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MP

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Posts posted by MP

  3. control a switch over the internet

    in Electronics chit chat

    Posted

    JamesTh777:
    Just a comment here about your tag line. I think that if all of the Christians could agree not to plug Christ and all the Muslims would agree to not plug Allah, as well as the Krishnas, Buddhists, etc. also holding back their views on life, then we could also expect the Satan worshippers to not plug satan on this site. Why open the door for religious wars on a site where everyone in the world is coming to share their experience in electronics? We all have different views on life. One thing we have in common here is electronics. I for one, really do not want to come here to see advertisements of any kind.
    Thanks for understanding.

    MP

  5. State Variable active filter

    in Theory articles

    Posted

    Designing your own filters requires a bit of calculation. You need to know what you expect for damping factor, Q, bandwidth, and gain as well as the center frequency. The standard State variable filter design uses 3 op-amps, which I think will give you an inverted output. If your design gives you an inverted output, all you have to do is add an op-amp buffer stage to change it. How much time do you have to learn this? You said you are trying to design one. What do you have so far?

    MP

  6. regulators

    in Theory articles

    Posted

    You would not refer to a regulator as a junction of two signals since the voltage at both sides of the regulator are from the same source. A junction would also imply the source comes from different directions, and the regulator is working with DC, which means direction of both sides of the regulator are the same. The output voltage of the regulator is the input voltage with a change made to it. I hope this explanation is helpful.

    MP

  7. IC question

    in Electronics chit chat

    Posted

    For some time I was making sure that I had the 4 corner pins for anchors and I left the other unneeded pads off my drawing as they were not needed. However, later I found that this was confusing to others as to which IC was there and left me the problem of making special parts drawings in the cad programs I used later on. Finally, I just left the package as is, drilled the holes and simply did not route the pads to anything as Billy has mentioned. Sometimes we make more work for ourselves in trying to eliminate some work.

    MP

  8. Free sample chips!

    in Electronics chit chat

    Posted

    I think that I should add:
    I am very grateful to these companies for providing samples for my prototyping purposes. We might rate them as fast or slow or grumble about package types available, but the bottom line is, they are free and an expense I do not have to provide to find out something is not what I want. I did not want my previous post(s) to seem like I was not appreciative of this service from them.

    MP

  12. LM317 Variable power supply

    in Projects Q/A

    Posted

    Hi Jandro,
    I have never seen anyone use this application. Perhaps the simplest way to do it would be to have the current change the intensity of light which activates a light sensitive resistor where the light sensitive resistor takes the place of the pot. You could make your own custom package if needed.
    I am sure there are many other ways to do it as well.

    MP

  17. Grounding circuit

    in General

    Posted

    As Mixos has said, you would only use earth ground or case ground when the circuit requires it. Some circuits depend upon a floating voltage and will not work when the common of the circuit is tied to earth ground. If you would like to post a particular circuit or link, everyone could comment further.

    MP

  20. Labeling the project box

    in Mechanical constructions/Hardware

    Posted

    Here is an update:
    VPC has it.
    From their description:
    ***3M discontinued Dynamark.***

    Quick-Mark

    Quick-Mark has replaced 3M's Dynamark as the preferred method for short run, rapid, in-house production of durable, self-adhesive signs, placards. Quick-Mark is UL approved and is used by NASA on the space station and shuttle.

    http://www.vpcinc.com/Products/dynamark.htm

    The down side of this is that they have increased the price from what I paid for it several years ago with 3M. Perhaps it is worth more, now that they use it in the space station and space shuttle. ::)

    MP

  22. 5 volt regulated power supply HELP!!!!

    in Electronic Projects Design/Ideas

    Posted

    I do not think this is what they were referring to. I think it is a question about the LMXX schematic.
    However, I have not seen very many tansformers with a secondary of 7 volts that have much current rating. If current is a consideration, then perhaps we should know the current needed of this circuit. If you need to limit yourself to no more than 5 volts such as used with microprocessors, then use the zener/resistor/caps schematic as is. If you need at least 5 volts, then yes, a 5.1 volt zener is better to use.
    Bogdan, why don't you also post your schematic with a transistor so that there is another choice?

    MP

  23. LM317 Variable power supply

    in Projects Q/A

    Posted

    They are test standards of the parameters used by the chip manufacturer. Your application might very well be different. If your application falls within the generic specs, then sure. If you are pushing the edge, then you have to look closer. You can still achieve the manufacturer's specs if you use proper designing techniques.

    For example, when a data sheet states that the device will work between -40C and +150C, they usually list a min max and typ to show their results. What they might not tell you is that 50% dropped out at +142C, and thus they can still compete with their competitors and advertise the +150C top end tolerance for temperature. But if you are manufacturing this device to be sent to the equator, you will want to provide more testing before you package it. This would be considered an extreme for any company. If you are using the device in your lab, you are pretty safe with the min tolerances given in the data sheet.

    So, in answer to your question, yes, you can rely on the specs. If your application is extreme, you might have to add something to the circuit to continue to achieve this.

    MP

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