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  1. colum

    Pulse Width Modulation

    I have a small DC motor that is driven by 2 555 timer circuits and 2 Pots and a Transistors in PWM mode...I know the first 555 is the timer and the second 555 does what...does it amplify each pulse at its peak or does it make the pulse longer duration. I would greatly appreciate it if...
  2. colum

    LED light receiver

    I have a robotic arm that aims a Red LED at a dart board and works very well. I need a Diode that receives this light . is there a circuit or Diode that I can use to activate a visible LED to indicate a bullseye Thank you for reading this .....Jeff Thanks Steve for teaching me how to hook up a...
  3. colum

    LED string

    I have a mechanical arm that has 4 limit switches that is hooked up to 4 LEDs. 3 of the LEDs light up fine when activated but the last LED of the chain seems to take all of the power of the 9v battery when activated I have switched LEDs etc but always the last Led prevents the first 3 from lighting
  4. colum

    Green laser

    Thank you for reading this I want to get a Green Laser with an IR filter also if possible to get a focusable unit all built in I am reactivating a Lab heavy duty chain driven pointing device and have all the motors wired up and intend to use it as a type of light emitting device to a dartboard...
  5. colum

    Bicycle generator

    I hurt my knee and need to exercise on my stationary bicycle so I want to attach a DC motor to the wheel to charge a battery I want to add an analog Volt meter and an analog Ampere meter to observe output. but when I quit cycling the battery turns the bicycle in the opposite direction . I would...
  6. colum

    LED IR

    I have many older diagrams on how to hook up an IR Detector and they show from no input Resistor to a Million ohms. I want to hook up an Emitter Led and I figure that input Resistor should be 150 ohms at 9 Volts to an IR Detector that is also 9 volts but what determines the Resistor ( if any )...
  7. colum

    Variable Hertz

    I'm trying to clear up old projects and I need help with this last one. I want to generate an AC signal at variable 350 t0 450 HZ at 115 Volts and about 10 Watts max. a square or Sine or Triangle wave would do and it would be nice if it was based on a 555 since they are easily available and it...
  8. colum

    Wire wrap circuit

    I've been away for a long time from circuit building and at that time there was two methods that I used one was Getting copper clad boards and chemicals to remove unwanted copper and leaving a copper circuit. The easier one was the Wire wrap and I used it alot. It had elongated legs on IC...
  9. colum

    741 OpAmp

    I find it odd that I posted a circuit requesting a pin out of a 741 Op Amp and not only did I not get a pin out but I got dragged into a long discussion about what I was going to do with this circuit and after threats to terminate the discussion apparently it was terminated.. I think this is...
  10. colum

    Op Amp 741

    I am trying to find the wiring for a 741 Op Amp as a simple Buffer of a Sine Wave with a 15 + Volt and a 15 - Volt Regulated supply.. I hope my diagram shows up and if it doesn't I would appreciate advice on the pin numbering...Thanks...colum
  11. colum

    Power supply + and -

    I want to make a Power supply using A 7812 + Volt and a 7912 - Volt for a dual supply but several of my books show different wiring for the 7912 -V so if someone would just tell me the simple wiring for the Transformer Center Tap (ground) and the -V in and the -V out , there are 3 legs left to...
  12. colum

    Wanted: Free

    I have quite a few OLD Crystal timing generators that anyone can have if you tell me the Hertrz And also older ICs some are new some were pulled from early Apples etc I also have old electric gauges of different types that are quite heavy and you would pay postage only. If you were making an...
  13. colum

    Electric interference

    I bought a new car and want to install a wireless camera in the front licence plate so the signal would need to cross the engine so my question is---Would the auto Electric interfere with the wireless signal or would this need to be hard wired. I wonder if the generating of DC causes electric...
  14. colum

    For Sale: Antique gauges

    I have a collection of 2 kinds of Tuned Reed Vibration gauges one type measures frequency of AC supplied and ranges from 20 hz to 400hz and Lo volt to !25. All reeds vibrate but I cannot test the 400 hz The other Tuned Reed types are non electric and sense the RPM by making contact with the...
  15. colum

    IR Leds or Visible ?

    I want to run about 75 ft of Fiber Optic cable as an ON Off type of switch.. All of the LEDs that I have are IR, so my question is...Is IR better for long transmission and receiving or is visual Leds better since the activating light can be adjusted in intensity. Would it be better to use an...
  16. 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]
  17. 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...
  18. 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
  19. 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...
  20. 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...
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