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Wiring a led in pararrel to preamp on/off

Discussion in 'Pickups & Electronics [BG]' started by Legan, Dec 3, 2013.

  1. Legan


    Apr 17, 2009
    Hello. I've acquired an Artec SE3 preamp http://artecsound.com/pickups/electronics/se3.html
    and I'd like to wire a led to the preamp/jack that lights up when plugged in.
    There was a similar thread here http://www.talkbass.com/forum/f38/adding-led-pre-amp-circuit-411935/

    It works no doubt for the part of plugging in/lighting the led but what I don't quite get is that if I went for a similar setup how do I wire the battery and the switch from the jack onto the preamp as shown in the artec diagram?
    (The battery + just goes on the ring of the jack in the talkbass diagram)

    I'm quite hopeless when it comes to electronics so any help you might be able to offer would be of great assistance :)
  2. Dave Curran

    Dave Curran Lilduke

    Jul 27, 2013

    You have the two battery connections on the left of the main board on bottom. Then 3 terminals that go to the output jack. The first (or middle of 5) Labeled SW" is the switching terminal that goes to output jack ground and turns on the pre-amp. Go from that to ground.
  3. Legan


    Apr 17, 2009
    So based on the talkbass diagram i'll just "continue" wiring the battery + from the ring to the preamp +terminal? This is where it gets weird for me, as the battery IS wired to the ring, which is supposed to go to "SW" according to artecs diagram and normal ground to "gnd"
    I'm certainly still missing something here.

    Can I just add a small wire between the "sw" and "b+" terminals in this case?
  4. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    You are going to find that having an LED on your bass as a power light will greatly shorten battery life. An LED bright enough to be seen may draw as much if not more current than the preamp. That's why you don't see them on instruments.

  5. Steve Dallman

    Steve Dallman Supporting Member

    LED's are fairly high current, with an average 20mA current draw. Consider your preamp is probably in the 1mA current draw range, you will shorten battery life. Most effects pedals draw less than an LED. There are low current LED's but they are not very bright.
  6. Legan


    Apr 17, 2009
    Mine are 2mA and I deemed it bright enough for this purpose. While it will shorten the life of the battery, I doubt I'll burn many of them since this bass is my first build and will most likely not be a pleasure to play ;)
  7. Dave Curran

    Dave Curran Lilduke

    Jul 27, 2013

    NO! Then you are shorting the batter + to the -. The talkbass diagram didn't include a separate switch in the jack to turn on the pre. Your pre uses a third terminal (the ring) going to ground (the sleeve). The other one uses the battery in-line with the jack as a switch. (tip to sleeve) Both ways take you back to ground @ battery from the pre, through the jack.

    Just hook the LEDs to the ring terminal on the jack. It's the middle contact point.
  8. Legan


    Apr 17, 2009
    So would it be as simple as to just follow this diagram and wire a resistor to the battery+, led to resistor and the other end of the led to the ring terminal?

  9. The LED goes from the positive terminal of the battery to the current limiting resistor, and the current limiting resistor goes to ground. Simple as that.

    +1 to greatly decreasing battery life.
  10. Legan


    Apr 17, 2009
    Thanks for all the replies. Really simple solution at the end ;)
  11. BassGyver


    Jun 29, 2004
    Use a very bright led, so you can use it a very low current and still get enough light.
    I run a blue led as low as 0,2mA (200µA) and get enough light to use it as a power indicator. I can't look at the led directly if i run it at 20mA...
  12. Another option is to use a stereo jack on the bass, connect the positive power feed to the preamp to the "ring" contact (negative to ground of course), and power the preamp with an external battery or AC supply. You will need a stereo cord between your bass and the power supply so make sure you have two or three of them at all times because you won't be able to depend on others to lend you one when your normal cord breaks.

    I've operated all my basses this way for three years now and haven't touched a 9v battery since (other than for smoke detectors). I added LEDs to two of them so I would know if power was present at the preamp the same way discussed here.
  13. Dave Curran

    Dave Curran Lilduke

    Jul 27, 2013
    His pre requires a t/s (mono) cord. When it's inserted it closes the r/s contact on the t/r/s jack and completes the ground to the pre amp.

    Legan, if you want to use the existing battery, hook up from, batt + --> resistor --> led --> ring terminal on jack. You could also use a seperate battery going the same way, but you'd have to hook up the new 9v - , to the sleeve terminal of the jack. You would still wire it the same way as using the exsiting battery. Remember LED's are Diodes, they will only light up when powered +,+;-,-
  14. ????

    I don't think you actually understood my post. I power the internal preamp in my bass externally by shorting the existing battery connector and bringing the power in through the extra lead available in a stereo cable.

    Having the ability to power the internals externally - I use a wallwart - means I can load the bass up with as many LEDs as I want. It also means I don't use 9V batts any more.
  15. Keith Medlock

    Keith Medlock

    Aug 12, 2013
    I use a 20ma LED as an indicator since I rewired my Carvin. Anyone who thinks LEDs are high current draw is mistaken. I run mine with an 18kohm resister pulling less than 1ma and its still plenty bright to use as an indicator. Try that with incandescent, et al. If you really want to get serious and scrounge power get rid of any polarity protection diodes in series and replace with a parallel diode plus fuse. I'm just finishing my Carvin rewire, but this site won't let me load photos into posts. Weird for a forum.
  16. bassbenj


    Aug 11, 2009
    I use the external power thing as well. I have One Spot supplies installed inside of my amps. A switch on the front shorts the ring wire so you can still use a battery active bass as well (other wise it puts 18 volts on the bass).

    And I've used the blue LEDs as well they are EXCELLENT. I just got one at Radio Shack listed as "ultra bright". And it is. So it can run on VERY little current and still be quite visible. Also I use some ultra bright greens ones which are also excellent. The red or yellow ones, not so much.

    Interestingly, I just measured the current on led fretless marker strip on one of my basses. Even though it has LEDs up and down the neck, it still only pulls 2 ma which is not so bad. I'm thinking of switching from the headstock battery to the internal 9 v battery to power it. Which of course on the external power basses would be powered by the head.

    Still I'm a bit paranoid and if I had power LEDs on a bass I'd run them from a separate battery. As it is if I switch any active bass back to battery power it's wired so the power LED does not come on to save the battery life. Though now I'm thinking that probably wasn't necessary.

    I especially love the new lithium non-rechargeable 9v batteries. Tons of power for lasting and also last years if off. But expensive.
  17. 1958Bassman


    Oct 20, 2007
    The first post clearly shows a stereo jack on the diagram. Also, the cable doesn't need to be stereo since the battery is in the instrument. This allows using ANY cable with good integrity if the usual one is damaged. If the bass has the option to be used in active OR passive mode, a dead battery won't stop a gig the way a bad stereo cable will. In addition, if the power supply conductor in the cable loses wire strands because of flexing and bending, it will eventually make noise when the strands make/break contact. If the LED is wired to limit current, the battery should last for weeks in the event that the cord is plugged in.
  18. Not sure why the issue of stereo keeps coming up - of course it has a stereo jack. I'm also not sure the point in your post but we've been through all these arguments in past threads on the topic. Feel free to talk yourself out of it for whatever reason you deem worthy - it's worked great for me over the last three years. I'm betting you haven't tried it so you're arguing from theory not experience. Not having to worry about batteries is another benefit.

    I will acknowledge that the reasons to use external power are somewhat thin if you only think about it from the standpoint of 'what can it do for me' and 'what are my risks' but I like minimizing the amount of poisonous chemicals I contribute to landfills and I haven't had any of the issues you've cited when I play but keep in mind that I play in church every Sunday so I'm dealing with a pretty benign environment to use this stuff.

    Others who have done this can post their experiences if there are any hard rocking giggers out there. I think the other poster who contributed to this thread rewired his amps to do this but I don't know if he's in a band. I rewired my pedalboard the same way but I don't use that in church.
  19. +1
    This is what I did also