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  1. Alec_t

    cd4067be

    Post the schematic to give us a clue where a circuit modification might help.
  2. Alec_t

    Special Project with led and motors

    Nice job!
  3. Alec_t

    electronic ckt design

    Any good basic electronics textbook (remember those?) will explain it.
  4. Alec_t

    Need with homemade inverter with tl494

    Your inverter transformer is a step up one. If I've understood you correctly, you will use a 12v 60Ah battery to supply it so as to generate 220V which you are then going to use to power a battery charger for charging a 12V battery? What's the point? :confused::rolleyes:. If this is an...
  5. Alec_t

    Need with homemade inverter with tl494

    Perhaps the transformer is unsuitable. What is its saturation current rating?
  6. Alec_t

    LED lamp isnt working, but want to try fix it!

    Looks like the blue/brown wires from the battery have a nick in them where they cross you forefinger?
  7. Alec_t

    Speaker activated switch/relay

    The linked item in post #2 looks to be a circuit which turns on a LED in response to sound picked up by a mike. Not quite what you want. What power supply do you have available to power your gizmo?
  8. Alec_t

    how do you test klixon

    Are there any markings on the klixon to indicate its ratings?
  9. Alec_t

    Why is there an offset on my oscillator?

    Glad it works for you. The ratio of Rb:Rc affects the offset. Ra (in conjunction with the output impedance of the opamp) primarily enables the amplitude to be tweaked.
  10. Alec_t

    Why is there an offset on my oscillator?

    You can offset/reduce the opamp output levels by adding resistors a,b,c like this :-
  11. Alec_t

    Why is there an offset on my oscillator?

    Try increasing R3, or reducing R1, to reduce the amplitude of the waveforms.
  12. Alec_t

    Why is there an offset on my oscillator?

    The input signal of a TL084 can't be as close to the negative rail as it can to the positive rail, so there will be asymmetry in the output waveforms if the opamp inputs are driven close to the rails.
  13. Alec_t

    LTspice: plotting the integral of a waveform

    I think your problem is that you haven't allowed for the current through the zener. Here's a mod of your sim, with B2 added to monitor the inductor current rather than V1 current. The two curves now coincide.
  14. Alec_t

    Vibrating Metronome Project

    Although a pulse frequency of ~3Hz is doable, do you really need it that fast? For example, would a pulse every three or four paces be sufficient? As for the vibration, perhaps the piezo transducer used in most watches for the beep sound could be simply driven with a single voltage pulse each...
  15. Alec_t

    Special Project with led and motors

    The turntable motor from a microwave cooker would give about the right rotational speed, and have sufficient torque.
  16. Alec_t

    Voltage Rectifier/Regulator Design for Magneto

    I'm guessing the magneto has only one (single-phase) winding for powering the lights, but :- Is the magneto single or multiple phase? Is any part of its winding(s) grounded? How many input connections (including ground) did the original rectifier/regulator have? Does the moped have a battery? Is...
  17. Alec_t

    need help please

    Technical gobbledygook.
  18. Alec_t

    Frequency to Voltage Converter Help

    There are, but for a DIY circuit read up about f-to-v converters. That research will probably throw up references to monostable circuits. Once you have your voltage, read up about how you could use it with a LM3914 chip. Edit: I see from the attachment that you are already aware of monostable use.
  19. Alec_t

    Substitute for MC14049 inverting hex buffer

    I don't recommend that converter circuit. Even though 4 logic gates are parallelled to drive each pair of FET gates, they can provide only limited drive current for charging the gate capacitances. The likelihood is that the (obsolete) FETS will switch on/off relatively slowly, causing the FETS...
  20. Alec_t

    Need help with this circuit.

    It looks like an ancient (and inefficient) design, since nowadays there are ICs which handle the FET driving more elegantly. The transformer is crucial to the success/failure of this circuit. The specified FETS appear to be obsolete. The small circuit at bottom left is for turning the 12V supply...
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