5

I tried the following circuit but the LEDs for me are always on and don't blink, i checked connectivity, changed capacitors and tested transistors but same problem. what could be the issue? enter image description here

edit: left transistor is 13001 s8d, right on is 13002 HJ B1

picture of the setup:

zakaria kais
  • 55
  • 4
  • 2
    Show a photo of your setup and add in a part number and link to datasheet for your transistors. – Transistor Jun 25 '20 at 14:52
  • 3
    Compare TO-92A, TO-92B and TO-92C transistor packages - it is easy to mix up base emitter and collector. – RedGrittyBrick Jun 25 '20 at 15:01
  • 5
    Wow, a legitimate breadboard! Haven't seen one of those in YEARS! – DerStrom8 Jun 25 '20 at 15:08
  • 2
    Those don't look like 47k resistors to me – DerStrom8 Jun 25 '20 at 15:10
  • yeah they'r 10k, is it that important? – zakaria kais Jun 25 '20 at 15:13
  • 6
    Those green "resistors" could be "inductors" instead. – Mike Schroedel Jun 25 '20 at 15:13
  • 2
    The resistance will change the frequency of the flashing, though 10k instead of 47k would probably be fine in this case. As Mike said though, green devices in these packages can be inductors, so you might have a pair of 10mH inductors instead. Measure their resistance (out of circuit) with a multimeter and confirm whether or not they are indeed 10k. – DerStrom8 Jun 25 '20 at 15:17
  • 1
    "*yeah they'r 10k, is it that important?*" That's why I asked for a photo. What else are you not telling us? Where's the link to the transistor datasheet? – Transistor Jun 25 '20 at 15:21
  • 1
    It does look like the pinouts of the transistors are correct, though I don't know what the effect of using two mismatched transistors would be in this design – DerStrom8 Jun 25 '20 at 15:21
  • 1
    @Transistor I believe these are the datasheets: https://alltransistors.com/pdfdatasheet_cdil/cd13001.pdf and https://pdf1.alldatasheet.com/datasheet-pdf/view/888528/SEMTECH_ELEC/13002.html – DerStrom8 Jun 25 '20 at 15:22
  • 2
    +1 just because it's an awesome build up :) Stupid question, always on means for your eyes or did you measure? – po.pe Jun 25 '20 at 15:28
  • thanks :) for the measurements my multimeter is broken so i'm relying on my eyes atm till i get a new one. – zakaria kais Jun 25 '20 at 15:38
  • 1
    Well you can't really determine whether the device is a resistor or an inductor just by looking at it. – DerStrom8 Jun 25 '20 at 15:49
  • 5
    turned out you are right those actually aren't resistors, i changed them for different ones and now the circuit works :) thanks for the help. – zakaria kais Jun 25 '20 at 16:04
  • 1
    Good news! Thanks for the update! – DerStrom8 Jun 25 '20 at 16:08
  • 1
    Surprised some parts did not heat up or worse – Tony Stewart EE75 Jun 25 '20 at 17:01

1 Answers1

2

Oh this is a simple one. Those sea-foam green "resistors" are actually inductors. The green color is used to indicate it is an axial lead inductor specifically so they wont be confused with resistors.

This question actually addresses this:

How to visually tell the difference between axial inductors and common resistors?

Jeffrey Phillips Freeman
  • 1,233
  • 8
  • 24