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MP
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Posts posted by MP
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Andodizing and painting are just one aspect. Here is a thought:
If color is not a major concern, why not get some gun bluing or browning for steel parts, and/or, gun aluminum bluing for aluminum?
Wouldn't you have to keep up the bluing from time to time? Not trying to give you a hard time. I just do not know anything about gun bluing. I thought that this was not a one time process; that you have to continue to blue it from time to time.
MP -
Well I have finished my power supply and it works like a Charm :)
But I would like to add a digital panel meter that requires 5V power supply, does anyone have and good suggestions on how I should go about doing this.
P.S. this is my first project and I'm still learning
I have seen a good answer to this from ante in the past. He coils a wire and attaches it to the top of the transformer for an additional low voltage tap. Perhaps he can give you a little more instruction regarding this since I am only giving the information second hand.
MP -
How about the rest of the circuit? There is no transistor in the diagram you have posted. How can anyone tell you what you need when they do not see all of the circuit? What is the current consumption of your circuit?
MP -
No black magic there. You must have some reference that you are calling zero. Since all of these commons can be at a different potential, there is no "common" reference. Thus, your shield is just another voltage reference and is not protecting anything. If you want the shield to be at the same potential as the grounds, (you do want the shield to be grounded) you must connect all of the commons (grounds) at one point to insure they are all at the same potential. Then you have a zero reference and can work the rest from there.
There may also be other problems with the circuit, but this should be step number one.
MP -
Wow, expensive tip.
Yes, I use liquid flux on all my soldering. The core flux helps the solder to flow on the copper, but it is rarely enough. A trick I learned years ago. When I was going through MIL SPEC soldering coursework, flux always got me higher grades since the joints were always better looking. Try this for yourself. Flux comes in liquid form and also in pens.
The tinning block will help out a lot, I think. I have used a tinning block to revive some pretty bad solder tips.
MP -
Shaiqbashir,
Where do you need 13 volts in your circuit? You only need the final conversion to 5 VDC for the micro. Unless there is more to the circuit that you have left out, you could simplify this and just use a 5VDC conversion. Regulate a 9 volt battery down to 5. In this case, forget the LM317.
MP -
Happy Birthday, Rhonn!!
MP -
At this point, you really need a new tip. Sanding down the tip just causes more harm. Are you using a wet sponge to clean the tip whenever you get burned residue on it? This helps. One nice tinning trick is to get a nice blob of solder on the tip when you are done with it and then let it cool down. The next time you use the iron, it will be tinned well.
Another thing that you can do is to keep a tinning block handy. Here is an example: http://shop.vendio.com/LordMikal/item/693681018/index.html
Then whenever the tip starts looking grey, rub the tip against the tinning block. It will look like new again. And lastly, use plenty of flux when soldering. This helps a lot. You will find that the iron needs less time to make a good solder joint and thus there is less build up.
Hope this helps out.
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I would have all commons connect together at one single point as I indicated above. All shielding must be at some potential. You want it to be connected to common of all devices.
MP -
Should work fine.
MP -
This is true. Even though we have attributed the Watts calculation with ohm's law and most of the ohm's law calculators include it, power calculation was not part of the original ohm's law. It is an extended calculation. ;D
MP -
If it is only a 0 to 5VDC signal, you can use a shielded cable to shield against rf. Connect the shield at one end only to keep from producing ground loops.
If you are experiencing signal loss due to length, you can increase the current to the pot to compensate.
If the length is too long for this, you might want to consider a digital pot with a memory. However, this will increase the expense of the device you are making.
MP -
http://www.surplussales.com/Inductors/Ind-SlugTu/Ind-SlugTu-6.html
http://www.surplussales.com/Inductors/Ind-SlugTu/Ind-SlugTu-4.html
Hope it is helpful.
MP -
Even when you separate the digital and analog grounds, all common connections are put together at one common point. In this case, you basically have two electrical circuits interfering with each other. This is why I suggested that you post the circuit. I certainly understand if you do not want to make this design public.
MP -
As a side note... auto routing isn't used very often in analog design, it's more of a digital thing.
Are you kidding? I ALWAYS use auto-router. Analog, Digital, and Mixed-Design. You must not put together very complicated circuits if you manual route all of your Analog boards. ERC and DRC eliminate any problems that you might encounter. Netlist tells you if anything is missing. If there ever IS a problem, the few traces you might go back and re-run are much less time consuming than manual routing an entire board design. If I ever caught one of my Engineers manual routing an entire board layout, he would be looking for another job. That's MY time wasted.
MP
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The wall wart will give you all the informatin you need. If it states 9V@500mA, you just need to use a resistance that will cause a 500 mA load from 9 volts. Make sure your Watt rating on the resistor is high enough. You can calculate this on your own. It is easy with ohm's law, and then you learn something also.
<Time to brush off the dust on the old ohm's law book.>
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Original post...
...but not ICL 7107, 7106. thks
Peron: Perhaps you could give a hint as to what IS available in your market. As ante has mentioned, 7106 is the best alternative to do what you are trying to achieve. Samples from the manufacturer are available for this IC in most places of the world.
MP
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You could try separating your digital and analog grounds and if needed, build shields around the motors. Perhaps you should post information about the electronics. It is possible that the electronic noise is transmitted through your circuit. If this is the case, all the shielding in the world will not help.
MP -
Queen,
Frequency that the motor can handle is pretty much different from motor manufacturer to motor manufacturer. You will have to make some adjustments when you make this circuit. You should make the frequency adjustable anyway, so that you can use different speeds. I would recommend that you start with some obviously too slow frequency, like 500HZ and work your way up until the stepper starts missing steps. Then, you need to back down to a slower frequency.
In regards to the battery question, 2.5A per motor is sure a lot to feed from a small battery. Are you sure you need this much current? If you are using 3 motors @ 2.5A each, that is 7.5A consumption from your 7Ah battery. Keeping in mind that the battery will not work well at the 50% level or lower, this gives you less than a half hour of usage. I would recommend a larger battery, such as a deep cycle RV type or even a car battery for the initial design. I assume you do not have AC power at the site. Perhaps other members will have better ideas.
I can certainly give you suggestions and guidance, but I do not have the time available to help with the design work to program the PIC. www.avrprojects.net has some sample basic code to run steppers with AVR micros. Perhaps you could port this to PIC or find something similar on the web in the language that you will be using. It sounds like an interesting undertaking and I wish I did have a little more time to help further.
Good luck!
MP -
You already have the solar cell to buzzer working. Just add a comparator circuit between the solar cell and buzzer so you can adjust the threshold. In fact, you could even use a separate photo cell or LDR to trigger the circuit from light.
MP -
I have never been asked to pay postage on samples. Not from National Semi or any of the other manufacturers. However, I have a business. Perhaps you tried to get samples as an individual or student?
MP -
If you mean to convert the current on your present system to a voltage, the simplest way to do so is to drop the current across a load resistor and measure the voltage.
If you mean is there an easier way to get a 0 to 12.5V output from a 0 to 900 ohms resistance, I am not aware of anything simpler than using an op-amp.
MP -
I must not be understanding what you want because it sounds too easy. Why not an op-amp with your variable 0 to 900 ohms in the feedback loop to give you 0 to 12.5V?
If this is not it, maybe you should show what you already have and explain what you want to be different. A drawing works really well.
MP
Electromagnetic field interference.
in Electronic Projects Design/Ideas
Posted
No myth...just "Common" sense ;D
That is what I said...a "Common" point. You do not have ANY point that is considered to be a "Common" point in this diagram. All systems are acting independently of each other and thus, they are all doing their own thing....not working in unison, if you will. How can you bleed the EMI to ground when the ground from the part of the circuit that is causing the EMI is at a different potential than the ground on the part of the circuit you want to bleed it from?
Ground is the best place to make these commons since other potentials can get complicated and can cause one voltage potential to interfere with another if you do not connect everything correctly.
MP