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Posts posted by MP

  1. You will probably find that the 0.8mm bit becomes your most used size. Are you using a small drill press or drilling by hand? The smaller drill bits tend to break very easy. You will find opinions differ in this subject, too. Rule of thumb is that you want to have the least number of different sizes per board so that you are not having to change the bits often. Thus you might use a different size for a particular component from one board to the other. The rules are pretty flexible for hobbyist use. In the circuit board industry, the board layout person decides which sizes are used. This is given to the board house in a NC drill file. The sizes are usually already determined inside the board layout program when you choose a part from the library. If your board layout program generates NC drill files or Excellon files, it also makes what is called a tool file. This tool file lists the sizes that you are expected to use. This comes from the part package in the board layout program's library.
    If you want to get as close as possible to the actual diameter of the leads on the part, you can look at the data sheet and plan to drill the hole just slightly larger than this. However, a tight fit is not necessary.
    We use numerical sizes where I live. My most used size is a #70 or (.028"). This for ICs and common components such as resistors and caps.
    I hope this is somewhat helpful. ;D


  2. Absolutely no offense taken here. I just felt the need to point out the reasons for the other methods. I am also glad that this method works well for you. There are lots of projects on the web which also provide a board layout. In the past, this has been a very expensive undertaking for the hobbyist. It is good to see alternatives to sending them to the expensive board house. :D
    Happy etching!

  3. Billy,
    There are many ways to make PCBs and these are as different as using any one of the many circuit layout programs. Some of it has to do with taste, but a lot of it has to do with features. The same is with the many methods of fabricating PCBs. In my workshop, the transfer method will not give me the resolution that I must have. I use the photographic method. The magazine method will work for most hobbyist projects. But do not laugh at those who find they need a different method. ;)


  4. The CXA1110AS/B is an obsolete chip. Last buy date, according to Sony, was 12/97. The best two choices might be:
    (1) Contact Sony on their website and ask for an alternate
    (2) Search the obsolete parts vendors to see if they have some available.

    The following link has a list of obsolete parts and sales contact that can help you. It is a long link. Be sure to fit it all in the browser.



  5. Hello HA,
    I have found the following link at ST Electronics.


    It is the press release for the STi5518. This is a pretty interesting chip with a lot of features. If you do not find the data you need from this link, they have a contact link on this page. You can request the data sheet directly.
    It would be interesting to hear about your project when you have time to share. ;D


  6. This is a bipolar stepper. This actually has wires to each of the coil ends in your motor. If you have a diagram of your stepper, you will see 4 coils in sets of two. A 6 wire stepper simply has these connected together inside the motor. You will connect the 2 wires at the center of the 2 coil set together, changing it from a 8 wire stepper to a 6 wire stepper motor. Perhaps I have not explained it well. If you still do not understand, I will find some diagrams and post them.

  7. How real it is to power this much from a solar panel is dependent solely upon
    (1) how many panels you have (Panels are usually rated by Watt)
    (2) how much backup power you have (batteries)
    (3) how much sun is in the region you live in. (closer to the equator is better)

    #3 is the biggest problem in most cases and many system designs will add a safety factor such as added wind generator for those occasions when the sun is not out. These also seem to be the best days to count on the wind to blow.


  8. Kasamiko,
    Some information on Inverters:
    There are 3 major types of inverters - sine wave (or "true" sine wave), modified sine wave (actually a modified square wave), and square wave.

    Sine Wave
    A sine wave is what you get from your local utility company and (usually) from a generator. This is because it is generated by rotating AC machinery and sine waves are a natural product of rotating AC machinery. The major advantage of a sine wave inverter is that all of the equipment which is sold on the market is designed for a sine wave. This guarantees that the equipment will work to its full specifications.
    Some appliances, such as motors and microwave ovens will only produce full output with sine wave power.
    A few appliances, such as bread makers, light dimmers, and some battery chargers require a sine wave to work at all.
    Sine wave inverters are always more expensive - from 2 to 3 times as much.

    Modified Sine Wave (quasi-sine)
    A modified sine wave inverter actually has a waveform more like a square wave, but with an extra step or so. A modified sine wave inverter will work fine with most equipment, although the efficiency or power will be reduced with some. Motors, such as refrigerator motor, pumps, fans etc will use more power from the inverter due to lower efficiency. Most motors will use about 20% more power. This is because a fair percentage of a modified sine wave is higher frequencies - that is, not 60 Hz (or 50 Hz, depending upon your location) - so the motors cannot use it.
    Some fluorescent lights will not operate quite as bright, and some may buzz or make annoying humming noises.
    Appliances with electronic timers and/or digital clocks will often not operate correctly. Many appliances get their timing from the line power - basically, they take the 50/60 Hz (cycles per second) and divide it down to 1 per second or whatever is needed. Because the modified sine wave is noisier and rougher than a pure sine wave, clocks and timers may run faster or not work at all. They also have some parts of the wave that are not 50/60 Hz, which can make clocks run fast.
    Items such as bread makers and light dimmers may not work at all - in many cases appliances that use electronic temperature controls will not control. The most common is on such things as variable speed drills will only have two speeds - on and off.

    Square Wave
    Very few but the very cheapest inverters any more are square wave. A square wave inverter will run simple things like tools with universal motors with no problem - but not much else. These are seldom seen any more except in the very cheap or very old ones.


  9. Thanks Staigen. Since I like to make my own PCBs for small jobs and shop around for larger ones, ExpressPCB would be inhibitive for me. I did try it at one point but did not care for the lack of gerber output. Their prices for boards are not bad, I just worry that at some date in the future I would find a better deal on boards and be faced with laying out my boards again in another program. All other board manufacturers accept the gerber output. I am not sure if anyone else accepts the ExpressPCB files.

  10. I find that I use a number of different programs for creating schematics and board layout. The different programs all have their features and also some dislikes. If I want a small simple board, for example, it is not always easy or quick to do in OrCad or Eagle. In such a case, I just use a point to point drawing circuit board program like the old PC Boards package for DOS.
    I have never tried ExpressSCH. Is there a link to a demo version?

  11. There are two different methods used for this. One is a simple metal detector. This is what is used for finding buried cables before digging. You do not have to have a power source in the cable to find it. The other type is an inductive pick up which pulses an amplified votage, then is sent to either an audible source or a visual one. This type of circuit also does not require you to send a signal through it as it is used to sense a signal that is already there. I do not have a metal detector schematic handy, but I am sure they are all over the web. I do have an AC Wire locator schematic, which I have attached. For the coil in this circuit, you can use the type that has a suction cup and attaches to a telephone. These are common in the phone bug projects. This might not be exactly what you are looking for, but might give you a start and hopefully some ideas on making your device.



  12. There are a number of ways to do this. What you are looking for is automatic switching. This can be accomplished with transistors and comparators. If you are familiar with comparators, you can use them to switch the base of a transistor that is rated for what you are going to run through them. You would tune the comparator to the trigger voltage. A twist on this would be to use a relay instead of the transistor. Many relays are buikt with a normally open and normally closed channel, so you could get a dual purpose out of one device. With this, you could switch one signal on and the other off at the same time. Are you familiar with microcontrollers? You could build a voltage divider connected to the DAC on a microcontroller, then write the code to send a signal to a particular output pin when the reading is greater than X volts. The voltage divider is to protect the microcontroller because it cannot handle more than 5 VDC. This output pin would then switch on the transistor or relay. At the same time, you could have another pin switch off the other transistor, etc.


  13. Sounds like an interesting project. What are you making? there are a number of alternatives to battery. One option is what is known as super caps, which is what is used in many computer systems. Once they are charged they will hold a charge for a very long time and thus are used in the place of batteries in many applications. One thing you did not state is how much voltage and how much current you will need. Another alternative is solar power. Of course you either need the storage device or only use the device when there is sun. Next, there is radio waves. I think this is closer to what you are wanting. Any time you capture an RF signal, you have a voltage. It is not very large, but you can actually make a power supply from a simple radio receiver circuit.

  14. I am assuming that there is a low power side to this circuit. The electric fence amplifier box is stepping a smaller voltage up to this level. Why not use a voltage divider on the low voltage side to bring it down to 2 V or thereabouts and run that through a resistor to the LED? It will be much less expensive for parts to step up than to step down in this case. You will have the same result, because if the low voltage that is supplying the circuit is not present, then there is no high voltage present, etc.

  15. Looks like this has been here a while, so I will take a stab at it:

    Depends upon the circuit it is measuring. If it is not too fragile of a circuit, I guess you could just make a simple probe from an LED, a 1.5 battery, and two probes. If the probes are connected across an open circuit, the LED will not light. If it is not an open circuit, it will light with some exceptions. Depends upon the resistance of your circuit. So you would have to figure this factor in when making the probe as the LED needs enough to light it. On the other side of this fence, you do not want to add too much to the circuit which will kill the components in it.
    You really have not given enough information about the circuit to return with much more than this.

  16. Try this site: http://home.planet.nl/~meurs274/
    Some stepper projects with Atmel AVR. I know you have the 89C51, but there is enough similarity that this should be what you need. Basically, your port pins send the pulses and the ULN2803A drives the signal. Very simple layout. Even has a board layout in eagle that you can edit with the free demo version.

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