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  1. Morcego

    Need advice on quartz infrared owen for electronics

    Dear all, I know little(nothing actually) of infrared heating. But i need to build a machine to solder surface mount electronic components. The purpose is to build a kind of tunnel with quartz infrared elements inside. The board will travel slowly inside the tunnel and the solder paste will be...
  2. Morcego

    Help with 433Mhz Antenna Location

    Hello, I have some degree of experience in electronics, buy know very little about RF. I have 2 questions if you experts can help me. I have on RF transceiver with 10mW output power and this antenna...
  3. Morcego

    EMC testings

    Thanks Dbaird and micalbrch. 300+ Labs in Europe alone!! I have to type a lot... M.
  4. Morcego

    EMC testings

    Hello, I'm completly new to CE mark.My company is located in Europe, and I produce several electronic equipment, with maximum supply voltage of 24V DC. It falls under the EMC directive only, so I was told. My questions: Can I test my equipments in a non notified body, and do a self...
  5. Morcego

    RS485 Biasing

    Hi All Terminating, biasing and add a ground reference solve completly the problems on my network. The switching power supplies are isolated, so I completly lost my reference (normally given by earth wire). Biasing was also important because the network was picking some noise. I have learn a...
  6. Morcego

    Schematic Capture Software

    Eagle as lots of libraries. Thats the best is this package. But you can import them to diptrace easy. (if you dont care about copyrights :) Also don't trust Eagle's DRC at 100%. I had to trash some boards a while ago. DRC works, but if you change the board a lot and mix manual and automatic...
  7. Morcego

    RS485 Biasing

    Thanks all for the awnsers. Tomorrow I will implement this solution and post the results.
  8. Morcego

    Schematic Capture Software

    Hi, Check out diptrace also (www.diptrace.com). They have a new version with a good autorouter. Also cheap like eagle. Very easy to learn. Joaquim
  9. Morcego

    RS485 Biasing

    Thanks for the awnsers. @Keith The 620 ohm resistors are connected bettewen "A" and Vcc (one) and B and GND (the other). Because when the line is in idle mode (no transmit) is at unknow state. The 2 resistors are bias to make sure the line is at "mark" state. I have read something about this...
  10. Morcego

    RS485 Biasing

    Hi experts, I have the following RS485 network setup (2400bps): Slave1 ---1.5Km----Master---300m---Slave2 I know that I must use 120 terminating resistors at both ends. No problem, because the boards have jumpers that can select the terminators. But I must use bias as well (620 ohm resistor...
  11. Morcego

    Advice on filtering / regenerating digital signals

    Well, the prototype is running at a factory floor because is to large fr my small lab :) In the factory floor we have some large metal working machines... Maybe they are the source of noise... The RS485 approach is a good one. Small processor for each board (addressable) and a master controller...
  12. Morcego

    Advice on filtering / regenerating digital signals

    Separate grounds are not possible. I use constant current drivers that use same common ground for logic and power. The only difference is Vcc (5v for logic) and VLED (12V for LEDS). In my prototype sometimes I have one missing pulse causing the matrix to show the chars incorrectly. I had check...
  13. Morcego

    Advice on filtering / regenerating digital signals

    Hi, I'm designing a LED matrix for Outdoor VMS of a considerable size (about 5meters). There are about 16 matrix. From matrix to matrix are traveling signals, like clock, data out, latch enable etc. What is the best circuit to amplify / regenerate signals? And about noise filtering (I did see...
  14. Morcego

    Power supply problem / PWM

    I did what Rodrigo suggested and the problem was less evident... The large capacitor at the end of the power supply leads (at the input terminal of the 7805) solve the problem. Also I have increased the value of the capacitor at the ouput. Now I have a clean VCC at any duty cycle. Learning...
  15. Morcego

    Power supply problem / PWM

    Hi All, I have a problem using (what I considered) a simple circuit. I use a microcontroller that generates a PWM signal that feeds a gate of a N-channel Logic level MOSFET. When I switch the LOAD on and off (without PWM) the 5V (that powers the micro) is perfectly stable. When I use PWM to...
  16. Morcego

    Doppler Radar Sensor

    Thanks guys. I had no Idea of the cost of such a unit. The price was imposed by the costumer.. 200 kph limit is teorical.. In fact the purpose is to fire up warning lights everytime a car passes at more than 140 kph (Highway legal limit in my country). I know that a 35$ and 59$ units seems in...
  17. Morcego

    Doppler Radar Sensor

    Hi, 1st, please excuse me if this is on the wrong forum. I need speed detector to a costumer of mine. It needs to detect cars moving at speeds up to 200kmH in a highway. I had found some im the market like Falcon-LC, but it costs about 500USD. Can anyone point me to a cheaper solution? It...
  18. Morcego

    Help on designing a LED circuit

    Thanks guys for all the answers. I will try first the easy one as Keith and Scotty suggested. But my micro only as 4 pwm channels and I need 12. I don't know if I can implemented them in software. The other suggestions; AND gates and PWM the entire power source (except for the micro power supply...
  19. Morcego

    Help on designing a LED circuit

    Dan, Do you mean connecting all the sources of the panels MOSFET's to the drain of the PWM MOSFET and the drain of this one to the ground (keeping the positve side of the panels allways connected to the 24V)? This was my original ideia, but I'm not sure if it works correctly. TIA M.
  20. Morcego

    Help on designing a LED circuit

    Hi, Yes I will use a micro. I know that I can turn them ALL off by putting the PWM to zero. I need to have INDIVIDUAL on/off control of each panel. That's my problem. This is for led (panel) arrows in a highway curve, The arrows will turn in sequence one after the other to alert the driver that...

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