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  1. S

    8255A or Mc6821???

    Check the data sheets on the devices.
  2. S

    Sony DVP-NS700P DVD Player Turns On Then Turns Off

    Bending the board and seeing a change in operation would indicate to me a bad solder joint (since you checked the trace). Use a magnifying glass or a loupe, resolder any questionable connections. I'm hearing a lot of problems lately with cold solder joints. This RoHS (lead-free) solder is...
  3. S

    What 220V AC plug is this?

    They look like High Frequency connectors. What's the name of your equipment manufacturer, and model number. You should be able to google the equipment and find exactly what you need. (I don't recognize them. The ones on the right MIGHT be SMA connectors, but I can't tell for sure.
  4. S

    Altenatives to soldering

    When you get your breadboard, you're going to find you want to start getting parts to experiment with. Radio Shack is kind of pricey for parts. Start looking around your neighborhood for electronic component supply stores. You're going to want to know where they're at pretty soon.
  5. S

    Altenatives to soldering

    How about this? Solderless breadboards. They're relatively cheap these days. It's not a permanent circuit. But it'd be good for experimenters. Radio Shack still sells 'em, with hook-up wire kits. Manufacturer's are Elenco, Global, and Twin. Google the term electronic breadboards, or the...
  6. S

    Pinball Flipper Logic

    I don't have your pinball machine. MY pinball machine is wired so that the lower flippers STAY up when depressed, and the upper flippers are wired to flip ONLY when the button is depressed, and then it deliberately releases. I assumed it was deliberately designed that way as a challenge to...
  7. S

    Altenatives to soldering

    I don't know what else to tell him. Of COURSE the emergency solder isn't the best solution. (Maybe I shouldn't even have mentioned it) If his dad is dead-set against an iron. I'd go with wire-wrap. Maybe I'm just to old, and it's time-consuming, and the tools and supplies for it are not used...
  8. S

    Unexpected signal in circuit.

    If you're not in the U.S., it sure sounds like it's AC from your 50Hz wall socket.
  9. S

    Altenatives to soldering

    If your dad lets you play with matches they make flat ribbons of solder that are sold for emergency type repairs. It has a very low melting point. I used to buy it from Radio Shack but I don't know if they carry it anymore.
  10. S

    VARIABLE RESISTOR PINOUT

    Just trivia: There are linear pots, constant resistance across the carbon track, and Audio pots, which have logrithmic resistance.
  11. S

    Altenatives to soldering

    It depends on the application. What IS your application? If it's electronics, you have to be very careful. Soldering uses heat to connect devices to circuits. If you use some other method to connect an electronic device to a circuit, you have to be careful to not damage the electronic...
  12. S

    Bridge Rectifier help

    First. Is your bridge JUST a bridge, or is it a module that has other components in it? A bridge rectifier is indeed 4 diodes wired in a bridge configuration, so you can do that. (I don't know why though, you can get a replacement bridge at 3A for less than $5) Do you have a part number on...
  13. S

    Currents in Circuits.

    I really oversimplified it. In circuit theory and practical application, one of your most valuable tools, is reliably knowing your current. It tells you which devices to use in your designs. As a repair tech, the biggest issue I find is circuit damage due to excessive current through a...
  14. S

    Instrumentation Amplifier for ECG

    I appreciate you don't need precision. What you DO need, is sensitivity. Good luck with the experiment.
  15. S

    Instrumentation Amplifier for ECG

    I read your 'guy' article. His observations are as a learning experiementor. The only thing he said at the end of his article that caught my attention was his claim that you need a more robust amp. He should have said a device with tighter specs. His device for measuring heartbeats CAN'T...
  16. S

    Instrumentation Amplifier for ECG

    I quoted myself. There are several types of instrumentation amps. In most cases they're glorified op amps. Op amps are generally pretty cheap (like your LM741's). You design tighter specs and you market them as 'instrumentation amplifiers'. That way the customer doesn't feel so bad about...
  17. S

    Broken Car Amp

    The TIP2955 & TIP3055 is complementary (one PNP, other NPN). I pulled a TIP3055 out of my parts box. I read: Base to Collector 1.86M Ohms one way, virtual open the other way Base to Emitter 1.94M Ohms one way, virtual open the other way (back to back reads) (It's a TO-218 pkg by the way...
  18. S

    Reference book

    I agree. Or even ebay or amazon.
  19. S

    Instrumentation Amplifier for ECG

    I think you're on the right track scouting the internet for ideas. In answer to your second question, the output is a characteristic of an instrumentation amplifier (Operational Amplifier). It's stated: 'The output is inverted from the input signal'. That's the effect of an Op Amp. Maybe...
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