Search results

  1. T

    .4 V DC to 5 V DC possible?

    zach48191, So you plan to use an LM34 temperature sensor, and need to use its output to switch your relay at a particular temperature? If this is true, you do not need the LTC3108 at all. It is a neat part, but does not do what you want. If you are building the LED thermometer...
  2. T

    I Have a Board That I Need Produced...

    Mike, I realize this does not answer the question you are asking, but have you breadboarded this circuit and verified that it does what you want? I am having some difficulty seeing how it could do anything useful. And do you know about the NE556? As for producing a few copies for...
  3. T

    4017s lighting up 60 LEDs sequentially

    lpsarsam, I'm not sure that regular logic ICs are your best bet. There are alternatives. Regular CMOS logic parts, such as the CD4017 have pretty weak output pins; your LEDs may want more current than the rated output current for such parts. Don't forget that you will need to limit...
  4. T

    Digital Logic Gates

    vick5821, The terms "active high" / "active low" are used to relate the voltage state at a given point in a physical circuit to the associated Boolean, or binary, logic value, often termed "true / false" or "1 / 0". A "high" signal is the more positive of the possible signal voltages...
  5. T

    Is this the 'Tip & Ring' of the telephone system?

    FoTonics, You failed to reveal your location, which matters in this case. Your colors appear to be Bell System standard, where red and green are used first, and yellow and black are spares, or used for a second line. I don't think they had Bell in Australia; Mr. Mitchell's colors...
  6. T

    How to design a 30V DC to 200-300V DC (adjustable) inverter ??

    Samarth, I'm sure there is more good info out there, but I quickly found this LT AN: http://cds.linear.com/docs/Application%20Note/an118fa.pdf The late Jim Williams in action, complete with photographic 'scope screen shots. He is addressing what looks like exactly your application...
  7. T

    How to design a 30V DC to 200-300V DC (adjustable) inverter ??

    Samarth, I think the basic E & I information you need is in the data sheet. This is an avalanche device, so it must be biased near the breakdown voltage in order to obtain the rated sensitivity. I found the following in the linked data sheet: Note that a specific value of VR is...
  8. T

    How does the transistor work in this circuit?

    goodanna, I think the previous answers have made clear why the transistor is necessary. I question whether the transistor is sufficient. Nowhere do I see mentioned any specs for the solenoid. Do you have any? Particularly, we need to know the DC coil resistance. Even with the...
  9. T

    I/O Expansion Of 16f877a

    kasuncharya, Have you considered using a second PIC microcontroller to provide the extra I/O you require? Either another PIC18F877A, or another from the same family. The PICs can talk to each other using the I2C or SPI bus. It is possible your project might benefit from having a second...
  10. T

    Help with Voltage amplifier (mV)

    rtronic, I agree with the previous posts. We need your schematic, in order to be of much help to you. ( Specifically, the schematic of the circuit being simulated.) The cautions about the limitations of the 741 and power supplies are on the mark. Do you know your way around the...
  11. T

    Confused about circuit and shift register

    Woodworker82, Glad you are making progress. It's hard to work without a 'scope. If you are going to do much of this, try to find one you can beg or borrow. Or a PC based module might be a good bet for you. ( If you have a second PC to use!) Remember, with the '194 shift register...
  12. T

    Confused about circuit and shift register

    Some quick thoughts about this project: The parallel printer port ( "Centronics"), uses TTL logic levels. Newer ones may put out 5V CMOS logic levels, which still work well with the older TTL parts. There is nothing RS232 about this port. Woodworker82 is creating a serial bit stream in...
  13. T

    Electrolytic Capacitors

    Sanjaya, I believe that many CRT monitor / TV sweep circuits use an electrolytic capacitor that is worked very hard. The factory part often fails, even though it is a special type. If the capacitor you must replace is larger than others with similar capacitance and voltage ratings, then...
  14. T

    Ideal Transistor for battery discharger

    rooster92, Re the hot FETs. You need to decide how the circuit should function as the cutoff voltage is approached, then modify the LM324 circuit to either shut down quickly and completely, or to control the load current as it tapers down, without oscillating. In the second case...
  15. T

    LM317 circuit

    Plague, We all try to be of help. Just let us know how the project turns out. The diode should lase at currents between the threshold and the max operating current. If the current is far enough below the threshold, I believe the diode will still produce light, but the output will not...
  16. T

    Ideal Transistor for battery discharger

    Rooster92, I concur with the previous posts pointing out the lack of base drive for the power transistor in your original circuit. There are quite a few more potential problems. I'll try to add to what the previous posts have said. Can you reveal the identity of your op-amp? Looks as...
  17. T

    Creating a 12x3 digit 7-segment display with Arduino

    Panici, I'll try to respond to your comments: Yes, it would be nice to not have giant arrays of resistors. Even a giant array would have to be wired-up. Perhaps you enjoy wiring, but I think there will still be enough work, even if the design is optimized to minimize the number of...
  18. T

    Creating a 12x3 digit 7-segment display with Arduino

    Panici, I'm not sure that something like the 74HC595 is a good solution. The outputs are stout enough to drive a single, un-multiplexed segment, but will require a current limiting resistor to interface to the display. Without multiplexing, you will need 36 of these ICs, and nearly 300...
  19. T

    Logic gate input from comparator

    Matt, The doctronics circuit looks as if it should work. Perhaps you have a simulation problem. Many simulators have ways to set-up initial conditions, you might look into that. It's possible the cap is not starting out at zero volts. You might try adding a resistor between pin 6 ( the...
  20. T

    Night causes buzzing

    Bluestribute, Is that light on a triac dimmer? That might cause some buzzing. Also, if the electrician wired the light neutral wire to the outlet safety ground, that could cause hum trouble. Are the outlets in question grounded, i.e. three pin? And what electrical code is in...
Top