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  1. Arouse1973

    oscillator doesn't oscillator as I expect

    I think the self capacitance of your small coil and the frequency of your circuit it is not going to effect the resonant frequency much. The apparent inductance Duke was on about I think is what the test equipment would show because of the effect of the capacitance and Z of the whole circuit. If...
  2. Arouse1973

    timer

    When you say placed on it what do you mean. Thanks Adam
  3. Arouse1973

    oscillator doesn't oscillator as I expect

    Thanks Duke for clearing that up. Cheers Adam
  4. Arouse1973

    Voltage controlled thru opamp playing up?

    Ah that makes sense. So a 50-50 DC your hoping to get 2.5V I guess Thanks Adam
  5. Arouse1973

    Hi, pretty basic question about a simple CMOS TTL circuit

    Hi Jed Something like this might work. OR maybe a three input AND gate with one input pulled high? Cheers Adam
  6. Arouse1973

    Voltage controlled thru opamp playing up?

    Can you explain with your software fix why this caused the buffer to suddenly go up rather than down at 0.9V? Does it do this now? PWM is constant at all voltages? I don't understand this then how does the filter average out different voltages then? Sorry might not be understanding what your...
  7. Arouse1973

    oscillator doesn't oscillator as I expect

    High Duke Oh I thought the capacitance of a coil was effectively across the coil, which is why the coil self oscillates. I thought only when skin effect started to play a part did the magnetic flux distribution in the coil rise to the surface due to eddy currents. Which is why the amount...
  8. Arouse1973

    oscillator doesn't oscillator as I expect

    Surely this is only to improve the measurement side of things. So are you saying that the parasitic capacitance effect the actual inductance of the coil? For the inductance to change surely the flux distribution would need to change. Adam
  9. Arouse1973

    Driving a high-frequency IR emitter

    The SS9018 on has a rating of 50mA I thought you needed 200 or more? You can generally get away with much greater current by pulsing it as you are planning on doing. But you have to be careful you don't over do it as you could still damage the component. You are right about the transistor and...
  10. Arouse1973

    Driving a high-frequency IR emitter

    I would go lower than that say around 10ns. And a fast transistor to switch the IR, now you are going to need to current limit this with say a resistor. this resistor will produce an RC time constant with the capacitance of the device, this needs to be considered also. Adam
  11. Arouse1973

    oscillator doesn't oscillator as I expect

    Glad you are making progress. An inductor will change it inductance as the current distribution changes due to skin effect. But at those frequencies and the small diameter wire you are using I doubt it will change much. It's more likely to be the capacitor. What type of capacitor are you using...
  12. Arouse1973

    Voltage controlled thru opamp playing up?

    So 1253Hz should be equivalent to what 5V out from the last buffer or 0V? Is this a square wave? if not what duty cycle are you using. Can you give me the range of frequencies that you are using to give you a 0-5V out of the last buffer. Adam
  13. Arouse1973

    Driving a high-frequency IR emitter

    That's quite a small pulse 50ns for 5% of 1MHz is that right?
  14. Arouse1973

    LED - Light Intensity vs. Current Relationship

    So is this light traveling down the fibre optic over that distance? Or are you just using the photodiode as is. The response of this device looks like it is worked out assuming you are using a fibre optic cable because it does not reference a surface area.Some IR photo diodes will use a...
  15. Arouse1973

    Opening a hobby electronics store: help needed

    For starters. Some items I would consider, But there are many many more. There are lots of component suppliers like. RS components, Farnell, CPC, Mouser, Digikey. Resistors: metal film and carbon of the common values E24 and E96 series in 1/4W, 1W, 2W, 5W etc. Wire wound resistors Resistor...
  16. Arouse1973

    Opening a hobby electronics store: help needed

    Where are you based.
  17. Arouse1973

    Voltage controlled thru opamp playing up?

    There is nothing to forgive, this is what learning is all about. Can you give me your PWM timings please that produce the averaged d.c? I would like to try something. Even though the fault might be in the software I am still not happy with the hardware arrangement. OMO Adam
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