Search results

Search Forums New Posts
  1. AnalogKid

    Two transistors to switch on/off two relays with an arduino from one pin

    There is a flaw in your logic. There also is a flaw in the schematic, but not in the way you think. At least one relay should come on. A better way is to have pin D3 drive two resistors, one for each base. The problem is that the base-emitter forward voltage is not exactly the same for all...
  2. AnalogKid

    Decibel Calculation

    As above, your equation has an extra term in it (0.43429). It might be a conversion factor related to wherever the equation came from, but without more information there is no way to know. Is this homework? ak
  3. AnalogKid

    9v Guitar Amp w/out LM386

    The output coupling capacitor is calculated from the speaker impedance and the lowest frequency you want in the flat passband range. C = 1 / (2 pi f R). 8 ohms and 100 Hz works out to 200 uF. The power supply filter cap wants to be at least as large. Whatever the output power is, around 40%...
  4. AnalogKid

    9v Guitar Amp w/out LM386

    Not sure "need" is the right term, but ... I've seen three kinds of distortion mechanisms for guitar effects: Diode clipping - sharp transition corners, lotsa high freq harmonics Overdrive - soft transition corners for a fat sound without the harshness Crossover - some people just like it...
  5. AnalogKid

    bleeders and what I am doing....

    1. I don't see a question in there. 2. Open the browser history (Ctrl-H) to see past websites. ak
  6. AnalogKid

    9v Guitar Amp w/out LM386

    Are all integrated circuits banned, or only the LM386? There is a variation of an opamp output current booster that is more efficient than the 386 or the circuits posted. ak
  7. AnalogKid

    9v Guitar Amp w/out LM386

    No, it isn't. *Your* head is fine. ak
  8. AnalogKid

    9v Guitar Amp w/out LM386

    0 for 2. First, they do *not* "cause more resistance". Second, if they did, that resistance would be in the voltage amplifier collector and *increase* the "amplification". Do you know why the diodes are in the circuit? What dressing goes best with word salad? ak
  9. AnalogKid

    Ball wall target board

    A peak detector circuit per sensor would capture the peak signal voltage associated with the initial impact in real time, then hold it for the controller to come along and read. The multiple detector circuit outputs can be threshold-detected and OR-ed to form a single trigger signal to tell the...
  10. AnalogKid

    Wireless relay

    ebay has many wireless remote control systems that have a small transmitter (a pc board assembly or a key fob) and a receiver board with a relay output, some under $10. Controller 240 Vac powers a wall wart that powers the transmitter. Receiver needs a wall wart for power, relay controls the...
  11. AnalogKid

    Quiz buzzer system

    Making up the connecting cables is a pain. Another option is to buy them. Audio extension cables are cheap on ebay. This changes the connectors on the controller; use whatever matches the cables. On the other end, cut off the connector and solder the wires directly to the switch...
  12. AnalogKid

    Quiz buzzer system

    Here is an expanded version of the minimal circuit, with connectors to plug in the contestant boxes and a beeper that chirps when a response is latched. The plugs and jacks for the cables can be anything. 1/4" phone plugs are larger than necessary, but easy to install. The large capacitor C2...
  13. AnalogKid

    Quiz buzzer system

    L.I.K.E.!.!.!
  14. AnalogKid

    Quiz buzzer system

    A better and more reliable arrangement is to have only the buttons at the contestants locations, and put all of the lights, electronics, and buzzer in the control box at the moderator's desk. In this way the contestant boxes have nothing but a switch, and only two wires going to each. Two-wire...
  15. AnalogKid

    Help with a Simple Electronic Timer

    That is called chip-on-board. It is an IC silicon chip without the package and pins. Very low cost for very high quantities, almost always a custom chip from China. Your circuit has one resistor, one capacitor, and one tuning fork "crystal". A $4 lamp timer from Wal-Mart will do everything...
  16. AnalogKid

    Time Counter From Manual Pulses

    The 60 minutes part is a given. Do you want the hours section to roll over at 23 hours or 99 hours? ak
  17. AnalogKid

    Time Counter From Manual Pulses

    So it is a simple 4-digit counter that increments one count whenever the input is toggled, with the modification that has it count modulo-60 and modulo-24. Yes? ak
  18. AnalogKid

    Time Counter From Manual Pulses

    Any digital clock circuit is a time counter. Your operating description in post #1 is not at all clear, but if you want a timer to be enabled/disabled by an external circuit or switch, that is not a difficult modification to any clock or stopwatch circuit. Is the intent to accumulate the total...
  19. AnalogKid

    Active narrow band-pass filter design

    Agree with AG, separate highpass and lowpass circuits in series will get you much better performance. However, going beyond two poles for each one will require some very precise components, particularly capacitors, and these are expensive. As a next step, look into two-pole highpass and...
  20. AnalogKid

    Interfering circuits

    There is no decoupling of anything anywhere. There is no indication of how grounding is handled among the circuit elements. There is no coupling capacitor between the first and second opamp. Left amp offset voltage could drive right amp near or into saturation at high gain, giving chaotic...
Top