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  1. alfa88

    Schematic to reality conversion

    Source is usually the positive side and Drain the negative. They can be reversed but what I said is conventional. Both MPF102 and 2N4557 look like general purpose FETs. The MPF may be better for RF. I didn't study the 2N5457 specs that hard. For an audio amp either one is good. All you need is a...
  2. alfa88

    Schematic to reality conversion

    You might want to get an Ebay/PayPal account. Lots of stuff from China and Taiwan. You're pretty darn close.
  3. alfa88

    Dummy load for amplifier

    It's very bad practice to run an amp without a load. There are some solid state designs out there that won't tolerate it at all. I should know I have one of them and the output transistors can get pretty pricey.:eek:
  4. alfa88

    Foxhole Radio tuning help. My first circuit!

    Me thinks you're right Ken. I didn't think too hard on that one. Perhaps Mr. Banana will need to experiment with the number of windings. This has piqued my curiosity. Now I wanna make one.:D
  5. alfa88

    Foxhole Radio tuning help. My first circuit!

    If you're in the Bay Area you have a plethora of part sources. Radio Shack for limited selection, Fry's better and Jameco Best. For a crystal radio I'd go with a Germanium diode Jameco has1N270 in stock. As far as the capacitance goes. pF is smaller than uF. Next. Your inductor sounds like it...
  6. alfa88

    Need help with a schematic.

    One problem. Fans use a relatively lot of power. Unless it's a big 9 Volt battery it'll die out in no time. Use remote power. Instead of a fan rotating use 2 fans pointed in opposite directions; one on, one off, toggling. The electronic control is simple.
  7. alfa88

    Schematic to reality conversion

    Mr. Noobz, Hopefully you have a Radioshack nearby or better yet a real electronics store. Ask for a perf board. They are phenolic with 0.1"X 0.1" spaced holes and preferably non clad. Well suited for prototyping. I start with wiring the ground bus, then the power buss finishing with the signal...
  8. alfa88

    Safest way to switch 240VAC

    Just as I stated before. The transfer switch (relay coil) is powered up with the utility's AC. If that power goes out it will isolate your generation from the grid. At the same time your generation will be connect to you and only you..
  9. alfa88

    Idiotic statements from Engineers!

    Not a quote but after watching them troubleshoot a while I plugged it in.
  10. alfa88

    Safest way to switch 240VAC

    Transfer Switch What you need is a transfer switch. Basically it is a relay with the coil connected to the utility's mains. If power goes out contacts drop to feed in alternate source (generator, UPS). Now here's a scenario where you don't want to connect a generator straight in. Suppose a...
  11. alfa88

    For Sale: Karma thread.

    Yahoo Mahalo, Gary:D
  12. alfa88

    figuring out an amp circuit.

    Good stuff. The cap is a bypass capacitor. It's supposed to reduce that hum you hear. You might want to look for caps that may have gassed. Signs are a noticeable bulge or oozing Does it buzz with no input?
  13. alfa88

    figuring out an amp circuit.

    I hope you're going to be connecting this amp to a power supply (DC) and not simply to a transformer (AC). Otherwise all bets are off. I get a bad feeling when you have to ask how not to get electrocuted. #1 make sure everything you're going to wire is unplugged and do a double check before...
  14. alfa88

    figuring out an amp circuit.

    You found the holy grail for your amp. E1 is Signal Ground for Left(1) input, E2 is Signal Ground for Right(2) input, E3 is Output Left(1) Ground and E4 is Output Right(2) Ground. I don't see why you can't tie all of them together with the Power ground. The Fuses are protection for your...
  15. alfa88

    figuring out an amp circuit.

    I'd leave the TPs/variable resistors alone. Have you tried to look for a receiver schematic? The connections I'd expect are 2-input, 2 output, +V, GND, -V. But ignoring the E1 - E4 wires is troubling..
  16. alfa88

    figuring out an amp circuit.

    Totally Guessing B+ would be the power supply Plus which could be anywhere from 9 to 40 Volts. Hopefully there are pads on the mounting holes you could use to find the ground wire. I would think there would be a connection for a Negative power supply, -9 to -40. TPs are indeed test points to...
  17. alfa88

    Inverter ... Mr. Gary Lecomte

    Better post a pic, schematic or preferably both if you want an answer.
  18. alfa88

    For Sale: Karma thread.

    Will they fit in a small flat rate prio box? (10"w X 2" h X 6" d ) Otherwise I'd have to step up my game to a medium flat rate box.
  19. alfa88

    For Sale: Karma thread.

    I've recently caughtt the vacuum tube bug so I'm looking for ~ 100uF @ ~ 300Volts or more:D
  20. alfa88

    For Sale: Karma thread.

    Caps? Am I too late or do you still have the capacitors?
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