LED momentary fire switch on DNA20

[keighles]

I posted this question in another forum, but thought I would get a faster response here. When wiring up my fire switch to the dna, Its pretty simple to follow the chart in the data sheet. but I am not sure how to hook up the LED part of it.

This is what I was thinking...I already have the 470k resistor. just not sure if I can use the leads for the switch or not...

Sorry for the crude diagram, but figured this is the easiest way to explain what i'm thinking..

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I think that the + lead for the firing switch doesn't carry enough power to light up the LED. I may have to get power straight from the battery. but the ground should work.

 

[retird]

Why not just put a led w/ resistor on the wires to the atty connector....mount the led in the mod enclosure, thus the led in the switch will not work..........I think the way you are wanting to do it requires a relay circuit where line voltage actuates a relay to turn the logic function....voltage from the battery can't work with logic switching (it will fry your DNA20D) thus the relay to isolate the logic switching from the battery voltage.....

 

[keighles]

Hmmm.... Good idea, I will have to re-think this. that is just a logic circuit.

 

[meatsneakers]

Unless that was a typo, a 470k resistor won't light at our voltages. Something closer to 220 or under.

 

[keighles]

No, not a typo...just thought that's what I was supposed to use.
Anyway I have 470ohm, 10k ohm, 10k 1/4Watt, and a 470K resistors on hand. which one would be good to use, for a nicely lit LED?

 

[MorpheusPA]

It depends on your LED. If I run the numbers for a blue or white LED at 3.7 volts, I get an answer around 40 ohms. Because the battery might be supplying 4.2 volts part of the time, I'd use a 68 ohm resistor for 15 ma power usage and a fairly bright light.

For a red LED at 4.2 volts, 150 ohms.

A 150 ohm resistor would still light a blue or white LED, just not very brightly--about 8 ma, or around 40% of the potential power the LED could handle. That would result in a dim light.

Quarter watt resistors are more than good enough for this purpose. Power dissipation in the resistor is in the 35 milliwatt range.

 

[retird]

Over the years of modding, I built several VV mods with leds....so I could tell when I'm firing.....I like the DNA20D's display function where the displayed information gets brighter when you fire the device....I no longer need a led to tell me when it is firing....

 

[bapgood]

Retird might be correct and I would check with Evolv, but the fire switch is switched to ground. So if it won't eff the DNA you could possibly run power from the battery to the led and complete the ground via the switch when pressed.

 

[retird]

I'd kinda like to look at the switch....gotta link to where you got it...or a part number...

 

[keighles]

Angel Eye Blue LED Light 3V 12mm Stainless Steel Momentary Push Button Switch No | eBay

This is the switch I'm using.

 

[retird]

Got it....see the switch....a datasheet I'll have to search for....

 

[keighles]

The only data I could find is the small amount in the description. Which doesn't tell you much.

 

[MorpheusPA]

Ditto with keighles. If it acts like others I've seen, the switch is SPST (single pole, single throw), but has the second set of connectors to light the LED. Feed 3 V to the LED and it lights when you throw the switch.

The other set of poles can carry the power for the atty, which can be any voltage you choose, VV, whatever.

 

[bapgood]

Ditto with keighles. If it acts like others I've seen, the switch is SPST (single pole, single throw), but has the second set of connectors to light the LED. Feed 3 V to the LED and it lights when you throw the switch.

The other set of poles can carry the power for the atty, which can be any voltage you choose, VV, whatever.

That would be nice if its the case, but that is not the norm in my experience. Typically the LED + and - is not switched inside the switch.

 

[keighles]

I need to hook up power to it to see if it just lights up without pushing the button.

 

[retird]

Found a schematic of a switch...not your switch, but like bap said, the led circuit is not switched inside the switch....your switch says 250V AC, light DC3V.....

 

[keighles]

Yeah, I just saw that....I don't think i will be able to use the LED. I just hooked up a D cell battery to the + and - posts and nothing.
the other two are the N/O circuit. I verified that with my ohm meter.

I like the way this switch looks, and the way it sits, it will be difficult for accidental firing.

Thanks for all the help guys.

 

[MorpheusPA]

I need to hook up power to it to see if it just lights up without pushing the button.

If you do, send 3 V in to start, and try each set of connectors. Keep in mind there's nothing except the wires resisting the current on the switch, so it's going to pull massive amps. Some basic resistor in the link wouldn't be a bad idea...

The implication that I can find--but no direct data--is that one set is for the LED and the other is the switch. There's a dual spec for the pole hookups ("AC 250V 5A;Light Voltage : DC 3V") that strongly implies that.

 

[bapgood]

Yeah, I just saw that....I don't think i will be able to use the LED. I just hooked up a D cell battery to the + and - posts and nothing.
the other two are the N/O circuit. I verified that with my ohm meter.

I like the way this switch looks, and the way it sits, it will be difficult for accidental firing.

Thanks for all the help guys.

Try 2 AAA/AA/D/etc batteries in series....or single cell lipo....you need 3 volts

It may very well work running power to the LED from the battery and running the negative to the switch. But there is two basic ways to find out....contact Evolv or try it

 

[keighles]

Ok, I tried one of my 3.7 17670 batteries...It lit up nice and bright!!!! No pressing of the button.

So I think retird plan, of wiring up the positive post to the atty postive with the resistor is the way to go. Just need to know what resistor to use.