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  1. J

    LTSPICE and 3 phase w/ transient analysis - SLOW!!!!!!!!!!!!!!

    I been messing around with LTSPICE lately in an attempt to play around with some 3 phase wiring ideas I had been trying to understand. All was working out well till I tried to simulate a step down isolation transformer according to this pdf file here page 44...
  2. J

    3 phase drum switch wiring -- validation

    The attached photo is the only paperwork I got for the drum switch. There is no form350-21c to be found on the internet and since A&B was sold, Rockwell automation doesn't know squat. But, I have a 3 phase motor. I plan on hooking this up for maintained contact with the following wiring...
  3. J

    recommend a multimeter

    Just as the title says. I had a decent sears multimeter from 20 years ago and it worked great for years. But good things never last a lifetime it seems. Calibration seems to went wonky with it and I am getting all kinds of wacky readings. Clearly it is more price effective to buy a new meter...
  4. J

    another motor question

    I managed to grab an industrial 1.5 HP baldor DC motor for the right price out of luck today. I am trying to understand one important thing. How voltage and current relate to the motor. From what research I have done to my limited understanding. Voltage controls the speed of the motor. The...
  5. J

    Universal motor bi-direction speed control

    I found a universal motor. I know these can be used on either AC or DC and to reverse the direction all one needs to do is reverse the polarity of the field coils compared to the communicator? Now what about speed control, I have read that you can use a triac to act as a speed control for a...
  6. J

    solution to soft start an ac induction motor

    Just as the title of the thread ask, I am wondering what type of solutions I have for soft starting a 120v ac induction motor with starter coil and capacitor start? It is a 1HP. This is on a lathe so I would like to stick to 120V to avoid any extra external electronic motor controllers needed to...
  7. J

    where did it go?

    Didn't we at one time have a sticky thread about timers? Hence the note on the LED sticky, "another" work in progress? Or have I totally lost it?
  8. J

    Class A amp questions

    I bought this tip31 transistor and it says on the package good for audio. I figured why not mess around with it in simulation to see what it is capable of doing. Here is my results. I followed this guide for the design. http://www.electronics-tutorials.ws/amplifier/amp_2.html Here is what I...
  9. J

    JVC receiver RX-715VTN

    I acquired a JVC receiver RX-715VTN broken of course. I would like to see if I can fix it. The problem is that the output is very muffled in the speakers (low volume) and there is white noise on the output now. You can hear it in the speakers. I searched and found plenty of people willing to...
  10. J

    where did resqueline go?

    The title says it all. been a while since he posted.
  11. J

    Removed anode from my SCR

    Why would they cut off the anode pin on a SCR? Would make sense if the tab was electrically connected to the anode, but I looked at the datasheet and I didn't see where it stated this. http://cs.utsource.net/goods_files/pdf/22/22042_STMICROELECTRONICS_BTW69N1200.pdf edit: well the MM reassures...
  12. J

    Boost converter

    Is it impossible to think that I could use a 12V 50A max car battery charger transformer and make a 45V boost converter to run some steppers with a current draw of 2A per motor. total of 6A. I want something simple and I already have this transformer, so even though it is not that efficient of...
  13. J

    PCB footprint question?

    Can anyone look at my footprint that created for the LMD18245. I just need a set of experienced eyes that can maybe point me to anything I might have done wrong. Datasheet: http://www.ti.com/lit/ds/symlink/lmd18245.pdf Pin 1 - Pin 15 = .700mils center to center on adjacent holes in same...
  14. J

    Amplifier circuit questions

    1. The gain of the op-amp is 10? 47k/4.7k = 10 2. This is a non-inverting amp? 3. The transistors in this setup kind of confuse me. The PNP transistor connected to the +15V side will only turn on when the base is more negative then the emitter. The 180Ohm resistor will have a voltage drop...
  15. J

    Safest way to switch 240VAC

    I have a generator I bought for my home. I want to be able to hook it up to the breaker box so that when the power goes out I just head out and turn on the generator. My first thought was to use a relay to connect the generator to the breaker box when the power went out. But, this got me to...
  16. J

    Wanted: PIC programmer.

    I am looking for a PIC programmer like the pickit2/3. Something that is compatible with MPLAB is preferable. Maybe someone bought one and now has no use for it. I will be willing to take it off your hands for a reasonable price. Or at the very least, does anyone know where I can get one for...
  17. J

    How do I use this megger tester?

    So I found this contraption in my grandfathers old belongings. It has some stuff on there about insulation resistance. If I understand this correctly, it is used to test like the windings in a motor or maybe even a transformer? The thing is old, so it even has a crank on it to produce the high...
  18. J

    Antenna help

    Davenn, I think this is probably a good one for you to answer, but I will take anyone's advice. :D I have one of these Network Extenders, femtocell, devices from verizon. Recently my neighbor informed me that he was gonna cancel his landline and internet to get a pre-paid cell since he gets...
  19. J

    Help in deciphering how this DAC thing works.

    I know I am asking a lot, I understand some C but this is pushing my limits. Is there anyone out there that can help me understand this a little more. I have done my homework, for micro-stepping you need to control the current in the motor windings in a certain order. The LMD18245 is a chopper...
  20. J

    Questions regarding capacitors

    I am posting this here on request. I started a pm to ask this question since I did not want to highjack another thread at the time, but the information is to good to keep it private so we will just continue this discussion here...
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