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    Trigger an SCR to switch a negative voltage

    He is right, Rgk does affect holding current. I found these documents: http://www.littelfuse.com/data/en/Application_Notes/AN1001.pdf http://www.teccor.com/data/en/Application_Notes/AN1008.pdf http://us.st.com/stonline/products/literature/an/3563.pdf Especially the last one on page 7 has a...
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    Trigger an SCR to switch a negative voltage

    Last time, holding current is a fundamental and fixed as far as gate resistor is concerned characteristic of the SCR.
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    Trigger an SCR to switch a negative voltage

    So how does the quote from wikipedia relate to gate resistor Vs holding current? I think SCR is now synonymous to Thyristor, although they used to be slightly different things.
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    The use of solderless breadboards to teach son electronics

    You sound like a good dad. Your son seems to have the nack: Ok, maybe it is a good time to learn soldering then and implement some circuits on a matrix board. Before doing so you can try the circuit on a breadboard. In this way he will be introduced to 'prototyping'. There are abundant...
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    My ZVS Flyback Driver with pcb

    Post of picture of some sparks in the dark.
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    UJT

    Do people use UJTs any more? I think is an obsolete technology...Even in its time it looks like a purpose specific device. I had to read up on UJT operation, and I dont know exactly how R2 helps in temperature compensation. From the formula given here for R2...
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    The use of solderless breadboards to teach son electronics

    Hello, I believe that the first thing you have to aim for is enthusing / motivating your son and you in the subject. For this reason I would recommend more practical work than theory for starters. There are these kits that you can build 100s of circuits with. I grew up with this one...
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    Current Limiting Technique

    Also remember to record the state of the charge level of the battery as internal resistance will increase as the battery is drained.
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    Controlling IGBTs via a microcontroller

    No, it is not that simple. In fact, you could do a research degree on this. But some deviation from perfect is acceptable. I see the IGBT you are using is a power device. Generally, driving an IGBT is like driving a MOSFET. In you case is a big MOSFET with 1.56nF of gate capacitance. Do a...
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    ethernet portal circuit

    Hello, I avoided calling it a star ground as this is not for ground. It is like a 'star ground'. Google that. The idea is that all subcircuits that draw a small amount of current are not affected by the circuits that draw large currents. If they were sharing the same connection (not star), then...
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    ethernet portal circuit

    The idea with this IC is to use one decoupling capacitor per VDD line and then connect them all together to VDD using a star connection.
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    ethernet portal circuit

    If you are into software, consider an RJ45 module with built in magnetics, MAC/PHY and ARM microcontroller. Alternatively, the circuit that you have been putting together can be bought ready made here: http://uk.farnell.com/microchip/ac164123/board-pictail-plus-ethernet/dp/1439831
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    ethernet portal circuit

    That is in the Microchip datasheet for that MAC/PHY chip with SPI interface. Winding your own transformers for Ethernet is silly. Wurth Electronic (Midcom), Coilcraft and many others have hundrends of standard models to suit ANY application and wiring layout. Good luck with the TCP/IP stack.
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    GATEWAY NOTEBOOK POWER QUESTION

    Hello Mark. Please do not interfere with the battery in any way at this stage. Remove the battery and take the laptop apart. Locate the damaged PCB and take a good quality picture of it (<3000kB) and post it here. We will have a look at the board and tell you what to do.
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    50V, 50A H-Bridge IC needed

    I just had a better look at the final circuit. The zener voltage is too low which makes me think that you are operating them far away from the zener region. As suggested, reduce R2,R4. You can also measure and include in your resistor calculation the C-E saturation voltage of Q1, Q2 although...
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    50V, 50A H-Bridge IC needed

    If everything is fine and the heating is purely due to the Mosfet being a P-type, I can reccomend an excellent 8-pin IC to drive an N-channel device on the high-side by using a capacitor charge pump topology and an internal oscillator, gate driver.
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    HELP> AC Circuits projects

    Murderer  ;)
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    50V, 50A H-Bridge IC needed

    Try including some dead-time between switching bridgeA and BridgeB ON.
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    digital image processing

    Go to your local bookshop and buy a book on digital image processing and digital signal processing. The best way I can think of.
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    GATEWAY NOTEBOOK POWER QUESTION

    I dont think that will work as the battery is not just a battery, it is a 'smart battery' with integrated safety interlocks and monitoring circuits. Your laptop expects to be able to communicate wth the circuits on the battery to turn ON. If you connect just the battery positive and negative...
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