Connect with us

Calculating values...

Discussion in 'General Electronics Discussion' started by Gav2k, Apr 17, 2014.

Scroll to continue with content
  1. Gav2k

    Gav2k

    3
    0
    Apr 17, 2014
    Hi,

    Quick summery..

    Basically a friend has a bmw x5 which has an issue with the stereo, bmw back in 2002 made a part to fix the issue but this part has since been discontinued and the replacement part only fits newer models.

    The part looks to be a simple resistor and capacitor but obviously I need to values which bmw won't give out to be able to order the parts and solder them in.

    The picture (hopefully attached to this post) shows the circuit and it's a car so let's assume 12-14.4v dc.

    It has to come out as 12-14.4v but the bmw specialists do tell me the circuit is purely designed to cause a 5 or so second delay on powering up the systems amplifier.

    Can any of you guys work out what values I need so I can pop into maplins.co.uk and pick the parts up.

    Thank you in advance
     

    Attached Files:

  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    Hello and welcome to Electronics Point :)

    That diagram doesn't have component values for the resistor and the capacitor. There is one clue: the capacitor has a positive symbol on one side, which means it's probably at least 1 µF.

    You could try a 470 µF capacitor and a 10k resistor. This combination has a "time constant" of 5 seconds, but this doesn't mean it will necessarily cause a delay of 5 seconds; that depends on the characteristics of the things on both sides of the circuit. It's likely the delay will be shorter than 5 seconds. In that case, you can try a higher resistor value. So you could buy some other values at the same time - 33k and 100k, for example.

    Here are references to parts on the Maplin site:

    Capacitor, electrolytic, 470 µF, 16V: http://www.maplin.co.uk/p/470f-16v-85c-radial-electrolytic-capacitor-vh46a
    Resistor, 10k: http://www.maplin.co.uk/p/metal-film-06w-10k-ohm-resistor-m10k
    Resistor, 33k: http://www.maplin.co.uk/p/metal-film-06w-33k-ohm-resistor-m33k
    Resistor, 100k: http://www.maplin.co.uk/p/metal-film-06w-100k-ohm-resistor-m100k

    Good luck :)

    If you need any more info, just ask.
     
  3. Gav2k

    Gav2k

    3
    0
    Apr 17, 2014
    After looking into it more it's a 3-5 second delay so it seems to be correct. Are the parts directional?

    Thanks so far

    Gav
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    The capacitor is polarised. The polarity is marked on the side of the component. Also, the positive lead is longer than the negative lead. The resistor isn't polarised.
     
  5. Gav2k

    Gav2k

    3
    0
    Apr 17, 2014
    That's great. Thanks for the help!!
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-