The There Are No Stupid Questions Thread

I use short piece of 8 ga as that’s what I had handy. You don’t want it to be too long or too skinny because it’ll just add resistance. Being that thick though, does make it a little hard to bend and work with. So if I’m doing an amp draw on a smaller light where the amperage is fairly weak, I have a second wire that’s like 14 ga and a little longer that’s a lot easier to bend around and hold into place. When it comes to lower amperages a little extra resistance is no big deal.

What would the application be for this good alternative? Are you talkin about from the driver to the LED or do you mean for taking amp draws?

Thanks for your reply Jason! :+1:
I was also thinking that 8AWG would be a good “thickness”, despite the thoughness when bending it!
My use will be to check the draw in my lights, I don’t have many “hot rods” so maybe I can use a thinner (12AWG) wire? Or that would be too less?

The alternative I was referring to was using a different kind of wire, like “single core electric wire”, in copper of course. The purpose would be the same, measuring battery drain.

Wait, are you going to be measuring high amp draws or super low parasitic drain?

All of the stuff I talked about above concerns the higher amp draws. If you’re going to be measuring very low currents such as parasitic drain I would not recommend the clamp style ammeter. For that I use test leads on my DMM. The clamp style meters are great four typical amp draws but when it comes to super low amperage it just doesn’t have enough accuracy.

I don’t think single-core or any type of solid copper wire is a good choice for amp draws because you really need to get a good connection on both the battery and on the edge of the battery tube. Having the soft copper strands spread out helps to make a better electrical connection.

With the clampmeter I would be measuring higher amps, putting the wire through the “clamps”. Like my triples or quads on Turbo, not the low amps or parasitic drain :slight_smile: I wanna see how much my Convoy S6 triple with Luxeon V and a driver w/ Bistro HD OTSM is pulling from the Sony VTC6, as example.

I have a UT201E clampmeter on the way to me so I will be able to use it for that purpose.
Then I will try to order a (better) DMM to read low amps and parasitic drain.

Thanks for the complementary reply! I understand what you say, so I’ll stick to the other type of wire with soft copper strands :wink:

How can I calculate the approximate output of a light from the Amps it is pulling?
Saying: I have light with 3xLuxeon V 4000K that is pulling ~21.1A from a 18650 cell.

How can I calculate without a luxmeters/integrated spheres?

Thanks in advance!

8AWG is 2mΩ/m, kind of overkill :stuck_out_tongue: , a good bronze spring is arround 3~4 mΩ for reference.

14AWG : 8mΩ/m, a 25cm piece would be the 2mΩ which is low enough IMO.

Excellent guess. Exactly what I used to do. Figure about 70% efficiency between led tests and an actual flashlight.

Try to find a test from a known person here on the forum and the same emitter and color temp. Its not gonna be real accurate, but it gets you in the ball park.

Always use clamp meter for these amp draw tests.

If a FET driver, keep in mind the battery model plays a role in the amperage.

Thanks Robin Dobbie and JasonWW for your replies.
That seems a good way to calculate that!
These are all estimations of course, but I was wondering how much lumens it would produce.

That is a Convoy S6 I did with a FET driver from Lexel w/ Bistro HD OTSM, 3 Luxeon V installed in an led4power alluramic MCPCB, spring bypassed, copper spacer from kiriba-ru, forward clicky switch and Carclo 10511.

That thing gets HOT real quick anf puts out a small wall of light, so I was wondering how much it would be putting with that Amp draw (which will be different when using the switch and not the thick copper cable I used).

Thanks again for the replies!


At thefreeman, I went to a local store and got a relatively thick cable (4mm outter diameter), made of copper inner strands thicker than AWG inner strands.
It will work :smiley:

We don’t know what led you’re using. Different bins and color temperatures have different outputs.

So like Robin said earlier:

Maybe 4500lm if it’s CW
Maybe 3900lm if it’s WW

You might lose some amperage when you put the tailcap on and that will lower output slightly.

TIR efficiency varies, but I’d say its close to reflectors in general.

I think it was djozz? Had 4x Luxeon V in a D4 (I do, too) and measured over 5000 lumens at turn-on.
I can’t measure the current or lumens on my D4 though.

My question is, ‘Can a lighted switch be hooked up to this driver ? It will need power, I do not know where or the voltage to hook the leds too.’
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This is for the 2020 BLF O-L contest build, so any help is awesome :smiley:
You can answer here if you wish … #47CNCman's entry to the 8th annual BLF/O-L contest [ Handmade - FINISHED - ]

I do have a question about a “MTN 12mm Momentary Switch (for momentary / e.switch drivers)”
http://www.mtnelectronics.com/index.php?route=product/product&path=25_83…
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The driver i’m using to hook it to is,
http://www.mtnelectronics.com/index.php?route=product/product&path=67&pr…
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I have and understand the instructions where the 2 wires go for controlling the driver.
I have the non-led switches in hand and just ordered some with led.
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Here are the options for the driver below.

FET Driver – 20mm model FET20-SS – Zener Mod?: Yes – ~6V LVP – Firmware: Electronic Switch CU… – Turbo Timer: 120 Seconds

Electronic Switch CUSTOM Firmware Options.

1. Number of light levels: 4

2. Approximate PWM levels of each mode: (1) 10% – (2) 30% – (3) 60% – (4) – 100%

Zener Mod: Yes – ~6V LVP

This question is like asking if I can add a horn to this specific model car. It doesn’t matter the year, make or model. It can be done. You just need some DC power.

You can tap a power wire into the middle of the driver where the red led wire is soldered. That’s battery power before the main led.

It looks like your switch has an on board location for a resistor. That’s good. It should use the same ground wire as the switch circuit.

So you’ll just need to add the one extra wire and resistor. Probably a 15k to 50k resistor. All very easy.

You can see how I added a switch led wire to my L6 here. I had to add an inline resistor, though.

It will draw power whenever the tail switch is on, but I don’t think that is a problem for you.

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Thank You JasonWW :+1:
I am setting up a 2S or 6-8V configuration. Does it matter the voltage going into the switch ?
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As far as the colored leds are concerned, the resistor will drop the voltage way down to within their normal range. Without a resistor it would blow right away.
There are many different smd leds with all types of specs. Specs even change within the same model, but different color. This is why you need to experiment with resistor values. Start around 15k-30k. See what the brightness is. I think I’ve even had to go up to 100k on one of my lights due to the color and it’s high current draw.

If it were a 3 volt source I’d say start between 7k and 15k. With 6v you basically double the resistance, hence 15k to 30k.

Here is the info from MTN Electronics.
So your saying I should start with the 36K since using 2S and stack more to lower brightness ?
It comes with 2 leds installed.
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Connection Points / Bridge Points:
Because this switch was designed to be as versatile as possible, there are several different connection points and possible configurations.

Switch Connections: SW+ & SW- GND (SW- is ground).
LED Connections:
If connecting directly to Batt+ or from an MCU output: LED+ & bridge “LED- GND BRIDG.”
If switching from a negative side (such as a MOSFET): LED- & LED+. Do not bridge anything.
LED Option:

Optionally, you may have two color or white LEDs pre-installed on the switch, which are often used as indicator lights.

Three SMD 0603 resistors will come included, but not installed (4.7K, 19.1K & 36K). You can try different resistor combinations depending on your input voltage and desired LED brightness. We recommend that you start with 36K—-you can then swap or stack more resistors to increase the current from there. It is not recommended to go above a few mA of current to these small LEDs. The lower the total resistance value, the brighter the LEDs will be.

OK , I see, your L6 is a S2 configuration.
Thank You very much JasonWW :smiley:
The switches will come in Monday and I will experiment at that time :+1:
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And I’m sorry for not understanding your earlier post, Grand kids are here distracting me :person_facepalming:
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And start with the 19K resistor first. :+1:
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I’d start with the 36k.

Stacking resistors reduces resistance and makes it brighter. Higher resistance makes it dimmer.

To go above 36k you need to add another resistor in series. Sometimes you can stack them like this /\ to squeeze 2 resistors on a single pad. The proper way is to swap to a higher resistance resistor.

36k should be fine, it might be brighter than you want, but should work. If you want to dim it you can order some more resistors from ebay. I see MTNE sells a 69k resistor. If you haven’t ordered the switch yet you can have him add some of those. Otherwise, you can order an assortment on ebay. Shipping may take a while, but they are cheap. It’s handy to have an assortment on hand. You can also order an assortment of smd leds as well. It’s fun to mix and match colors.

Thank you very much Jason for explaining that so clearly for me. :smiley:
I wanted to order some in the past, but its confusing what size and resistance range to order.
Three SMD 0603 resistors will come included, but not installed (4.7K, 19.1K & 36K).
I will try again.
:+1:

If you wanted, that driver could likely be flashed with Anduril, in which case you could probably get one of pins 5/6/7 for the switch LED (likely one controls the FET and the others are unused). But that would take a bit of doing…

I was looking through the details of that driver and I noticed Richard does not recommend the zener mod in a 2s design.

“Not recommended for use with the Zener Mod option. For 2S+ cell momentary use, check out the LDO 20mm driver instead.”