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About xenobie

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  1. I have a project which required 3.3v (170mA), 5v (1.2A), 12V (not sure yet). For the 3.3v I am going to use an AMS1117-3.3 which is more then enough so this is not an issue. I have 2 questions mainly as follows: I want to use 8x of these stepper motors driven by 8x DRV8825 and I am not sure if the specifications are correct but could it be 50mA each totaling 400mA @ 12v? I have a couple of AMS1117-5 as well and since they are a max of 1A, can I chain these? if not what do you recommend?
  2. Hello all, Ok so I have a project, I am not in a hurry to learn and the main purpose here is to learn. But I need to learn the right way. Basically my question is this... What is the difference from an Atmel 8 bit uC to an Atmel 32 bit uC from the Programmers Perspective? As in, what is the difference between a 'hello world for 8bit' and 'hello world for 32bit'? What is the difference for a complex system written for 8bit and the same complex system written for 32bit? I chose Atmel because this is what I have available and I don't really want to change. Also to save you time, do not explain stuff like, GPIOs, Frequencies, ADC, etc.. etc.. this is all in the datasheet 8) Thanks all!
  3. Thanks Hero for your reply. I will read about these level logic mosfets later on but I have a feeling they switch on / off rather than turn on slowly etc... Regarding the 12W resistor, you are right. 1W should be enough because I'm only going to pulse 1A for 100 - 200mS Thanks :)
  4. That's what I thought.. so is there any other way to protect your circuitry apart from using opto couplers and 2 different supplies? I must use only 1 car battery. Thanks for your reply too :) X
  5. Hi there, Ok I did this with the right parts in about 10 minutes. Very simple. You need to buy an Arduino. http://www.arduino.cc/ And either a Wifi Shield or an Xbee Shield. Let me explain in simple terms. The Arduino was designed to have small boards plugged into it. These boards can actually stack on top of each other. Such boards are called SHIELDS. So in simple terms, if you want to communicate using bluetooth, you need to buy a bluetooth shield. If you need GPS and GPRS, you need to find a GPS/GPRS shield. If you need both, you buy both and stack them on top of each other. Now I mentions Xbee... http://en.wikipedia.org/wiki/XBee Xbee is actually a TX / RX Device which is easily programmed using the XBEE software. An Arduino can be programmed using a language called Processing (its actually a sub set of Java... meanings its identical to Java but with limited features). Recommended Shopping List: 1. Arduino 2. Xbee Shield (this is just a board) 3. Xbee Module (the actual transmitter and receiver) You must make a lot of reading too because I cannot possible tell you everything here but for example Arduino is open source, meaning there are many different sizes, shapes and uses for Arduino as everyone can make his own. For example a lillypad is an arduino on a circular board which can be implanted into your jacket or whatever crazy idea you want to think of. Also Xbee there are 2 versions. Version 1 has a different use the Version 2... I would go for Version 2 as its slightly more complex, but the main purpose is to make a MESH http://en.wikipedia.org/wiki/Mesh_networking which is your case. Any ways Good luck and do a lot of reading.
  6. Hi Guys, I have a couple of questions but I know you might be busy, I would appreciate ANY answer even for 1 question. :-* I have a situation where I would like to switch an electric match. The typical trigger power for such a device is 12v 800mA - 1A. I have three questions for this. 1. I was told that Mosfets are better than Transistors for this situation. Why? Is this true? 2. I need to choose a Mosfet which is fast and reliable. I need it to turn on fast but its only going to turn on once in an hour's time, and its only going to be used for a few mS until the match is lit. 3. Lets say I connect 12V DIRECTLY to Drain/Collector, and Ground DIRECTLY to Source/Emitter and when I switch the Gate/Base an 'infinite' amount of current passes to the match however it takes mS to burn and once it burns the current flow is not possible anymore. Would you recommend such a design? I calculated that to put a resistor to limit the current to 1A, it needs to be at least 12W which is huge and expensive. I need to switch around 300 of these... imagine having 300 resistors of 12W each ... :-\ Any other Ideas? Info on Electric Matches for your information only: http://en.wikipedia.org/wiki/Electric_match
  7. Hi Guys, As I understand opto couplers, their main use is to isolate a circuit from another,mainly for protection purposes. In my case I have an Arduino which controls a couple of shift registers (74HC595) which trigger transistors and I would like to protect the Arduino and the Shift Registers from any damage. Since the Arduino works with 5V, and the Transistors will be switching 12 - 14VDC, BOTH INPUT and OUTPUT will be using the same ground. My question is this. Does it make sense to use an opto coupler since I will be using the same Ground? I mean is there any protection at all? Some more info on the power source: The main power source is going to be a car battery OR an ac transformer converted to DC. For the Arduino I am going to get this voltage and stabilise it using a 7805. Thanks a lot 8)
  8. Dear Friends, I am building a device which requires 12VDC however it can either be powered by a car battery which is already 12V OR by 12VAC (or maybe 16VAC) At first I thought it was simple because I can simply put a bridge rectifier and a 7812 and AC or DC won't effect my electronics. But now I am thinking about the voltage drop of the 7812 and the diodes. As far as I know, the 7812 needs at least 1.2V more in order to be able to regulate the voltage. So when using AC, there is no problem ... but with the car battery ... im clueless!! Thanks X
  9. Hello all, I have a project at the moment and everything is to work from a single 12V battery. Now I am using an Arduino which has its own 5V regulator. Since I intend to switch some ICs and a relay, I can't just power everything from this poor 5v regulator. Can I for example have a transistor's base switch on using the output from the uC (Arduino), have the emitter connected to GND, and the collector-relay-coil take voltage directly from the battery? Another similar scenario is to have two 5V regulators (1 on Arduino and 1 for some ICs) both of which taking power from 12V battery and have the Arduino "mix" its 5V with that of the ICs ?? Sorry if this is silly but I know that this might be fatal to some components in certain circumstances. Thanks X
  10. Well why not use Arduino man? Its open source, you can build and modify it as you like without breaking any laws and you can find a MILLION projects using Arduino. It very easy to control too. I'd say that you can actually get up and running with the code in less than 4 hours. good luck
  11. Hi Hero999, Thanks for your constant cooperation. There has been some development since the last post. So I intend to use an Arduino to connect it to a 74HC595 Shift Register. I will then use a PC817 Opto Coupler as this is fairly new, small and fast. I haven't thought about the output of the opto yet but most probably I will drive a mosfet to trigger the output. So for speed, that's settled. Regarding the Safety of this project well basically it will be triggering explosives such that if an explosive is trigger abruptly, it might kill someone. I have given a lot of thought about safety and what I intend to do is to actually have a relay which supplies voltage to the output (the mosfets which I have yet to think about mentioned above) will only be switched when the system has the green light. Furthermore once the relay has been switched, I still cannot afford to have the outputs go off because even if all humans are clear of the area, I still need to have perfect timings. To summarise the safety issue, I wouldn't worry about killing someone as the Arduino controller Relay will not supply voltage at all HOWEVER a clean output is a must. Not only this, I need to monitor the outputs to know if everything is going smoothly. Thanks once again, any design ideas are greatly appreciated. X
  12. Hey Hero, Thanks for your reply. Ok so basically I chose the wrong symbol when making the diagram. The current design is now slightly different. I basically have the uC -> Shift Register -> Opto Coupler -> Transistor The loads are all 12V 50mA so no need for large switching stuff but it is a safety critical application and I do need monitoring and the like. How do I do this please? Any ideas where I need to look at? I will look for BJT in that case. When I said fast, I really meant fast response time. In fact in every application each output will only be used once. The system will then need to be reset. Much Obliged.
  13. I have a small update. A friend of mine just introduced Shift Registers to remove the grid thing.... any other ideas?
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