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Thread: Illuminated AV Switch and Plecter Lab Soundboard Clarification - Wiring Options

  1. #1

    Question Illuminated AV Switch and Plecter Lab Soundboard Clarification - Wiring Options

    I assume that like most things in life, there is more then one way to accomplish something.

    If you would like to wire an Illuminated AV Switch to turn on when power is supplied (assuming "kill key removed"), I THINK I see a few ways of PROPERLY accomplishing that.
    I would like for guidance/confirmation on those methods.

    1) Wiring the AV Switch LED (I believe most TCSS illuminated switches are like this one: http://www.thecustomsabershop.com/16...itch-P903.aspx) to the battery leads (Skipping the Sound Board):
    Either:
    a) Calculate the resistor needed using (Vs-Vf)/If. The Switch is Vf=3.0V, If=20ma.
    For the PC & CF boards, the suggested Battery is Vs=7.4V, and this calculates to a 220ohm 1/4W Resistor.
    For a NB suggested Battery of Vs=3.7V, this calculates to a 35ohm 1/4W Resistor (Use a 36ohm 1/4W as next available 5% resistor size)
    QUESTION, is this Correct?
    b) Use a LuxDrive DynaOhm 20ma Variable resistor wired on the positive lead to the LED (TCSS: http://www.thecustomsabershop.com/20...stor-P847.aspx & Data Sheet: http://www.luxdrive.com/content/4006_DynaOhm.pdf).
    For the PC & CF boards, the suggested Battery is Vs=7.4V, and this would work, as the Spec Sheet states for Current Regulation 2.6V+Vf is needed, and 7.4Vs > 5.6Vf+dynaohm.
    For a NB suggested Battery of Vs=3.7V, this would not work, as 3.7Vs < 5.6Vf+dynaohm.
    QUESTION, is this Correct?

    2) For PC & CF Boards ONLY: Wiring the AV Switch LED (same as above) to the boards (for PC3.0 & CF7.0 at least, I am not sure of the pad for this is available on earlier models) using the pad dedicated to the "Power On Indicator" (NOT the Accent Pads):
    a) The ONLY option is to Calculate the resistor needed using (Vs-Vf)/If, as the Vs from the Board's Pads?
    This calculates (3.3Vs - 3.0Vf) / 20ma = 15ohm 1/8W Resistor.
    QUESTION: of page 27 of the PC3.0 manual (http://www.plecterlabs.com/Media/Doc....0-v1.0-GB.pdf) the Supply Voltage is given as 3.3V, BUT unlike the Accent Pads, no MAX MA is stated. Is there a MAX MA output on that pad? (Same question for page 35 of the CF7 manual http://www.plecterlabs.com/Media/Doc...V7-v1.0-GB.pdf).
    b) CANNOT use a LuxDrive DynaOhm 20ma Variable resistor, as for Current Regulation, 2.6V+Vf is needed, and this would not work, as 3.3Vs < 5.6Vf+dynaohm.
    QUESTION, is this Correct?

    3) For PC & CF Boards ONLY: Wiring the AV Switch LED (same as above) to the boards (for PC3.0 & CF7.0 & CF6.x at least, I am not sure of the pad for this is available on earlier models) using the one of the Accent Pads (NOT the pad dedicated to "Power On Indicator"):
    a) The Manuals for both the PC3.0 & CF7 (pages 14 & 16 respectively), suggest the "Calculate the resistor needed using (Vs-Vf)/If" method. In the manual's examples, the LED's use have a smaller "If" of 15ma, which is LESS then the MAX MA output of the pads at 18ma. SO, in that example, a resistor is required.
    QUESTION: with the Accent pad output limited to 3.3V @ 18ma, is ANY resistor required for a LED with forward specs of 3.0V and 20am? If the pad CANNOT output more then 18ma (sounds like a current regulator to me), than the LED shouldn't be able to overdraw amps, and burn itself out?

    I would appreciate feed back, as I'm still trying to learn about wiring and electronics for this hobby!

    "Thanks" in advance.

  2. #2

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    Congratulation on basically getting Ohm's Law. Makes me VERY happy to see that.

    Now to your questions, and I'll make this simple... ALL newer Plecter Lab boards (NB, PC, CF) come with a 3.3v pad which DOES give off 18mA, so if you attach your AV switch LED TO THAT, you'll be in great shape. You will only really need a dyna-ohm (or other small resistors) for reds and possibly yellow AV switches (where the Vf is at or under 3.0). You could use Ohm's law to calculate out smaller resistors, the dyna-ohm was introduced mainly for those who were terrible at math, and Ohm's Law.

    TIP: Do it the simple and easy way, and make your (and our) lives easier when it comes time to diagnose problems.

    If you decide to use the accent LED pads on a CF or PC, you will need to bridge the tiny pads anyway, so you might as well use the resistor you need or a 0 ohm if you are using blues, greens or whites.
    TCSS MODERATOR
    All n00bs READ these first (PLEASE)!!!:
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    2. FJK’s “Down and Dirty” guide to Ohm’s Law

    "Yeah, yeah, I've heard it all before... you want blindingly bright, super loud, running 1138 blinkies off of the cheapest sound card you can find AND you want all of it to run on a battery the size of a dime, and run for a very, VERY long time. That one cracks me up every time..."
    My email: fjk_tcss@yahoo.com

  3. #3

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    Quote Originally Posted by Forgetful Jedi Knight View Post
    Congratulation on basically getting Ohm's Law. Makes me VERY happy to see that.
    Thanks! I have done A LOT of research, and reading about how to wire this stuff up! I'm not going to hack something together, just to have it blow up!

    Quote Originally Posted by Forgetful Jedi Knight View Post
    ALL newer Plecter Lab boards (NB, PC, CF) come with a 3.3v pad which DOES give off 18mA, so if you attach your AV switch LED TO THAT, you'll be in great shape.
    So, with those newer boards (I have a CF7 and a NB2 on the way), IF the Forward Current > 18ma, a resistor is NOT needed (even though the Vf of the LED is < the 3.3V the pad supplies)?

    Quote Originally Posted by Forgetful Jedi Knight View Post
    You will only really need a dyna-ohm (or other small resistors) for reds and possibly yellow AV switches (where the Vf is at or under 3.0). You could use Ohm's law to calculate out smaller resistors, the dyna-ohm was introduced mainly for those who were terrible at math, and Ohm's Law.
    So, are you suggesting a DynaOhm would work off a 3.3Vs pad? 3.3V-2.6V=0.7V (if i am reading the Data sheet right, and the DynaOhm needs +2.6V the Vf of the LED to current regulate). I haven't seen a LED (5mm, 3m, etc) with a Vf less then 2.x.

    Quote Originally Posted by Forgetful Jedi Knight View Post
    TIP: Do it the simple and easy way, and make your (and our) lives easier when it comes time to diagnose problems.
    Hopefully, I will learn enough NOT to have problems that need diagnosing!! (crosses fingers)

    Quote Originally Posted by Forgetful Jedi Knight View Post
    If you decide to use the accent LED pads on a CF or PC, you will need to bridge the tiny pads anyway, so you might as well use the resistor you need or a 0 ohm if you are using blues, greens or whites.
    The Accent pads to bridge are SO TINY!! I have a CF7 wired up, with ALL I want (but those). I intend to use them, but MAN, even with a fine tipped iron, and helping hands, I am a bit tentative to try it . My sum total of soldering experience is 2 projects over 6 hours.....

  4. #4

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    Quote Originally Posted by bigkevin61 View Post
    So, with those newer boards (I have a CF7 and a NB2 on the way), IF the Forward Current > 18ma, a resistor is NOT needed (even though the Vf of the LED is < the 3.3V the pad supplies)?
    The typical Vf of a LED is an estimated average. Meaning that a Blue that has a typical Vf of say 3.1 can handle a minimum of say 2.9 and a max of say 3.3

    Quote Originally Posted by bigkevin61 View Post
    So, are you suggesting a DynaOhm would work off a 3.3Vs pad? 3.3V-2.6V=0.7V (if i am reading the Data sheet right, and the DynaOhm needs +2.6V the Vf of the LED to current regulate). I haven't seen a LED (5mm, 3m, etc) with a Vf less then 2.x.
    Many have used dyna-ohms and I've never heard of any issue. Strydur wouldn't stock items that didn't fit our specific needs. However, since you are good with Ohm's Law, you can calculate out what you need and use smaller (size wise) resistors, which should help you with internal space in your builds.

    Quote Originally Posted by bigkevin61 View Post
    The Accent pads to bridge are SO TINY!! I have a CF7 wired up, with ALL I want (but those). I intend to use them, but MAN, even with a fine tipped iron, and helping hands, I am a bit tentative to try it . My sum total of soldering experience is 2 projects over 6 hours.....
    Which is why I always advocate that new people start "small" and work their way up.
    Last edited by Forgetful Jedi Knight; 03-26-2014 at 07:20 PM.
    TCSS MODERATOR
    All n00bs READ these first (PLEASE)!!!:
    1. Forum Guidelines
    2. FJK’s “Down and Dirty” guide to Ohm’s Law

    "Yeah, yeah, I've heard it all before... you want blindingly bright, super loud, running 1138 blinkies off of the cheapest sound card you can find AND you want all of it to run on a battery the size of a dime, and run for a very, VERY long time. That one cracks me up every time..."
    My email: fjk_tcss@yahoo.com

  5. #5
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    This got me curious as I never noticed the DynaOhm spec sheet mentioned that. I grabbed a orange AV switch which is 2.1v and hooked it up with a dynaohm. At 4.7v it works as designed and regulates down to 20mA. At 3.7V it still regulates but only at 10mA. What does this mean? Not much as the LED was just as bright at both settings and just as safe.. So what I think the spec sheet is saying is that you will not get the output listed on the dynaohm unless you provide 2.6v + LED forward voltage. But it does work at lower voltages.
    Tim
    The Custom Saber Shop

  6. #6

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    Quote Originally Posted by Strydur View Post
    This got me curious as I never noticed the DynaOhm spec sheet mentioned that. I grabbed a orange AV switch which is 2.1v and hooked it up with a dynaohm. At 4.7v it works as designed and regulates down to 20mA. At 3.7V it still regulates but only at 10mA. What does this mean? Not much as the LED was just as bright at both settings and just as safe.. So what I think the spec sheet is saying is that you will not get the output listed on the dynaohm unless you provide 2.6v + LED forward voltage. But it does work at lower voltages.
    I feel honored, getting a reply from the owner! (BTW, 1) thanks for the shop! 2) so far my orders have been sent amazingly quick! 3) this is going to get addicting!)

    That makes sense! I couldn't test it like you have, as I only ordered the White AV Switch, and I have to wait a bit to get the desktop power supply, after getting a adjustable, digital soldering station (I wasn't going to try working on the CF7 with the the cheap $10, 30w iron I got to practice on my first soldering project).

    Like it has been said MANY times before on this forum, "this can be an expensive hobby", but the right equipment makes a difference!

  7. #7

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    I went back and looked at the Spec sheet out of curiosity. In order for the DynaOhm to actually do currently regulation on an LED, you have to have 2.6V+the Vf of the LED in question. If its a 2.1Vf LED and runs at 20mA, you need to supply 4.7V before it will regulate to 20mA. When using 3.7V or the 3.3V supplied by an accent pad, the Dynaohm will not regulate the current of a 2.1V LED, which is likely why you only got 10mA. I notice they make a 25 and 30mA version as well. So, if you were making a saber running on 7.4V and hooked up some blinkies out side of using an accent pad (direct from the battery), then this would work great so you would not have to think about doing any calculations for Resistors, or if you had some kind or color change LED that required multiple resistors to work right, then it would be great. I have yet to find a need for it, but I am looking. I am lucky I have an electronics store I can go to and get just about any resistor I need at the drop of a drive across town (you cant find 1.3 Ohm 1Watt resistors just anywhere). RW

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