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  1. dorke

    Vhf radio tx issue

    1. Make sure that the battery connection is good and firm. 2. Make sure the antenna connection is good ,clean(no rust etc.) and firm. 3. If it doesn't complain about the antenna,it could be a faulty unit ,I would contact Cobra technical support.
  2. dorke

    Galvanic Isolation in Series? Do they stack?

    Not clear what you are trying to do. Are you talking about mains isolation? Here is some reading material and here is another for you.
  3. dorke

    Broke Cathode Ray TV

    o.k Take care and be well.
  4. dorke

    Vhf radio tx issue

    It should work. Take into account that there are actually 3 items: Transceiver,Antenna and the coax connecting them. The marine VHF is a very narrow band 156-162MHz , so the antenna doesn't need any special tuning. The ammeter movement doesn't mean much. Even without an SWR meter. Use the...
  5. dorke

    Broke Cathode Ray TV

    The hissing sound could be the air coming into the vacuum tube(assuming it was a crack and not shuttered to pieces ) You can read about the materials a CRT is made of here. If you don't have any nausea,vomiting,diarrhea or throat and stomach pain then it is probably nothing . If in doubt...
  6. dorke

    Galvanic Isolation in Series? Do they stack?

    Welcome to EP. I think not. It is like a chain composed of links,it is as strong as the weakest link right? If the 9KV is subdued what good is the 1KV one for? Please give more details
  7. dorke

    Suggestions for auto plug disconnection and protection

    It would be very strange if you find one. Have you ever seen a car yank the fueling hose in a gasoline station? I have,not a pretty site:eek:
  8. dorke

    New Guy Here Need Help -SOLVED!- identifying negative lead of these old Nichicon electrolytic caps.

    Yes it would,get a NP type. You see the NPs are audio grade, while the polarized ones are DC grade(good for very low line frequency filtering).
  9. dorke

    FPGA

    Looks like it doesn't have a USB on board programmer. There are 7 different ways to program it on-board and of-board It means you can program it with a dedicated programmer or it can boot from an on-board device. What do you mean by "have to buy an FPGA"? What are the needs and requirements? Do...
  10. dorke

    Suggestions for auto plug disconnection and protection

    Two simple solutions: 1.Prevent it from "brushing against the road". 2.Make sure you disconnect it properly before the "vehicle drives away".
  11. dorke

    New Guy Here Need Help -SOLVED!- identifying negative lead of these old Nichicon electrolytic caps.

    Sure there isn't. This cap is an Electrolytic NP(marked on it). NP stands for No Polarity, they are often used in audio circuits and speaker crossovers.
  12. dorke

    Solvent to clean solder site

    Please post a clear photo. Sometimes what is actually left is just a burn circle were there used to be a pad:(
  13. dorke

    How can I design a multidrop connection for TTL serial communication?

    What you need is a multi-master or "multi point interface". You need to define the working speed and distance that the connection requires. Apart from the RS485 that Harald suggested. You can use I2C ,SPI and even Ethernet or wifi. All of them require a protocol.
  14. dorke

    Osillascopes?

    I agree . The scope has a "grounded reference". That is true for all measurements with a scope. To perform a true differential measurement we need to use 2 channels and use the "subtract feature " of the scope. Measuring mains with a scope would require an isolation transformer,or an...
  15. dorke

    Linear Power Supply Help!!!!

    Yes, more accurately put: off the unregulated voltages.
  16. dorke

    Osillascopes?

    My pleasure. You are correct about the diodes.
  17. dorke

    Linear Power Supply Help!!!!

    You can as Harald showed you but the 7805 will disipate a lot of heat. You should use the 317 and 337 in the same way as the others, it has nothing to do with the use of the 7905.
  18. dorke

    Osillascopes?

    The Zeitnitz scope is fine there is a 1.46 version of it. The "tiny voltage level spectrum" is not a problem at all, you need to use a simple voltage divider to overcome this. probe /attenuator and a DC block explained: The input to a PC sound card should be limited to no more than about...
  19. dorke

    Low Voltage Disconnect 12V for NiMH battery 7.2V

    Welcome to EP. That Low Voltage Disconnect will not work , it's spec is far from what you need. But, you can make a DIY circuit that will do what you need.
  20. dorke

    Osillascopes?

    For Audio measurements the Software Scope is a great free scope. True ,it has no reference. It needs to be calibrated,that can be easily done withe a known audio signal level. It also needs some kind of a proper probe /attenuator and a DC block. Which software scope have you seen?
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