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  1. (*steve*)

    RGB leds color changing help...

    Firstly, a fuse should not be required. As long as this led is running at low current (say a max of 20mA) then using pots is possible. If you're using a high power led then it is far less feasible to use pots. Lets assume it is a low power led. First thing is to calculate the fixed resistor...
  2. (*steve*)

    Timer Curcuit

    That looks fine. And function 2 looks like the one you want.
  3. (*steve*)

    Diodes purpose in this circuit?

    Oh, they are drawn as schottky diodes.
  4. (*steve*)

    Diodes purpose in this circuit?

    They champ the input voltage a diode drop above Vcc
  5. (*steve*)

    Functions and requirements of the inverter

    If you don't understand what each of those terms mean then you could google then and develop an understanding. Feel free to post your results here and we can make sure you haven't gone off track anywhere.
  6. (*steve*)

    Getting into hot water

    Aaah, the service person turned up. The board was binned, so I have un-binned it :) The bodge wires appear to be under the conformal coating, so they're a factory mod. It's suggestive of a known issue. Apparently this board costs several times the annual maintenance fee for these units, so...
  7. (*steve*)

    Getting into hot water

    After discussion with a colleague, we think the problem is caused because the clip for the fuse is soldered on one side only leaving the plated through holes to carry the full current. This explains the pattern of heating. The fact that the bodge wires are barely thicker than the fuse wire...
  8. (*steve*)

    mobile phone charger circuit

    Wow, that is an impressively poor design.
  9. (*steve*)

    Timer Curcuit

    For 10 minutes, something based on a counter would be better. I believe there is a link to something of this nature in the long duration timer resource.
  10. (*steve*)

    555 output to transformer failure

    That's one option, but if you google for a dc-dc switch mode boost converter you'll find better circuits.
  11. (*steve*)

    Understand VCO

    The mosfet is the thing made of two disconnected bars (like a capacitor with one side longer than the other). It is under the left op amp and is directly connected to the right op amp. Think of it like a voltage controlled switch.
  12. (*steve*)

    Understand VCO

    Ok, that's a cool circuit, and it is comprised of a few building blocks. The first thing to concentrate on it the left op-amp with a capacitor in the feedback loop. This is an integrator (google it for more information). Basically, the output voltage is proportional to the input voltage and...
  13. (*steve*)

    Understand VCO

    At least I could see the circuit. I'm kinda OK at reading circuit diagrams that aren't multimedia enabled.
  14. (*steve*)

    LM317 2N3055 Variable Circuit Problems

    Another newbie mistake is carving up the heat sink when a better solution is to electrically isolate the resistors from the heat sink. And unless you put each resistor on its own heat sink, you may have to electrical isolate them anyway. With a 10V input voltage your max output voltage will...
  15. (*steve*)

    Understand VCO

    A differential amplifier and a differential in math share all the same similarities that either do with a differential in a car. The role of an op-amp is to provide gain. The real magic in a VCO is the way an input voltage is used to alter the frequency response to a feedback element which...
  16. (*steve*)

    555 output to transformer failure

    Try placing a capacitor between the junction of the two transistors and the first transformer. Reverse biased diodes across the transistors may also help. Choose a capacitor so that the resonant frequency of it and the transformer are equal to the operating frequency of the 555. Alternatively...
  17. (*steve*)

    Understand VCO

    You probably should start with simpler circuits. What is your background with electronics?
  18. (*steve*)

    first post

    Hello and welcome
  19. (*steve*)

    Functions and requirements of the inverter

    I'm not sure I understand what you want. You seem to have the basic points covered. Do you not understand what these mean? Or is it something else?
  20. (*steve*)

    Odd Stencil Soldering Problem

    Actually, reading the above post reminds me that I have seen two distinct viscosities of solder paste. The stuff in large tubs which is made for stencil application seems to be far "thicker" than the stuff designed for pneumatic application (one pad at a time through a nozzle). Could the wrong...
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