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  1. dorke

    How to convert hight voltage ac into dc?

    Since you asked: With your level of knowledge, that "something else" is: Don't try it ,most probably you will hurt yourself or others !!!
  2. dorke

    serial interfacing

    "it seems that the hardware circuit that i have on bread board is not feeding anything to pc" How did you check this? Have you used a scope? The circuit is taken from Maxim App note 827 ,it should work. Consult the datasheet for sequence of operation and timing the device
  3. dorke

    Battery Level Indicator

    Here is another simple way to do it( i think you can't beat that simplicity).:cool: Using only a Zener diode as a comparator.Like the 1N47xx series It isn't very accurate , but should be good enough. If more accuracy is needed/wanted ,you can use the TL431 instead of the zener. calculate the...
  4. dorke

    Car battery jumpstart gadgets

    We do have to count the Ozon layer shrinkage into account. That is(was?) a big issue in Kiwi-land.
  5. dorke

    Car battery jumpstart gadgets

    We are, but it's interesting ;)
  6. dorke

    Casio PT80 Keyboard - suspected transistor failure

    One more thing, Can you please post a clear photo of the Tr from the legs side.
  7. dorke

    Casio PT80 Keyboard - suspected transistor failure

    About that transistor, The board gives the details(photo): It is a 2SC2603-F ,Looks like the board has a few of them. It could be the cause of the problem, but the fact that you puled it out and there is no noise could merely be because it is in the "sound path" , i.e. taking it out would...
  8. dorke

    Casio PT80 Keyboard - suspected transistor failure

    Hi Chas, Poking around and shorting devices is a practice that should not be done ,it can be destructive and even dangerous ! The only time you can try that is if you have a schematic of the equipment and deduce(for sure!) that a short at a specific point can be safe. While trying to repair...
  9. dorke

    Taylor Electric valave voltmeter model 172A-schematics/service manual

    My tester has a mechanical meter issue: I can zero it mechanically while it is horizontal position. If I put it in it's vertical position the needle hits the lower side as if gravity drags it down. In horizontal position,it also zeros electrically and measures correctly in ± DCV.
  10. dorke

    Taylor Electric valave voltmeter model 172A-schematics/service manual

    It is a 3 valve model,radiomesum site is wrong to say it is a 2 valve one. The 2nd diagram you have posted agrees with 3: 1X,2X ...
  11. dorke

    Car battery jumpstart gadgets

    The simplest way to jump start a car ,long forgotten by now: The hand crank see here. Car manufactures can provide it easily if they wanted to ,but they obviously don't. It is practically fail safe. On the issue of electric cars: 1.It is obviously in the near future for reasonable prices...
  12. dorke

    Taylor Electric valave voltmeter model 172A-schematics/service manual

    Nasa we have ignition ! Found one wire open on the front panel on/off switch(switches both phase and neutral). Now the valves warm-up and there is the ability to zero. I measured volts(tried only DC for now) reading is not accurate,needs more work. A question: The line cord has 3 colors...
  13. dorke

    Taylor Electric valave voltmeter model 172A-schematics/service manual

    At first glance it looks similar. In my meter,there are 3 valves : one ECC82 and two 6AL5. they don't heat-up ,looks like there is a problem with the transformer(no voltages on the secondary. Transformer info? In general,it looks like there are much more parts(caps?) in the meter. The "COM"...
  14. dorke

    Taylor Electric valave voltmeter model 172A-schematics/service manual

    I bought this 1961 VTVM for 5$ at a flee market. It needs repair and reconstruction. Couldn't find any docs on the WEB just a few pictures,like this one. If you have any please post or link to. Thanks
  15. dorke

    Comparator - Battery Cutoff

    It isn't new,the datasheet is from 2006. The design you have is faulty. You can't expect to have 3.1V on the zener when you feed it 3.1V through a 10k resistor. lets' say you feed it with 3.15 V,the current would be (3.15-3.1)/10k=5μA,that is way too low. You should use a lower voltage zener...
  16. dorke

    Help Identify Component on Dynex TV Power Supply BA71G0F01043

    The proper way is to look at the service manual. But it may be easier to get help from Dynex support here
  17. dorke

    Help Identify Component on Dynex TV Power Supply BA71G0F01043

    Welcome to EP. It is a HV transformer. Was it shorted? why do you want to replace it?
  18. dorke

    Comparator - Battery Cutoff

    I agree with the above notes. More than that, I would say there is no need to reinvent the wheel...;) Here is 3 pin under-voltage detector that will do what you need in every way better: smaller,cheaper,more accurate,less power and way simpler. There are many others, Enjoy
  19. dorke

    NOT GATE Analog Circuit

    Welcome to EP. Logic operations are by nature digital. Using a transistor ,which is an analog device by nature to create a NOT(invert) gate is already an analog implementation.
  20. dorke

    Car battery jumpstart gadgets

    The "new era" is upon us.;) The newest thing is the use of super-caps in car jump starters. These caps are in the range of the hundreds of Farads and can store enough energy to start a car. These miniature jump starters are small and lightweight about, 1kg ! They aren't very cheap 70-200$...
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