MP

I am certainly a believer in plenty of flux. Requires some alcohol clean up afterwards, but I always use plenty of flux. A gracious amount of flux when desoldering, tinning or assembling a board makes solder joints much nicer looking and much cleaner when you are finished. Gets rid of blobs and brightens up the look of the finished solder joint. A little trick I learned years ago when going through a course for MIL spec on soldering and assembly. MP

No. It leaves a nice clean shining coating of solder on the wire. First dip the wire in some flux, then into the solder pot of melted solder down to the insulation. Only dip it for a second and pull it straight up from the pot. When you pull the wire out of the solder pot, it will have a nice even coating of solder because the bare wire was evenly heated. Using a solder iron will many times give you a solder blob at the end. This is because of the excessive solder on the iron. Most any agency that makes cables for their products will use a solder pot to tin all wires before they are soldered to connectors. MP

Here is one like what I use on my workbench for tinning wires. I purchased mine directly from Techni-Tool. They come in various sizes, but I only need a small one. http://www.amazon.com/gp/product/B00011V070/qid=1149000405/sr=1-1/ref=sr_1_1/103-3893925-2095865?%5Fencoding=UTF8&m=A2QE1R98UNI0YZ&s=hi&v=glance&n=228013 MP

I recommend that you just go with the settings in the project. It sets the first LED for 8 volts and sensitivity of the circuit. The LM3914 data sheet will help you understand this better. MP

Sounds like you are just wanting to use a bipolar transistor as a switch for a relay. Perhaps this short tutorial will help. (attached pdf) MP Transistor.pdf

There was an article discussing this in "Motion magazine" in the September/October 1992 edition. It is Volume 8, Number 5. The article was titled, "Ferrofluid-Filled Stepper Motors" by - K. Raj and Richard Powlowky. I do not have a copy of the article, but perhaps you can find it with this information. Evidently, it is not too wild of an idea. ;) MP

I certainly have to agree on that point. For a one time board project, the cost of bits for 5 or 6 different hole sizes would not justify the cost to make 1 pc board. One could have a board house produce the board at nearly the same cost. (Hey, nothing wrong with a Chevy truck. Have a Silverado, myself.) MP

I wouldn't bother with the many square wave inverter schematics posted all over. Square wave is not good for some equipment. All AC appliances were made to be run on a sine wave. Although this does not matter for some equipment, it will certainly make a differences in others devices. You could see differences ranging from clocks not keeping the correct time to long term damage due to the waveform used. You can actually buy a sine wave inverter for less than it would cost to build one. MP

draggy, I am pretty sure 6 volts is a maximum value for your PIC. If your batteries are exceeding this and your meter is not showing it, this is not good for your micro. Check your spec sheet for more specifics on this. In most cases that I have seen, where a PIC gets hot, it is due to misconnection or the sink/source current of the pins being exceeded. The port pins are ok with being shorted, but you cannot sink or source more than 10 to 25 mA. Exact amount depends upon your micro. Again, look at your spec sheet. When you run the PIC in a breadboard with only the crystal circuit and power supply attached, does it still get hot? Members reading your posts can only make a guess, so it would be beneficial if you could show a schematic of your circuit as requested in a previous post. MP

ok.

Wow, I totally forgot about this thread since SM2 never answered. Yes, if one was to replace a low ESR capacitor with one which was not low ESR, this could certainly be a problem since ESR is the sum of in-phase AC resistance. However, I read the original post as replacing a standard electrolytic rated at 12 Volts with the same type of electrolytic rated at 50 volts. I do not see where there would be a problem in this scenario, so I had asked the above question. Not sure why SM2 thought there could be a problem in this case. I actually stock the higher voltage electrolytics to keep my stock to a minimum. The only place I see a concern is where the higher voltage rating has a larger physical size, which might take more PC Board real estate. Nice to see you are bringing some of the older posts back to life. MP

My 2 cents: One thing I like about the carbide bits better than the high speed steel is that they will usually break before they ever dull. With high speed steel, I noticed the bits would dull fast. Even more so if you use paper phenolic boards. This would end up leaving me some holes with black burned marks before I was able to change the bit. Nothing worse than a ruined board because your bit burned through it and left a black mark. I have never had a problem with wander, but I use a CNC drill station. I have a PC board lab and run a large qty of boards through it. Thus it is certainly more worth while for me to stock the carbide. It is interesting that you slow down your dremel. All professional PC board drilling machines run at around 30,000 rpm. What speed is 1/2 to 1/3 on your tool? MP

I would suggest that you try to make room in your schedule for at least one work study per year of your last two years. If you can put more time in, then all the better. It is hard to put a lot of time into work study because you still must maintain your other coursework. I will say this: Most of the technicians I have hired, have come to the organization through work study. It also gave me a chance to see how they would perform and how well they work with the group. I am also on the advisory board for the local college, so I see the benefits of work study throughout the Electronics Industry. You should make an appointment with your counselor or appropriate school representaive for this as they will be able to tell you more about the program in your school than what I could possibly know. Best of luck to you! MP

The answer to this question is determinate on the accuracy of the device. All of the devices you have listed are used in one lab device or another. For best accuracy, many will use a platinum probe (RTD). Many devices will use a thermocouple. More expensive thermistors can give you +/-1 deg C accuracy or better. So, it really depends upon the accuracy requirement. MP

Most colleges offer some type of work study program where you get credits for working in the field that you are studying. This is the best preparation. The employer benefits because they do not pay you and you benefit because you get credit for the work performed. You also get an inside look at your "soon to be" field of expertise. Get on a work study program with a firm that is in your field of study. It might turn into a job and you will be ready for the corporate world by the time you graduate. Even if you decide you do not like the firm that you worked with on the work study program, it will still give you much knowledge of what you will be up against after graduation. MP

I keep a small one on my workbench for tinning wire ends. Makes quick work of it and always makes a much nicer wire end than using a soldering iron. MP

Good to hear you are making progress! MP

I have never used the feature for pin 6. You will not hurt anything for trying it out. Perhaps you could add a shunt so that it can be high or low if you decide to change. Pins 4 and 7 are already at 5V because of RP1. Have fun! MP

If you have checked the time for delay on the pulses and you are confident that this is not the problem, I would check over the connections to the board and just make sure you did not miss something. Next, are you sure your 1 A power supply is sufficient? Depending upon the stepper, you probably have 4 coils per stepper. 3 steppers? That would be 12 coils at 160 mA. Seems like you need a minimum of 2 Amp. As a general rule, you do not want to run at the minimum. Most devices are engineered at 2X the minimum. I have always used an old computer power supply for running steppers. If you have access to one, you might want to connect the 12 volt connector to your project to see if you get better results. MP

I see no reason that this would not work. You also do not need the part of the schematic with the 555 if you will send the pulses from a micro instead of using the on-board pulse stream. In other words, you can eliminate U1, R1, R2, R3, C1, C2. You only need to write a sequence to J3-2. The stepper will make one step for each pulse. I recommend that you use a 50% duty cycle and a low frequency to start. Then you can speed up until your stepper starts to skip steps and back off. Change the direction of the motor with J3-3. When you connect 5 volts DC to it, the stepper will go in one direction and when you apply 0 vdc to it, the motor will go in the other direction. Connect pins 1 and 10 to ground. Tie pin 4 low (0 VDC). Leave pins 5, 6, 7, 8, and 9 open. This should get you started. Hopefully, if I have missed something someone else will jump in to assist. MP

Pinball machine comes to mind.... you know, those things that were popular before video games came around.. ;D MP

Have you looked in the projects section of this site? There is a link at the top of the page... or follow the link below to the digital voltmeter project: http://www.electronics-lab.com/projects/test/007/index.html This project will give you a LED display reading of your voltage. Not sure why you want different values, but if this is a prerequisite, you could use A2D into a micro with some internal calculations. You will also need input scaling since a micro will not allow for more than 5 VDC. MP

Yes, I am aware many things do not carry a patent. Thanks for the link. Mac L: Thanks for bringing up the subject of patents. "Patents in general" might be an interesting discussion for a new topic. MP

Thanks gogo, I forgot to mention the BCD to 7 segment display ICs. Shahzad: Here is a little diagram to get you going with the 4511 that gogo has mentioned. MP

How does one go about looking through patents? Is there a URL link that you know? I know that it is public knowledge and that you could go to the patent office to look through items by category, but I have not seen an internet link. Was just wondering if anyone knew. MP