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  1. KrisBlueNZ

    Using $1 stereo amp in mono mode

    100Ω is lower than 10 kΩ. I recommend that value because there will be less signal attenuation. That's the main reason.
  2. KrisBlueNZ

    What is your favourite type of component?

    True that. The resistor is a pretty boring component, but we'd all be in big trouble if they didn't exist! And they are actually pretty impressive technology - a little metal film resistor that costs a fraction of a cent is impressively close to a perfect or ideal component. But still, I think...
  3. KrisBlueNZ

    How to move up/down the frequency wavelength

    You seem to have forgotten to tell us what you want to move up and down the frequency range. Are you trying to receive RF signals at different frequencies?
  4. KrisBlueNZ

    Different Voltages to Same Load...?

    First, I assume your +24V and +12V markings are supposed to be on the anodes (left sides) of the diodes. It doesn't make sense for them to be on the cathodes, because the cathodes are connected together and therefore can't be at different voltages. If that's the case, then the higher voltage...
  5. KrisBlueNZ

    Using $1 stereo amp in mono mode

    It will reduce the volume a tiny bit. But you shouldn't tie the left and right headphone output signals together directly. It's not likely to do any harm but it might increase distortion.
  6. KrisBlueNZ

    Using $1 stereo amp in mono mode

    Right, that was only so I could tell you how to link both channels together, but that's obvious - just connect the L and R inputs together and feed them from a mono source. To convert a stereo headphone output to mono, just feed each signal through a resistor of around 100Ω to a common point and...
  7. KrisBlueNZ

    Using $1 stereo amp in mono mode

    Good! Speaker drivers never sound very good without some kind of enclosure.
  8. KrisBlueNZ

    What is your favourite type of component?

    My favourite component is the 555 timer! Just kidding. I just said that to p*ss Adam off! I agree with Steve on the 40106 or the 4093. Very versatile devices. Also I think modern MOSFETs are pretty amazing with their ON-resistance into the low milliohms, and I think microcontrollers are...
  9. KrisBlueNZ

    Need help with electronic circuit (Make: Electronics Experiment 8)

    Great! That circuit will never flash the two LEDs evenly, but you can lengthen the duration of the flash on D1. Replace the link that goes from D1 to the relay coil and the positive side of C1 with a resistor of about 100Ω.
  10. KrisBlueNZ

    Interference in video switching circuitry

    Yes, those devices are designed for video switching. The CMOS 4000 series devices have too much capacitance and aren't designed for those frequencies.
  11. KrisBlueNZ

    Constant voltage load

    I honestly don't know! Yeah, I guess that would make it more likely to become unstable. And mess with the circuit to see how quickly it stabilises when it's returned to normal, and whether there's any overshoot or ringing, I suppose. MPPT interests me. Will you be posting your design here?
  12. KrisBlueNZ

    How to step down high-current negative DC voltage

    As I said, I would use a switching supply with synchronous rectification. Have a look on Digi-Key - they have a huge selection, all parameterised and ready to choose from, with links to data sheets. You haven't gone into much detail, but one method that comes to mind would be to combine the...
  13. KrisBlueNZ

    How to step down high-current negative DC voltage

    How are you planning on switching the current? How about generating a single 1V supply and reversing the polarity to the electromagnets using an H-bridge?
  14. KrisBlueNZ

    How to step down high-current negative DC voltage

    You'll definitely need to use a switching converter of some kind. Low-voltage output with high efficiency normally means a synchronous rectifier, but I don't know of any synchronous controllers that are able to work as negative regulators. Is it really essential that the positive side of your...
  15. KrisBlueNZ

    Week 9/11 Progress(?)

    Right, if you can't tin the tip, you won't get anywhere at all. It can be cleaned, but start gentle, because if it's a good quality tip, it will be plated, and you don't want to scratch the plating off. Work on one area, in case you scratch it. When the iron is completely cold, start with a rag...
  16. KrisBlueNZ

    Week 9/11 Progress(?)

    Are you using tin/lead solder? Or lead-free? Can you tin the tip of the iron? Is the iron temperture-controlled? If so, what temperature is it set at? If not, what wattage is it? Upload some photos, or if you have a YouTube channel, put a video there and link to it.
  17. KrisBlueNZ

    Constant voltage load

    Hey Steve, My only concern, and one I can't quantify, is that the circuit will have a very steep V-I curve above the threshold voltage of 11.8V. In other words, almost zero dynamic resistance. The TL431 has a very low AC output impedance, then you're amplifying it with a common emitter...
  18. KrisBlueNZ

    Need help with H-bridge circuit running printer motor

    Hi there and welcome to Electronics Point :) As is common with electronics-related articles on instructables.com, the author of the instructable is a beginner himself and doesn't fully understand the circuit. There are many minor and some major errors in the article. If you copied the...
  19. KrisBlueNZ

    a timing circuit

    Sorry Joseph, but neither those photos, nor that construction method, is acceptable. You need to build the circuit up on a piece of stripboard like this: http://www.digikey.com/product-detail/en/8022/V2018-ND/565947 While you're doing that, you can remove the 100 kΩ resistor - it doesn't do...
  20. KrisBlueNZ

    Need help with electronic circuit (Make: Electronics Experiment 8)

    Your relay has a non-standard pinout, different from the relay used for that breadboard layout drawing. On your relay, the changeover contact (which connects to the pushbutton) is on the third pin down, and the normally closed contact is on the second pin down. So you have to swap the...
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