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• Users: faust9
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1. ### Solid-State Inclinometer

Analog is usually pretty good about selling in small quantities. I bet you could save a few bucks by getting them from Analog instead of digikey. Here's and EDN article on accelerometers. http://www.edn.com/article/CA472836.html
2. ### Why would a circuit have a zero ohm resistor (3 black bands) in it?

Zero ohn resisitors are used as jumpers.
3. ### Differential amp

No file attached
4. ### Bipolar transistor amplifier

I'll admit I didn't bother doing any calcualtions so take this as a best hunch: With no input on the base you should have ~7.5V out. The transistor should probably be biased somewhere in the middle of the Q-point thus the CE current should induce about a 7.5V drop across the Collector resistor...
5. ### I'm stuck on boolean algebra, it has 4 variables!

You do get the right answer if you arrange things logically: ______________________________ | \cd | |ab \ ________________________| | | cd | cd! | c!d | c!d!| |______________________________ | ab | 1 | 1 | 1 | 1 | |______________________________...
6. ### I'm stuck on boolean algebra, it has 4 variables!

You don't need the B! though. You're adding complexity by having it.
7. ### I'm stuck on boolean algebra, it has 4 variables!

AND the MSB with each of the two preceeding bits and then OR that. (AB)+(AC) will yield a 1 when the output is greater than 9.
8. ### How do you know if you should use 3 variables for 4 variables in IC design?

000---0 001---1 010---2 011---3 100---4 101---5 110---6 111---7 1000--8 1001--9 Counting in binary.
9. ### Rechargeable Batteries

What is the best most cost effective vehicle sold in the world today? There is no such thing as the best in engineering. What you do is take your needs look and at your financial situation. You then determine the solution that fits your pocket book and gets you as close to your needs as...
10. ### Whats the electric part i need?

Computer fan motors are usually dc brushless. changing the voltage does not change the speed. The speed of the fan is dictated by a little controller attached to the fan motor inside the fan housing. Variable speed computer fans have a third wire that you can use to control the speed of the...
11. ### Making an external HD

This is one of those times where the respons is "If you have to ask then you don't know enough to begin with." Basically, you'de need to understand the USB protocol as well as the IDE protocol---both hardware and software---before even attempting such a project. You might be able to get away...
12. ### Why do powerlines hum?

Because they don't know the words.
13. ### Base diodes in FETs

Your internatiional Rectifier reference describes the clamping zener in section 5. Not all MOSFETS show the clamping diode as part of the schematic symbol because it was not a standard feature. Most MOSFETS made today include a clamping diode to protect the MOSFET substrait now though. In the...
14. ### Base diodes in FETs

The source to drain diode(also found in some Power BJT's) is sometimes called a flyback diode. Mosfets are really sensative to overvoltage conditions so, to prevent reactive load spikes from destroying your MOSFET(or darlington pair) a diode is commonly added across the source to drain(or C to...
15. ### Inductance of transmission lines in vacuum

Because the size of the font does not alter the bandwidth needed to transmit a message while a photograph will. Additionally, allowing photos means you must moderate all photos(lots of work) or you must put up with the occasional naughty picture(not good when young ppl are around or foreign ntls...
16. ### Buying tools and supplies

Why complain you do get 4 or 5 resistors for that dollar :devil:
17. ### Buying tools and supplies

I can't second enough how gret metcal irons are. Pick one up on e-bay if you can. Get a lot of tips too. I bake a lot of my smt now but before I set up and oven I used my metcal with great results. Also, the old metcal still sees a lot of use for rework and through-hole soldering(I need a wave!)...
18. ### Re: DAC0832

Digikey has them: http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=3780&Site=US&Cat=31785614 So does Newark...
19. ### Transformer E&M Question/Story

In response to your first question, I'd use whatever module your phy xceiver calls for. http://www.alldatasheet.com/datasheet-pdf/pdf/NSC/DP83861.html The xceiver from national spells out which magnetic module(s) to use. Now, from the looks of things, the autotransformer is stepping up a...
20. ### Need Circuit help for Airsoft Project

Not .5A, .5mA. The pdf above was for the darlington you have in the schematic. I'd use the 2003 personally. Motors don't draw voltage they draw current and the 1700mAh is how long the battery pack will last i.e. if your motor draws 1A then the battery pack would last 1.7 hours(not really...
21. ### 8 bit switch? does it exist?

I still don't see the need for 2 244's. You said the RAM does have an enable line then there is no real need for a second 244. ADDR:DATA buses used to be split by using only one latch and an inverted enable line. Without seeing your schematic or knowing the exact details I can't say for sure...
22. ### Need Circuit help for Airsoft Project

Here: http://www.fairchildsemi.com/ds/2N/2N6427.pdf Look for the spec labeled V_BE(sat) which is 0.5mA. At the saturation current the voltage V_BE is 2.0 volts. Your voltage drop across the CE junction will be about 1.5V@500mA so account for that also. If you use a 5v relay it will need 5v...
23. ### 8 bit switch? does it exist?

How do you not have an enable available for your RAm or LCD? Your system will not work unless you have some way of telling the RAM/LCD when to read data and when to write data.
24. ### 8 bit switch? does it exist?

I explained it above. You don't need an 8:16 MUX to do what you've asked about. You only need an inverter on the 8th bit (the free bit you mentioned a few posts back that you wanted to use as a switch). Send the 8th bit to one device directly and send the 8th bit through an inverter (74hc04)...
25. ### 8 bit switch? does it exist?

Read my post above.
26. ### 8 bit switch? does it exist?

Use the 8th output to switch between the LCD and the RAM. Ram and LCDs have an enable. Split the 8th bit into two lines. Invert one of the lines. Use the inverted line to enable one of the devices and the noninverted line to enable the other---this is assuming both devices use the same logic...
27. ### Need Circuit help for Airsoft Project

I hate to be the fly in the ointment here but I don't think a 555 will even drive a relay by itself. You probably need a darlington between the 555 output and the relay. Try getting a ULN2003A if you can. Also you have the relay going right to the 555 timer output---this is bad for most IC's...
28. ### Inexpensive yaw rate (azimuth) sensor distributors?

My team uses these on our race car. The car's data acq system is not mine(I do engine controls) but I know we use a few accelerometers to determine evrey conceivible aspect of the cars orientation as well as suspension system orientations. I'll talk to the person who actually works with these to...
29. ### Inexpensive yaw rate (azimuth) sensor distributors?

Most accelerometers can detect their orientation by measuring the acceleration due to gravity so one would suffice. They are actually quite accurate as well.
30. ### Serial to USB

No, you cannot wire the serial connection directly to the USB cable. You have to use a store-bought adaptor or, make your own using the above FTDI(or similar) chip. The best analogy I can give is that you can't take the engine out of a Ford and expect it to fit in a Chevy. You'd need adaptors...

37. ### Electric motor + 12 volt battery ?

Yeah, you can use solar cells. You'd need enough cells to supply sufficient current to be useful. Matching solar cells is not easy or cheap either. You can't simply group 10 solar cells together and expect to charge your battery. Just to give you an idea of the costs involved in using solar...
38. ### Electric motor + 12 volt battery ?

Is it possible? Yes. Will you gain anything? No. The power required to drive the alternator will come from the battery. Alternators are not perfect devices---they have both electrical and mechanical sources of power loss or rather some of the energy put into the alternator is converted to heat...
39. ### Blowdryer issues

The "what's that" is the vibrator. There is a little motor that is out of balance inside that little battery-like case. If you were to cut the little wires and connect then to a AA or AAA battery then the motor would start to vibrate. Your previous picture of the bottome side circuit: If I...
40. ### Solenoid question

If you align the magnet so the same poles are close to each other initially then give a quick pulse of electricity (On/Off) to start the magnet on its way then switch the field when the magnet is a little greater the 1/2 through the solenoid then you should be able to do it. You'd need to...
41. ### Solenoid question

Well, if your working with weak magnetic field(yes the copper will affect the strength of your magnet) then you'll want to use magnets as your projectiles probably. Look into cow magnets because they are strong slender and cheap. If you want more oomph then try Neodymium magnets. You can get the...
42. ### RF gurus-A question from a wireless dullard

Anyone? Bueller, Bueller, Bueller. Well, I guess it serves me right. I should have payed more attention in class and retained said information---and text---longer than 14 seconds after the final.  according to this site...
43. ### RF gurus-A question from a wireless dullard

RF gurus---A question from a wireless dullard Ok, I need to collect and send data to/from a remote device about 500ft away. I'm looking for a single IC transceiver in a small smt package if possible. I'd like a transceiver that handles the communications with little to no control from either my...
44. ### Measure of Volts / Amps

You misread. The units given were c/s not CM. An amp is a coulomb/second or C/s.
45. ### 365kJ Capacitor Bank

He has two caps (In parallel I presume) not one.
46. ### Building An Amp Hour Meter

You're measuring the voltage dropped across the 0.1 ohm resistor only. The 10 ohm resistor will drop most of the voltage while the 0.1: V_{0.1}=\frac{V_{source}}{R_{10}+R_{0.1}}*R_{0.1}}=0.049 Since you know ohm's law and you are measuring the voltage dropped by the resistor and you know the...
47. ### Building An Amp Hour Meter

Don't forget you also have an opamp (10x gain IIR) and you'll need to multiply each calculation by the time required to complete one sample. The opamp will be easy to factor in as will the timeing. once you have your code you'll then be able to figure out the average time to complete a cycle...
48. ### Unmatched voltages on a transformer's primary coils

1) If the generator can supply that much power and if we're talking about shorting the generator to ground then the answer to your question is yes. 2) Yes, the generator would slow down to the point where the mechanical input equals the electrical output---Essentially, Power in will equal...
49. ### Building An Amp Hour Meter

I would suggest coding in asm because your chip only has 1Kx8 of flash memory to work with. You can do it in C; however, writing code in C as efficient as asm code takes as muck time and effort to do as writing in asm to begin with(it can be done though). Now, your chip comes with a default...
50. ### Unmatched voltages on a transformer's primary coils

Please rephrase your question. Do you mean connect a cap to a source only? Since I=\frac{V_b}{R}e^{-t/{RC}} your question is meaningless. the actual answer to your question is somewhere between 4.6 and 5 \tau depending on how accurate you want to get (you can go greater than 5\tau if...