protocols you have to deal with, the less code you will need to write. I would choose I2C because it allows several different devices to share the same communication bus- the first byte transmitted is an address header. The CO2 sensor does not have this, so it will have...
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    connecting a sensor to a switch and LCD display

    The part you are missing is a microcontroller. The CO2 sensor has two types of serial communication available, either of which can be used by just about any uC. The LCD module (you didn't say it was just a DVM) will need to have te information spoon-fed. You will probably want to have a...
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