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  1. KrisBlueNZ

    Problems with LM1036 amplifier

    Also, compare the voltages on the external capacitor pins between the two channels. A problem on those pins will mess up the DC conditions on the channel. Compare voltages on the following pairs of pins: pin 3 and pin 18 pin 5 and pin 16 pin 6 and pin 15 If there's any significant difference...
  2. KrisBlueNZ

    Capacitor replacement question

    I would also replace all caps of the same brand as any that are bulging or leaking. Make sure the replacements are rated for the same or lower ESR as the originals, and the same or higher ripple current, as well as temperature. Stick with the good quality Japanese brands - Rubycon, Nichicon...
  3. KrisBlueNZ

    Phototransistor question

    Thanks for the clarification. I was wondering the same things that Adam asked. TX and RX mean transmit (or transmitter) (i.e. the LED) and receive (or receiver) (i.e. the phototransistor). For that particular problem, a simple solution is to reduce the value of the emitter resistor. Here's an...
  4. KrisBlueNZ

    EEG to tDCS

    I'm afraid that the moderators and management have decided to close this thread because of the potential dangers involved in feeding current through a human head.
  5. KrisBlueNZ

    Alarm reset timer

    Hi again Mark. That circuit uses a simple resistor-capacitor delay. These can have problems with longer time periods because of leakage current in the capacitor. You can try increasing C3 from 22 µF to 47 µF or more but this may not be reliable. You can maximise your chances by using a good...
  6. KrisBlueNZ

    Need help determining components for a circuit.

    I think I've seen two yellow stripes on some germanium diodes. I don't know what they signify (apart from marking the cathode end). 1N44, perhaps? If the stripes are yellow, brown, yellow, grey, then yes, it's a 1N4148. Can't say one way or another without a picture.
  7. KrisBlueNZ

    electronic level

    Cool :-)
  8. KrisBlueNZ

    Next/previous switching a multiplexer

    OK, here's what I suggest for activity monitoring with a single indicator that's ON and blinks OFF for activity on the selected channel, and OFF and blinks ON for activity on the un-selected channels. The MIDI receiver is standard and feeds MIDI data from H11L1 pin 4 to the 4067 data mux...
  9. KrisBlueNZ

    Next/previous switching a multiplexer

    Yes. A "receiver" is an optocoupler and related components. It provides electrical isolation, which is needed to prevent earth loops. Every time a MIDI signal is passed from one piece of equipment to another, it must be transmitted on a pair of wires, normally using the DIN-5-180 connectors...
  10. KrisBlueNZ

    Designing a Time Delayed Relay

    Not that I can explain easily :-(
  11. KrisBlueNZ

    Simple relay circuit help

    It depends how (and how much) you want to learn. To do those calculations for this circuit, you need a basic understanding of how a transistor operates - in terms of how it is controlled, and what its current gain means - and you need to understand voltage, current and resistance, and how they...
  12. KrisBlueNZ

    Simple relay circuit help

    Here's a simple and common way to do what you want. Q2 drives the relay coil. R3 provides base bias to turn Q2 ON. D1 is needed to protect Q2 against the "back EMF" generated by the relay coil when Q2 turns OFF. When a positive voltage (more than about 2.5~3.0V with these component values) is...
  13. KrisBlueNZ

    Multisim Guitar Pedal Help!

    I Googled that error message and got several hits. One of them suggested using the convergence assistant, and listed some possible causes.
  14. KrisBlueNZ

    Designing a Time Delayed Relay

    I can't help with the Eagle problem. They have a forum on their web site don't they? No, the voltage on the LED is 24V. The Everlight MV5053 is a 5 mm red LED, rated for 100 mA maximum continuous current. http://www.digikey.com/product-detail/en/MV5053/1080-1099-ND/2675590
  15. KrisBlueNZ

    Need help determining components for a circuit.

    The image you linked to can't be viewed. imgur says it "cannot be displayed because it has errors".
  16. KrisBlueNZ

    Multisim Guitar Pedal Help!

    What error does it report? There's nothing inherently wrong with that circuit.
  17. KrisBlueNZ

    help needed for engineering college project

    The current drawn from the mains is not limited by the DC resistance of the primary; it's limited by the inductive reactance. XL = 2 pi f L.
  18. KrisBlueNZ

    simple radio building

    Google how does a crystal set work? No. The signal level there is a lot lower.
  19. KrisBlueNZ

    electronic level

    I don't know, but I know how to find out... http://lmgtfy.com/?q=how+does+an+electronic+level+work%3F
  20. KrisBlueNZ

    simple radio building

    As Bob says, R2 is needed to bias TR2 into its linear region so it can amplify. If you remove it, you will probably get no sound at all, or possibly very weak and distorted sound, depending on how leaky the transistor is. Yes this circuit will receive short wave transmissions. Connect the...
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