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  1. C

    What happens if you connect 2 isolated power supplies backwards?

    No problems connecting two supplies backwards - but in series. I recommend it all the time. If one is 1amp and the other 500mA, you can only draw up to 500mA. And the voltage will be the difference between the two. The same applies when connected in series. The max current is 500mA and the...
  2. C

    Need replacement capacitor but value not readable

    I would start with 100n X2 capacitor. (104)
  3. C

    Markings on analog moving coil meters...

    A meter that consists of a coil and pointer is called a MOVEMENT. And it has a certain sensitivity. Generally the sensitivity is 30uA or 10uA. For a movement with a sensitivity of 30uA, it will take 30 microamps to defect the pointer full scale. At this stage you cannot use the term OHMS PER...
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    Best soldering technique to prevent component heating?

    In my article on soldering I mention a few new points. Firstly, the solder bought from China is not 60/40 It does not melt. It does not run. It does not produce a shiny joint and it produces a shocking result. DO NOT USE IT. Secondly, there are two techniques to soldering. One is to select...
  5. C

    Building a device from a schematic (Yet another work in progress)

    None of the xIMGx are appearing. Not allowing brackets in answer.
  6. C

    Led problems

    The article contains so many mistakes that I would NEVER recommend it. Take for example this diagram:
  7. C

    Led problems

    Would this be of any help? To start with, a LED does not have a positive and negative lead. It has a cathode lead and it is marked with a (k).
  8. C

    SAFE Regulated Power Supply

    Buy a 12v car battery.
  9. C

    Transistor amplifier configuration for transmitter antenna

    You have to show the circuit before we can even start to comment.
  10. C

    Easy Machine To Wind Transformer

    If you are winding on a bobbin with sides, there are few problems. If you winding on a core with insulation between the layers, the problem comes when finishing a layer. The wire will fall off the end and get wound around the machine. Then all the turns will come off the layer. Also thick wire...
  11. C

    Easy Machine To Wind Transformer

    It is best to hand wind the turns because you can then maintain the correct tension. You can buy a counter from a toy shop for a few dollars. Or keep count. Unless you are an absolute expert, a coil winding machine will drive you insane.
  12. C

    What's wrong with circuit?

    You set the whole circuit up with an isolation transformer Connect a 3 watt night-light as the load Now short between base and emitter and the lamp should turn ON. Now
  13. C

    What's wrong with circuit?

    "Well, that's what my fluke meter tells me." It's a FLUKE they work at all. You have to remember, when there is a high frequency in a circuit, these high impedance meters do not work at all. A TV technician came to me 40 years ago and said there was positive on the grid of the 6CM5 valve via...
  14. C

    What's wrong with circuit?

    You can't have 16.7v across the resistors and 12.7v across the 1k because the transistor is turned ON and all the leads are at the approx same potential.
  15. C

    What's wrong with circuit?

    "A 1N4007 diode is rated for 1000 V PRRV, peak repetitive reverse voltage. It is NOT NOT NOT a zener diode of any kind. " Of course it is a 1,000v zener diode. What do you think it is?????? "In a circuit like this that has no external earth ground reference, it is NOT the case that the N wire...
  16. C

    What's wrong with circuit?

    "I use 3.5mA per 100n for half-wave" This applies for 240v AC. So the voltage will be about 12v to 18v. You have drawn the circuit differently, NOW. The circuit above will BLOW UP.
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    What's wrong with circuit?

    I use 3.5mA per 100n for half-wave The whole circuit works on 50Hz. I don't see how the circuit starts and stops
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    Bench Power Supply?

    "Listen to Colin. He knows everything." I am glad I can add you to my other 22,000,000 visitors to my website who take heed of what I have to say.
  19. C

    What's wrong with circuit?

    The 0.68u will pass about 24mA and charge the 220u. The transistor will be turned on and 24mA will flow through the 1k producing about 24v across it. This is basically the DC conditions of the circuit and the timing (the point at which the transistor turns on) will depend on the effect of the...
  20. C

    What's wrong with circuit?

    I cannot go any further because I cannot read any of the values of resistance.
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