Recent content by rmdrmd

  1. rmdrmd

    Monopole antenna length.

    Thanks to all of you for your assistance on this. I now have a simple antenna on my receiver (based on the advice received) and the effective range of the transmitter has gone up from only 10 meters to around 60 meters. More than adequate for the application. Cheers.
  2. rmdrmd

    Monopole antenna length.

    Thanks Dave. Why did you specifically nominate .96 as the velocity factor?
  3. rmdrmd

    Monopole antenna length.

    I'm after a little help. I want to add a very simple single wire antenna to a radio receiver. Is the correct length for the antenna one quarter of the wavelength? Is it as simple as that? The frequency is 27.145 MHz. From a calculator I see that makes the wavelength to be 11.044 meters. Does...
  4. rmdrmd

    Exam question help please?

    And for the record, the examiner says the answer is the first option: It will turn on.
  5. rmdrmd

    Exam question help please?

    This is an actual question in a test. So I guess you are saying that it is a bad question for a basic electronics class?
  6. rmdrmd

    Exam question help please?

    OK, I will go out on a limb and say that I think that it is a terrible exam question. I have a feeling that it is probably mislabeled. What is marked as the transistor should be marked as a bulb - and what is marked as the bulb should be labeled as a resistor. If mislabeling is not the case then...
  7. rmdrmd

    Exam question help please?

    Would someone like to critique the multiple choice question in the attached image file? I'm looking for discussion about the question itself - and the correct logical answer. I have my own opinion, but would like some independent input please
  8. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    thanks people for all that assistance. I will hunt down an appropriate transformer and get this thing up and running again. very happy to have found this excellent forum. thanks again.
  9. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    The three transformer wires are different - I have marked them in the diagram. The secondary winding does seem intact. (good thinking) Red/yellow to Red = 3.0 Ohms. Red/black to Red = 3.1 Ohms. Red/yellow to Red/black = 0.3 Ohms. The transformer weighs just a touch over 500 grams ( 1lb...
  10. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    So here are images of both sides of the board. Currently living in Australia. Not looking to buy another one running at 110V. Best for me is just to fix this one with a 240V transformer.
  11. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    ok. so here are some photos. as to why did it melt ? look, I think it was probably due to a crappy (poorly regulated) input voltage. see the last image. that is a 240v to 120v converter (electronic) I have been running it through this electronic voltage regulator successfully for nearly two...
  12. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    It plugs into 120 volts AC. 50 - 60 hertz. The unit supplies from 0 to 20 volts DC. Very precisely regulated. Max load is 500 milliamps. There are two wires into the transformer (mains supply), and three wires out (to the circuit board). There are no markings on the circuit board indicating...
  13. rmdrmd

    Power Suppy Transformer viz / rca WP-703A

    The transformer in my constant voltage power supply has melted. it is a VIZ model WP-703A (same as RCA WP-703A). the numbers on the top of the transformer are: 9603-014 and EIA 831 8619. Because it has failed I cannot test the output voltage - I need the output voltage so that I can...
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