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  1. colum

    For Sale: FREE motors (synchronous/stepper)

    I have a bunch of 115v Synchronous from 3 to 15 watt / small steppers / motors that I have gathered over the years. The Synchrons are either brass, bronze, steel or alum. It cost 5$ for postage from NY to Ohio for one...colum [Edit by moderator: changed title to clarify]
  2. colum

    Photodiode or Phototransistor

    Thanks Dave your response is appreciated. The old books I have represent Photodiodes as having a C to B and E as the light sensitive element, I'm going to toss these old books they are misleading....colum
  3. colum

    Photodiode or Phototransistor

    I bought a 3mm Ambient light sensor at Radio Shack the lens is clear and a long and short leg there is no circuit description and some of the folks say its a Phototransistor. From some description of the difference is that Photodiode has a Collector to Base circuit and the Emitter is the Light...
  4. colum

    Hello from Midhudson NY

    I'm fairly new at this forum and I can not access my messages theres a lock on it so how can I get instructions on how to use the tools ...colum
  5. colum

    30v DC to 27v DC

    Hi Kris I'm new at this and my response (quote) ended up in an unexpected place anyway thanks for your valuable advice...colum
  6. colum

    30v DC to 27v DC

    Thanks Kris for your advice I will contact Digikey as you suggested and I must find a circuit to use Zeners as I thought the would be in paralell .. Be well and thanks ..colum
  7. colum

    30v DC to 27v DC

    In order to drive an AC generator at the correct speed that uses a 27v DC motor for rotation...The 27v DC motor draws 6amps. I have built a power supply that delivers 30v DC so I must lower this voltage 3v. I would appreciate any help on how I would do this without starting all over again...
  8. colum

    DC motor control

    PWM Thanks Steve but getting parts for a PWM or any other driver for a 6 amp motor is getting complicated however I did manage to do it with transformers except for the voltage jump and I can not figure out how to solve that. I did variac the AC volts going to the 24v transformer to show...
  9. colum

    DC motor control

    Please bear with me with another basic question I want to supply 24 to 27v DC to a DC motor (not PM) speed is important as it drives a generator 123v AC line to 24v CT transformer 28V from transformer 28v to full wave rectifier 27v out from rectifier 27v to DC motor but suddenly...
  10. colum

    Bleeder resister size

    Hi Bob. Since this is just for bleeding a capacitor thats disconnected from the power supply would it make a difference and would a permanently installed bleeder require different ratings..Thanks...colum
  11. colum

    Bleeder resister size

    Thanks Dave
  12. colum

    Bleeder resister size

    I want to put a resister accross a DC supply leads to discharge the voltage in the capacitors. This will be only used to discharge after each useage. I expect the voltage to be from 1 to 125v DC and the amperage to max of 3 amps. I checked all of my books and the internet and I could not find...
  13. colum

    DC Motor drive

    Thanks for your advice Fish. I had forgotten about PWM drives and I can use 411 type transistors which I have used in PWM drives before but for much smaller mtrs anyway its a hobby and I have parts to burn up...Thanks...colum
  14. colum

    DC Motor drive

    Im new at this so I hope I don't make the attachments too large or small. I built this circuit and it seems to work for a small DC motor but I need to drive a motor that takes 1 to 6 amps at 27v DC problems--DC volts shoots up to 40v from27v when Mtr turned on Pontentiometer---Overheats...
  15. colum

    Missing Thread

    I started a new thread yesterday and I can't find it. I'm new at this so how long does it take to hit up...Thanks...colum
  16. colum

    Looking for vintage parts and selling some

    I wonder if there is a forum that you can exchange or buy used parts to repair or rebuild very old electromechanical and old test equipment. This is a hobby of mine and I have lots of unfinished projects but parts (such as Variacs etc etc) are hard to find. I have panel meters and motors for...
  17. colum

    Adding Transformers

    Thanks (*steve*) will do I like safer..colum
  18. colum

    Adding Transformers

    A single transformer is overheating so can I add another transformer with the same volt output so that would make it two with their out put joined.. The purpose is to drive a 6 amp motor at 27 volt DC from 115 volt AC or would it be better to join the DC after the rectification and then smooth...
  19. colum

    27vDC 6a from 115vAC

    Thanks again Harald. Its the frequecy that s most important.. colum
  20. colum

    27vDC 6a from 115vAC

    Hi Steve. I'm trying to create a stable frequency from a DC motor rotating an AC generator and I know when the AC generated has a load it will change the speed of the DC motor and I think you are right it will only work if theres a feedback from the generated voltage and if this feedback is from...
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