Search results

Search Forums New Posts
  1. K

    First ever project, How do I make randomness???

    Are these incandescent lamps or LED's? The 555 can output up to 200mA. The output of the 555 can pull a load high or low to turn it on. Just depends on what the lamp is connected to. In this case you connect your lamps in series. One lamp in connected to the +supply and the other is connected...
  2. K

    Product PCB Button Pad has a short circuit

    First...Why all the vias? Are they needed? I would use a Dremel with a very small (1/32"?) burr to cut a line through the shorts to separate them. Or just an Xacto knife to scrape a line. Ken
  3. K

    Easy Fix

    http://www.lowcostcontrols.com/2-pole-contactors/30aontactor--2-pole-definite-purposeontactor-p-405.html http://www.31eng.co.kr/e_html/pro04.php Sorry, got to run. Ken
  4. K

    First ever project, How do I make randomness???

    True randomness is difficult. It might be possible to drive each pair of lamps with with a LM555 astable oscillator. Each 555 would be operating at a different frequency. With the switch off, all three pairs would be continuously alternating between the two lamps, fast enough so that the eye's...
  5. K

    Anybody know where I can get a collection of electrical symbols clip art

    Bob, I disagree. I think the schematics are beautiful! Well, for the price. Ken
  6. K

    Anybody know where I can get a collection of electrical symbols clip art

    ExperssPCB is a free schematic/PCB program. The schematic program is pretty intuitive and easy the make new symbols or modify existing ones. You can export the schematics to Bitmap or Metafile formats. Note, it's not a simulator. http://www.expresspcb.com/ Ken
  7. K

    Narrowboat (Waste) Holding Tanks - LED level indicator

    Revision of my earler circuit. +Supply >N.C. switche> resistor> LED>ground. One arrangement for Red and one for Yellow. When the switch closes the LED lights. Ken
  8. K

    How to safely wire or utilize a switch

    Y2KEDIE, A GFCI only works if there is an alternate path to ground from the hot line. Taking apart a line operated lamp would just expose the "kid" to line-to-neutral electrocution Healthyou, How about a photo of what you are trying to do. Ken.
  9. K

    Narrowboat (Waste) Holding Tanks - LED level indicator

    Maybe a little more simple. +Supply > resistor> LED>ground. N.C. switches across the LEDs. One arrangement for Red and one for Yellow. When the switch opens the LED lights. Ken
  10. K

    What is your favourite type of component?

    Wire! ;) Ken
  11. K

    4 stilo holder

    If you are asking about the arrangement of the copper strips to make a 4-battery pack, then this is what you want. ( I hate PAINT!) Ken
  12. K

    How to switch off an audio signal

    Can you post a schematic of what you have? I see a small issue of knowing when the input speech has ended and when the output speech starts. Is there a clear distinction that your circuit can recognize? Then it's a pretty simple (he bites his tongue!) to sense the output and use the analog...
  13. K

    Variable power supply for under 3 volts

    With a little Googling: https://i0.wp.com/www.electronics-lab.com/blog/wp-content/uploads/2008/10/lm317.gif You can use a transformer with a center tapped secondary, a bridge rectifier and two filter capacitors to generate the positive and negative DC sources. Ken
  14. K

    Variable power supply for under 3 volts

    I would add a second, small -1.25v reference supply. Connect the commons of both the positive and negative supplies together, Then connect the bottom of the resistor/pot LM317 programming string to the -1.25v supply. That allows you to control the output down to 0v. Ken
  15. K

    electronic cycle counter

    Instead of a cycle counter, how about a run-timer timer: http://www.amazon.com/DC12-36V-Meter-Hourmeter-Tracking-Engine/dp/B00EYZCSYS/ref=sr_1_2?ie=UTF8&qid=1420069620&sr=8-2&keywords=hour+meter+12v Ken
  16. K

    electronic cycle counter

    Bob, I'm assuming that you have little or no electronics construction skills, and are looking for a mostly off-the-shelf solution. Ken
  17. K

    Conductors in Exhaust Plenum

    Not sure what RGS is, but this sounds like it involves a commercial enterprise. I would suggest you hire a licensed electrician...or a good lawyer. ;) Ken
  18. K

    Transistor base resistor calculation on 2N4401

    A rule of thumb that I use to assure CE saturation for switching transistors is to use base current of 1/10th the expected collector current. So for a collector current of 150mA, I would select a resistor for 15mA base current. As in post #2: Rb=10(Vin-0.6)/Ic Ken
  19. K

    Transistor base resistor calculation on 2N4401

    Also need to state what you what to use this 2N4401 for. Do you want to operate in a linear mode as in an audio amplifier, or in a switching mode to just change between open and saturation. Ken
  20. K

    Help with finding a resistor to drop 220v to 110v

    Some times you just spend a one-off price for a prototype part at a down the street Radio Shack, before you buy in bulk for production. Especially if you have little or no experience. ;) Ken
Top