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Everything posted by Tony_Stoynov

  1. Hello, You need to control all leds together or you must be able o change each led? The first is easy. Actually you have several possibilities, from custom DC/DC controller to using of standard LED controller you can see this type of controllers from TI Company. You must know that the White led, actually all leds must be controlled via current. You must to have a several current sources for each group of LED's in series. In my application I am using either BD9778 - ROHM DC/DC controller, either TI controllers, this for application that must control all leds together. To build a current source generator you may use any DC/DC controller. Because the DC converter your input voltage can be in wide range. Because the number of leds is big, I can suggest you to use something like a matrix control.
  2. Hi, what exactly you need? About the project, this is a simple and easy to realize. Because you have RS232 I hope you need only two point connection, because multi point with RS232 is a bit difficult. First think is to get a decision what type be a protocol of communication, master/slave or not. When you have a master slave protocol, one master initiate the communication. Another way is any device to initiate a communication. Depending of the application you can use one or another type of communication. Next step is to create a protocol. The core of protocol should be something like this : Byte 1 Start Byte Byte 2 Package length Byte 3 Type of package Byte 4 Command Byte 5 - Byte n data Byte n+1 - CRC 16 Byte n+2 CRC 16 If you have a multipoint communication then is usefully to have a sender address and recipient address. Also depending of data length the CRC can be 8 bit or 32 bit, also you can implement another type of data protection. When you send a data you should use change some of the data. Lets say that you start byte should d be a 0xFF then to prevent false in protocol form data with value 0xFF you should add extra byte. For example your start byte can be 0xFF, 0x00. Each 0xff value n your data you should replace with 0xff,0x01 for example. You will know exactly what is the start byte and what is a data, without chance of mistake. If the protocol is master slave, the master should send some command or data to slave, and slave will return some result, or will execute some command. If the protocol is not master slave, then you must add some extra logic before start a data sending. First you should check the line, if you have a simple RS 232 point to point this not a problem, but if you have a multipoint network communication this is a very important. First you check for the another device transition. Second you start a communication. If you find a data transition you should wait a random number of time and again tray to send a data. Also you should check for the collisions. No matter that the chance is very low, is possible two device to start communication on to same time, no matter the line choking. In that case your should detect a collision, after that you must wait a random time and try again to sent a data. The type of protocol is depending from your communication speed, and application. In critical application I am use master slave communication if have not other requirements. In some case each device should be bale to initiate a communication, in this case a high speed communication is a good solution to solve the problem with a collision and decreasing the real data rate. p.s. excues me if i have a writing errors, i use a spell check in MS word, but i have not time to read careffully the result of speling.
  3. What you need to do, you need radar to determinate the object position and distance to, or just to calculate the distance?
  4. If you still look for company that is able to design this for you pls send me a PM. Below you can find similar product with a 3x3W white led’s
  5. Hi, This chip is MOSFET driver, not a motor driver. The mosfet haven’t the gate current, this 3A impulse is only from the capacitance between gate and Source. What type of motor you will drive?
  6. Hi, This is to same like a laser device. Laser device is better, because the light ray is more coherent, and will be an easier to obtained big distance. The problem their can be the noise, from son, from lamp, from headlight. To reduce this signal you must use a more intelligent sensor. If you use industrial this problem is solve. If you make own, you must use the impulse mode with auto calibration. The bigger problem is if you have two cars with distance small that car length. In this case your sensor will detect front of the first car, and rear of the second. If you want to solve this problem, then the task is a more difficult. One way, but is not very easy is to use optical recognition. Second is to use RFID tags, but this is ....not very accuracy, because depend from the car position, and weather you can have a different distance to tag reading, but if you get starting time and ending time, and give the average between to car time, the error will be a small.
  7. I not sure that you need a model for the processor, and I am not sure that Intel can provide some model. They has internal model, but they is not suitable for the PCB design. Actually you no need from this model. Only one that you need is a good PCB soft, in your case the best decision is a Mentor Graphic. You must simulate only the signal quality and delay. Every chip has a DC and AC signal requirements, when you design your board you must read his requirement, and be under the critical parameters. When you construct the motherboard you will has two big problems. First I a time delay and signal form. This is depending from track length and form. If you has a track with different length and form you can have very big different in time delay. If you’re track ahs a big inductance and capacitance, then the front of the signal will be bad. The second big problem is interference between signal, and EMC compatibility. The Intel a provide simulation model for I/O but actually if you look at chip documentation you can see this models, and use them. This is not easy task. I can suggest before start the design to look at Intel reference design; many of company use directly Intel reference design and make only small correction.
  8. HI, IR optical barier is very suitable. Way you think that F1 timer is expense, in this timer have not nothing special. You can do this very easy. What you ant to create, or how. You want to use standard device, like a sensor, timer etc and just connect them, or you want to make the timer and sensor?
  9. Hi, you can made different construction. The traditional conveir belt is a one or two draving wheels, depend from this one or two direction is movement, and several secondary wheels between them. The belt can be set in motion with friction or with cogwheel. In your case i think you can use cogwheel construction, from old donuts cooking machine, they use a cogwheel and mortiser belt. You can also made a simple construction with two pulley and wire. To drive the DC motor in only one directin you will need relay or transistor. To detect the position yu can use the optobarier sensors.
  10. Hi, presured air, from compresor, via reducer, in compresor tank the presure is around 6 bar, after reducer valve the presure is below 1 bar. But now i think taht temperature of air can be higir that room temperture becouse the compresion, and this may be is a reson for the voaporation.
  11. Hi, look at this topic : http://www.electronics-lab.com/forum/index.php?topic=6246.0
  12. Hi, nobody ..... to get the answer must have a question. Type of the OPAMP, and signal, for example LF411 : Inverting Small signal ~ 200 nS Non Inverting Small signal ~100 ns Inverting Larg signal ~ 1.8 uS Non Inverting Large Signal ~ 1.8 uS Curent Limit Mode ~ 10 uS
  13. Hi, the MP is right, the fericloride is saffety. About the ventilation, i has in the pas thank with aeration, and can say taht aeration increase the voapours.
  14. Hi, the RS485 is very good decision. Afcourse you can use CAN but if you have not a controller with a can module will be a needless work.
  15. Hi, if this is only one way connection, you can use the RS232 with a current loop, or RS422. If you whant a real multi node network, then RS485. If you want something a bit hi-tech you can use a low speed optics, HP has a this type of trancivers, actually this is the agilent, a HP company.
  16. Hi, you whant to know what type of NVRam you can use, or you have specific question to some technology. Some producer, like a Dalas-Maxim has a NVRam on chip, with integrated battery. The motorola, and some other producers has a magnetic ram, this is very good decision. You can lok for a MRAM or FRAM technology.
  17. Hi, why you used a standard PC board, why you dont use some industril on board PC. Many of them use only 12 or 12 and 5 V. Something like a Arbor EmCore 615, this is Via based PC. Has a many other company that produce this type of board, they is not very big, used only one power suuply, n some case two, and is mre reliable. The ony one disadvantagem the price is higer :)
  18. Hi, I don't know where in the US you can buy this, has a different company that have a catalog for the chemical, but i don't know how you can by something from them. And they price is higer, becouse they material is very clear for laboratory analysis. I know that H2O2 is used in pharmacy industry. The H2O2 is used in hairdressing too, but they used 12% or 18%. p.s. about this solution, this is not a suitable for the etching tank. You must use how many how you need for the board. When i used this solution use a flat tub. I put the board in to the tub, add H2O2 around 5-10 mm, and then add the HCl to the moment when start a fast reaction /you will see a many small bubble/. Has a similar solution for industrial use, but with different proportion, 3 parts HCl and 1 part H2O2.
  19. Hi, did this is a etching tank with a pressure air ? If this is it, then not only the heat well be a problem, heat will increase the temperature, and this will increased the evaporation. But the pressure air will have a more strong effect in this direction. You must have a very good ventilation to save your health. Actually the feric chloride is not is not a very harmful, and not a dangerous as a nitrogen acid, but you must be carefull with a vapour. In normal temperaute, this is not a problem, but with aeration, and high temperature this may be a problem. Have a some other way for etching the PCB. Different alkaline solution. Have one more very fast method, and not a very dangerous for hand .. but must have a good ventilation. H2O2 + HCl, use 30% H2O2 and 30% HCl in proportion 2:1 or 3:1. Must know that this solution is very unstable, you must made it before using. The solution is good to be cold. If you have old refrigerator, you can store the botle with a HCl and H2O2 in refrigerator. This is a very fast method, compare to concentrate nitrogen acid, but is more safety. Just remember, you will need a good ventilation.
  20. Hi, mm yes i Living in Vegas, but my native language is not English, i am from Bulgaria, and actually 7 months ago my english was like your Bulgarian language :) I use Bulgarian dictionary. About the language, i know that my english is not good, i try to improve it. But the syntax error very often is not from ignorance, may style of typing is the reason. The situation in bulgarian language is to same, i make a lot of error when i typing, and after this must correct my errors. And i try to do this and in forum, but how i say, some time i have not time to do this, but i want to help to somebody .. may be better to write my post when i have a time ... i never not think about this.
  21. Hi Staigen, yes, you are right, excues me for this, i have too the dictionary, and translator, but not every time i have time for this, but in the future will try to correct may errors. p.s And i have one more problem, i use the HP NX7010, this laptop has a some very strange keyboard, if not press the button in the center you not have a simbol ...for this reason when i write fast very often i drop a letter.
  22. Hi, yes, i try to say above to same, not is good idea for any part to work closely to the maxium parameter, in the case with 78xx the surface temperature was 80 C, this is two time lowwer, and i think is acceptable in some cases. About the problem with a regulator and heatsink without bolt and nuts, ooo i see this problem no once. Some times i think in fabric no put the bolt when made the assembly, and if they have not a good QA,is easy this product to going on the market. In some other case, the device is repared from sombody else, and may be they think that this bolt and nut can be missing. This ia a big problem with a maintenance. Have something other, in a different devices enclouser is used to despare the heat but after maintenance procedure the technician put just 2-3 screw, becouse this is a easy and then the thermal resistance between enclouser and thermal source is a very big, and .... after several hours or day, some times after several month the device did fail.
  23. Hi Ante, thanks for the answer, about the temperature yes, if is possible i put the all part in goot temperature condition, if is a possible, i know how temperature reflect over reliability, iuse the Item software for reliability analisys. But sometime, in some case have other reason, price, space .. actually this si s a two generral reason to put some device in not very good temperature condition. I design the different products, and not i give a decision about price, and demention :) Abut the relay, yes the problem is from coil, and how i say i have a Epcos 380 V suprestor, but this not solve the problem, may be the speed ov increasing the voltage is was too high, and generate strong interference before time needing to supprestor to switch on. I am very happy that have a post, i solve all this problems a long ago, but may be some other peopel wil have this, or similar problem, wil be good if my or your experiance can help im to olve the problem more fast.
  24. Hi, yes, you a right, but i give this 2-3 W as a value to clculate eventual different between case temperature and crystal temperature, im sure for the case temperature, becose i use a thermometer. The chip separate some power via the PCB. And total power over the chip .... i not remember, in this device i have one PIC at 20 Mhz, one MAX232 and one LCD without backlight .. and several LED, let say that led have a 10 mA consumation. The PIC, MAX and LCD not have mre that 40-50 the result is 60, the input vltage was 24, then power over the regulator is (24-5)*0.05= 0.95 W. I dont know what is the PCB termal resistance, it's no very small, but now i thnk that 80 C is a normal temperature, in the case the chip must be aroun 85, that si twice less that maxium. I know abut thermal cutoff, but in this case i think have not a reason for this, i create this project many yaer ago, and have not a pcb to check again the chip temperature, no matter, i think this is a not a normal chip behavior. I have this problem only one time, but this can cost a time, after this i chek not only for the bulgarian chips, becouse they not in the production, but still can find it in stock, i look for chip from good company. But thanks for the answer, this can be very helpfully for sombody, i remebmer .. may be 15 or more yars agoo i made a audio amplifer with a OU and BD139, then i los some time to understand what is th powr, termar resistance, and how they reflected over the ca temperature :), from this moment, to today, i made a thermal calculation for every circuit, and if more complex with a active cooling, use the FlowWorks soft.
  25. Hi, thanks for th post, i know all this, but i just what to share some my experiance. About temperature, yes the crystal temperatur is higer, but this is temperature for junction in data sheet, the thermal resistanse junction-case fot TO-220 is a 5 C/W. When the package is 80 C, the junction temp not be very high, specially in the case that i not have a heathsink. The power over device is no more that 2-3 W, this give the 15 C different between case temeprature and juction temperature. This problem i think is connect to chip manufacture, sombody else can be have a similar problems, i just share some strangese from my experience. About noise problem, ESR not sole the problem, actually the low ESR electo have a too big inductance for this signl, i put a tantal capacito, put a several eramic, but this not solve the problem, only LC filter befor transformer. Yes, i not write this, but i has a suprestor on the relay, Epcos suprestor, 380 V .... but this not help me. About main filter, yes, how i say this solved the problem, but this was a more costlly decision, i just change the regulator fom linear to switchin mode.
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